What I want to discuss is a concept that I call ‘excluding the middle’ but which is more formally referred to as a logical fallacy called ‘the false dilemma‘,  the ‘either/or fallacy’ or a whole host of other things.  It’s something I see a lot in both Internetz articles and Internetz arguments.

In brief, people have a tendency to play this cute little game where a given situation can either be exactly one thing (their preference) or exactly one other thing where that other thing is some ludicrous stupid-ass extreme example that they use to attempt to prove their preference simply by how extreme (and dumb) it is.  But compared to something stupid, anything is better by comparison.

As an example, I am apparently quoted as having said that “…compared to the Standard American Diet, a diet of bug spray and skittles would be healthier.”   One extreme compared to another and the second is only better because of the awfulness of the first.  Except that I was joking…mostly.  In most arguments, the folks falling prey to this trap are not.

Now, whether or not this is just some aspect of human nature where we want things to be one thing or another, or because people are bad at making logical arguments or what I have no idea.  Nor do I really care.  It’s called a logical fallacy for a reason and I’m going to give you four explicit examples to try to get my point across.

But simply, life is not binary and most things comes in varying degrees of extreme and shades of gray.  As my favorite author once put it “The universe can count beyond two.”  He was using this statement in a different context (to point out that most things fall into a yes/no/maybe type of situation and there are rarely simply yes/no answers) but it applies here too.  Hopefully this little piece will help you count beyond two.

.

The HIT Example

For those who live under a rock, HIT refers to High Intensity Training (not to the confusingly similarly named HIIT or High-Intensity Interval Training).  Developed by Arthur Jones (as much to market Nautilus equipment or anything else) but truly popularized by Mike Mentzer (who called it Heavy Duty training), HIT has more or less become synonymous with doing 1 set to failure of a given exercise (interestingly, Jone’s original HIT was not like this at all and was actually a fairly moderate volume of training).  Yes, there’s more to it. No, I’m not going into details here because it doesn’t matter.

But in arguments with HIT’ers, if you suggest doing more than one set, you typically see a great example of what I’m talking about.  Specifically, you will often see the statement to the effect of “If you’re going to do more than 1 set, why not do 10, or 20, or 80?”  HIT’ers see the world in two simple binary situations: either you stop at one set or you do as many sets as possible.

That is, they don’t seem to have considered that one could do say, 4-8 sets of an exercise.  That the options are just 1 and ‘all’.  And since 1 set is better than ‘all’ sets, clearly it’s the correct choice.

They are excluding the middle: It’s not as if you can’t do a moderate number of sets (say 4-8 or whatever number might be optimal) and the only options are 1 or ‘all of them’.

.

The Clean Eater Example

The idea of eating ‘clean’ is one that runs rampant in the physique sports.  Simply stated, ‘eating clean’ means eating only unprocessed foods in the diet.  Well, except when it’s inconvenient, it’s always amusing watching rabid clean freaks rationalize foods that don’t fit their definition (Crystal Light comes to mind) while eliminating foods (such as dairy) which clearly do fit their definition.  And when you get into arguments with clean freaks and suggest that it’s not required to eat clean 100% of the time, you will often get a response to the effect of “I guess I could go binge on junk food and McDonald’s and pizza at every meal, sure.”

I’d note that clean freaks often include a ‘cheat day’ where they go out of their way to eat the most junk humanly possible, often to the point of making themselves sick.  As well, many fall into the trap whereby if even a gram of an ‘unclean’ food passes their lips, they have ruined their diet and must go binge on everything they can get their hands on.  They need to read A Guide to Flexible Dieting.

In the clean freak’s mind, there are two binary options: you either eat clean 100% or you’re eating nothing but junk food at every meal every day.  The idea that you might ‘eat clean’ (whatever those words mean to you) 80-90% of the time and include selective ‘unclean foods’ (whatever that means to you) the other 10-20% of the time is simply an inconceivable one to many.

They are excluding the middle: it’s clean 100% of the time (except when it’s not) or junk food 100% of the time, you can’t do anything in the middle.  Even though you clearly can.  And most do, and more probably should.

.

The Paleo Diet Example

Arguing with rabid paleo folks is about the same as arguing with the clean eating crowd.  I can recall specific arguments where the suggestion that grains (which represent unholy evil to the paleo crew) can be part of an overall diet was met with the counter-argument of “I’d never eat a diet that is 80% carbs.” Or something to that effect.

That is, the paleo eater seems to see the world as one of two things: you are either a strict paleo eater consuming nothing but meats, veggies, fruits and other paleo-approved ™ foods (and I’d note here that the paleo folks are about as flexible with their definitions as the clean eaters, routinely rationalizing foods that they want to eat while ignoring others based on whim) or you’re living on nothing but refined grains.

It’s one or the other, if you’re not 100% paleo, you’re 100% at the other extreme.   Apparently that whole concept of an athletic diet where you eat lots of protein, fruits, vegetables AND some amount of grains is simply inconceivable.  Despite the fact that athletes and bodybuilders have done that for decades.

They are excluding the middle: your diet is either 100% paleo (except for the exceptions they justify) or you’re eating 80% refined grains.  There is no possible middle ground that they can conceptualize.

.

The HIIT/LSD Example

Now I am talking about High-Intensity Interval Training along with the whole silly either-or argument that is going on in the world of conditioning and cardiovascular training (something I’ve written about at length in the Steady State vs. Interval Training series).   Basically, and this is mostly a marketing thing/a backlash to the over-emphasize on low-intensity cardio of previous years, folks have flip flopped and it’s all intervals all the time.

Coaches will argue to the effect of “I would never have an athlete do low intensity work, marathon runners have a poor power output” or something roughly to the effect.   You’ll see similar stupidity aimed at folks aiming to lose fat where the statement is something akin to “Hours of low intensity work burn off muscle.”  As if the only way to do aerobic work is by doing hours and hours of it every day.

Apparently 45-60 minutes of low intensity work can’t be done even if dieters and contest bodybuilders have done exactly that for about 30 years.  Nor can a mix of low intensity work (i.e. 2-3 sessions per week or more) plus some interval work (1-2 session).    Or some other mixture depending on your goals and needs.  You know, like just about every endurance athlete in the world.

They are excluding the middle: It’s either nothing but interval sessions at every workout OR you’re training for the Tour De France and doing 30 hours per week of aerobic work, you can’t do anything in the middle.

.

Summing Up

Stop excluding the middle.

1. Macronutrients: nutrients consumed in large amounts (‘macro’ = large)
2. Micronutrients: nutrients consumed in small mounts (‘micro’ = small)

So macronutrient refers to protein, carbohydrates, fats and alcohol, those nutrients that, when they are consumed are generally consumed in gram or larger amounts.  The micronutrients refers to vitamins and minerals which are usually consumed in very small amounts (e.g. the DRI for Vitamin C is 60mg where 1mg is 1/1000th of a gram).  I’m not going to talk about micronutrients in this article and will only focus on the macronutrients, specifically protein, carbohydrate, fat and alcohol.

I’m also going to assume that you’re getting your nutrients through food and it’s going in through your mouth. Certainly nutrients can be given via infusion but this is usually done in a hospital setting (sometimes athletes will rehydrate and carb-load with IV fluids and glucose, mind you) and I’ll assume you’re not doing that.

.

Digestive Efficiency and Your Poop

Clearly anything you eat has to go through the process of chewing, swallowing and into the stomach for digestion.  There a bunch of stuff happens where the nutrients are broken down to one degree or another.  And either they get absorbed (moving into special cells to be released into the bloodstream, or lymphatic system in the case of dietary fats) or not.  If you’re particularly interested in the digestion processes of the different macronutrients, I’d refer you to the specific articles:

A Primer on Dietary Fats Part 1 for fat digestion.
A Primer on Dietary Carbohydrates Part 1 for carb digestion.
What are Good Sources of Protein-Digestibility for protein digestion.

Nutrients that aren’t absorbed in the stomach move further down the intestine where in some cases (for example, certain fibers), they are digested by special bacteria and re-enter the bloodstream as short-chain fatty acids.  This is discussed in Fiber – It’s Nature’s Broom.

Nutrients that pass that stage eventually come out the other end in your poo and we needn’t talk about that much more. I’ll only note in this regards that digestive efficiency in humans is generally very high.  Fats are absorbed with about 97% efficiency (e.g. if you eat 100 grams fat, you’ll absorb 97 grams of them), animal source proteins are about 90-95%, vegetable source proteins can be in the 80% range and carbohydrates vary drastically depending on their form, fiber content, etc.  But for the most part, with the exception of high-fiber foods, you’re not losing a lot of calories in your poop.

I would note, having said more about poop than necessary at this point, that there appears to be slight differences (based on the gut bacteria present) in how efficiently individuals absorb calories from the diet but this only amounts to perhaps a 100 cal/day difference between the highest and lowest people.  OF course, in cases of specific disease where there is nutrient malabsorption, all these comments go out the window but I won’t talk about that here.  I’ll assume you have a normally functioning gut, etc.

.

Fates of Ingested Nutrients: Oxidation or Storage

So what happens after nutrients get through the stomach and intestines and into the body?  Broadly speaking, there are two primary fates for nutrients at this point which are oxidation or storage.  A third that I should at least mention is that, under certain conditions, nutrients will sort of ‘sit’ in the bloodstream either causing problems there or eventually being excreted in the urine.  Outside of various pathophysiologies (e.g. runaway diabetes where glucose is lost in the urine in large amounts), the urine excretion route is generally minimal approaching insignificant and I won’t focus on it further here.

Oxidation simply refers to the direct burning of fuels for energy.  This can occur in the liver, skeletal muscle and a few others places and all 4 macronutrients can strictly speaking undergo oxidation after ingestion.  So fatty acids from dietary fat ingestion can be used to produce energy, carbohydrate can be burned off, a little appreciated fact is that under normal circumstances as much as half of all dietary protein ingested gets metabolized in the liver via a process called deamination with some of it simply being burned off for energy.

Storage should be fairly clear and the nutrients (with the exception of alcohol) can be ‘stored’ in the body for later use.  Carbohydrates can be stored as liver or muscle glycogen, under rare circumstances they are converted to and stored as fat.  Dietary fat is stored either in fat cells or can be stored within muscle as intra-muscular triglyceride (IMTG).  Under certain pathological conditions, fat gets stored in places it’s not supposed to go, a situation called ectopic fat storage.  In a very real sense there’s no true store of dietary protein although amino acids from protein digestion are used to make various proteins and hormones in the body. Skeletal muscle is, in essence, a ‘store’ of protein in the body.  There is no store of alcohol in the body.

Which is the segue into the only real point I have to make in this piece: as it turns out, the size of a nutrient’s store in the body is inversely related to the body’s propensity to oxidize it after ingestion.  This is especially true in terms of the size of the store relative to the amount consumed on a daily basis.

Put a little more clearly, the better the body’s ability to store a given nutrient, the less it tends to alter/increase oxidize that nutrient after ingestion.  And vice versa, the smaller the store in the body of a given nutrient relative to intake levels, the more likely the body is to oxidize that nutrient after ingestion.  I’ve shown the implications of this in the table below and will make comments about specific nutrients below that.

.

.

Fat
Body fat stores are effectively unlimited as individuals reaching 1000 lbs (and 70-80% body fat) have demonstrated.  Even a relatively lean male at 180 lbs and 12% body fat is carrying 21 pounds of fat.  Each pound contains maybe 400 grams of actual stored fat and that means about 8500 grams of fat stored in the body.  Contrast this to a relatively high daily intake of perhaps 100-150 grams per day and you can see that the body’s store of fat is much much higher than what you eat on a day.  And most people aren’t 12% body fat.

But for the most part, ingested dietary fat has little impact on fat burning in the body; that is, when you eat dietary fat, your body doesn’t increase fat oxidation.  One exception is if an absolutely massive amount of fat (like 80 g) is consumed all at once but even then the effect is fairly mild.  Some specific fats, notably medium chain triglycerides, are somewhat of an exception to this; they are oxidized in the liver directly.  Rather, the primary controller of dietary fat oxidation in the body is how many carbohydrates you’re eating, which I’ll explain momentarily.

Carbohydrate
For carbohydrate, the body’s stores are relatively close to the daily intake.  A normal non-carb loaded person may store 300-400 grams of muscle glycogen, another 50 or so of liver glyogen and 10 or so in the bloodstream as free glucose.  So let’s say 350-450 grams of carbohydrate as a rough average.  On a relatively normal diet of 2700 calories, if a person eats the ‘recommended’ 60% carbs, that’s 400 grams.  So about the amount that’s stored in the body already.

For this reason, the body is extremely good at modulating carbohydrate oxidation to carbohydrate intake.  Eat more carbs and you burn more carbs (you also store more glycogen); eat less carbs and you burn less carbs (and glycogen levels drop).  This occurs for a variety of reasons including changing insulin levels (fructose, for example, since it doesn’t raise insulin, doesn’t increase carbohydrate oxidation) and simple substrate availability.  And, as it turns out, fat oxidation is basically inversely related to carbohydrate oxidation.

So when you eat more carbs, you burn more carbs and burn less fat; eat less carbs and you burn less carbs and burn more fat.  And don’t jump to the immediate conclusion that lowcarb diets are therefore superior for fat loss because lowcarb diets are also higher in fat intake (generally speaking).  You’re burning more fat, but you’re also eating more.  But that’s a topic that I’ve not only addressed previously on the site but may look at in more detail in a future article with this piece as background.

Protein
The body’s total protein stores (and note again that this isn’t a true store in the sense of body fat and glycogen) is maybe 10-15kg or so when you add it all up.  Which is pretty high compared to an average daily intake.  The DRI for protein is only about 50-60 grams per day for the average person and even folks eating 200-300 grams per day are still eating far less protein than stored.   Which is why protein oxidation rates can change with intake.

As I mentioned above, an under-appreciated fact is that about half of all ingested dietary protein is metabolized in the liver (details on this can be found in The Protein Book).  Some of it is oxidized for energy while others are converted into other things (including glucose and ketones) for use elsewhere.  But, protein oxidation rates do change in response to intake.  So, when protein intake goes up, oxidation will increase; when protein intake goes down, oxidation rates decrease.  This change isn’t immediate (as it more or less is for carbohydrates) and takes 3-9 days to occur but mis-understanding of this process has led to some goofy ideas such as protein cycling.

But it also explains one other issue of importance to protein which has to do with speed of digestion. Early studies, including the oft-cited study on whey and casein by Boirie find that fast proteins are burned off for energy to a greater degree than slower digesting proteins.  Since the body doesn’t have anywhere to store the rapidly incoming amino acids, it simply burns off more for energy.  This, along with differences in handling (e.g. the fact that fast proteins are absorbed by the gut as discussed in Casein Hydrolysate and Anabolic Hormones and Growth – Research Review) are a big part of why slower digesting proteins invariably lead to better overall protein retention in the body; not only does more make it into the bloodstream but less is burned for fuel.

Alcohol
And, finally, as noted above, there is absolutely no store of alcohol in the body.  None whatsoever.  Effectively, alcohol is seen as a sort of metabolic ‘toxin’ or ‘poison’ to the body.  And this means that alcohol oxidation is 100% perfect, that is, the body will effectively do everything in its power to get rid of the alcohol increasing alcohol oxidation to maximum (which means decreasing the oxidation of other nutrients consumed with that alcohol) so that the alcohol can be gotten rid of.

I’m going to ask readers not to read anything into the above paragraph, don’t infer or try to draw conclusions about how alcohol might or mightn’t fit into the diet in terms of anything.  As it turns out, alcohol is an oddity among nutrients with seemingly contradictory effects on things.  I’m going to address that in detail in a forthcoming article and, for now, just take the above as some much needed background information.

.

Summing Up

And that’s that.  After consumption and digestion, nutrients have a couple of primary fates in the body which are oxidation (burning) and storage (for use later).  And, as it turns out, the propensity for the body to store or oxidize a given nutrient is related to the body’s built-in store relative to intake.  In the case of dietary fat, where stored fat is much higher than daily intake, the body tends to store incoming fat and burn very little.  Fat intake per se has very little impact on fat oxidation rates.

Rather, the rate of fat oxidation is related to carbohydrate intake as the body is able to precisely alter carbohdyrate oxidation to changing intake.  Eat more carbs and burn more carbs (and less fat); eat less carbs and burn less carbs (and more fat).  Protein is somewhere in the middle, oxidation can increase or decrease relative to intake but the effect takes time (3-9 days).   Finally is alcohol, with no storehouse in the body, alcohol oxidation will take 100% precedence over everything else when it is consumed.   I’ll discuss the implications of this in an article on alcohol (and it’s rather schizoid effects on body weight and body composition in a later article).

.Fat and Cholesterol

Although I recently examined Fat and Cholesterol in some detail in A Primer on Dietary Fats Part 1 and A Primer on Dietary Fats Part 2 back in May, I want to take a briefer, more streamlined look at them in today’s article.  Readers wanting more details can click the above links.

Even though they are chemically and nutritionally distinct substances, dietary fat and cholesterol are so linked in the minds of most people that I’m going to discuss them together.   As well, along with the never-ending debate over carbohydrates in the diet, the issue of dietary fats is one of almost constant debate in both nutritional sciences and among nutritional experts.   I’m not going to get into those debates in any real detail here (since it’s about the basics) but interested readers can read Carbohydrate and Fat Controversies Part 1 and Carbohydrate and Fat Controversies Part 2 if they want more details.

First let met get cholesterol out of the way since I don’t actually have a tremendous amount to say about it. Cholesterol plays a number of roles in the body not the least of which is involvement in the structure of cell membranes in the body.  As well, cholesterol provides the ‘base’ for the steroid hormones, testosterone, estrogen, progesterone and others are synthesized out of cholesterol in the body.

Of course, when most people hear the word ‘cholesterol’, they immediately think heart disease and, certainly, one aspect of cholesterol metabolism in the body is that it can cause atherosclerotic plaques (essentially the cholesterol builds up in arteries, potentially blocking blood flow).

Please note: I am vastly simplifying a much more complicated topic.

And this tends to be the source of much confusion, especially among the lay public, about diet; they confuse dietary cholesterol intake with blood cholesterol (aka blood lipid) levels.  I’d note, and again this is more complicated than I want to cover here, that blood cholesterol levels are only one of several contributors to the issue of heart disease.  Others contribute.

But there tends to be an idea that dietary cholesterol intake is a primary determinant of blood cholesterol levels when, simply, this isn’t generally the case.  Certainly a percentage of people seem to be sensitive to dietary cholesterol intake (in terms of how their blood cholesterol responds) but, in the majority, dietary cholesterol intake per se has very little impact on blood lipid levels.

As well, your body generally makes more cholesterol (in the liver) than you eat in a day; that’s unless dietary cholesterol intake is exceedingly high.   Additionally, the live modifies how much cholesterol it produces depending on daily intake.  If dietary cholesterol intake goes up, the liver makes less; if dietary cholesterol intake goes down, the liver makes more.  The body is smart that way.

Rather, the types and amounts of dietary fat being consumed play a far larger role in blood lipid levels.  Frankly, I don’t have much more to say about dietary cholesterol, it’s simply not that big of a deal unless you are in that small percentage of folks who are sensitive to it.  Rather, I want to talk a bit more about dietary fats.

Of course, a primary role of dietary fats in the body is to be used for energy and it was assumed for many years that this was the only real role of fat, to provide energy storage.  This was especially true of stored body fat which was thought for decades to provide only a passive storage depot of energy; rather it turns out that fat cells do much more in the body, producing hormones and such that affect myriad processes elsewhere in the body (a topic I’ve discussed at length on the site and in my books)..

Fats are also found in the cell membranes of various tissues (and the type of fat stored there can affect various cellular processes).  As well, fats can be used to make eicosanoids, chemical messengers made from specific fatty acids that affect numerous biological processes.  Specific dietary fats can also affect gene expression in certain cells, impacting on things like fat storage and oxidation and many others.

From an energetic standpoint, fats are typically assigned a caloric value of 9 kilocalories/gram (~38 kj/g); there are slight differences between specific fatty acids however.  As well, there is some evidence that different fats have a slightly different propensity to be stored vs. burned after consumption although the differences between the fatty acids are relatively small.  I’d mention for completeness that dietary cholesterol has no energetic value to the body.

The biggest controversies regarding dietary fat usually revolve around the health effects of its consumption. It’s not unfair to say that, for many years now, dietary fat has been the whipping boy of the nutritional world (though carbohydrates are taking that role in recent years): fat makes you fat, fat causes heart disease and cancer, fat is probably responsible for terrorism in the US and the decline in the family unit. You name it and the problem has probably been blamed on dietary fat by certain groups.  At the other extreme are folks who argue that dietary fats have no health negatives, that they can be consumed effectively without limit or concern.

As with so many extremist stances, the truth is a little different and tends to lie somewhere in the middle.

In the past ten years or so, the issue of fat quality (i.e. type of fat) has become just as important as that of fat quantity (i.e. amount of fat). Simply put: all fats are not the same in terms of their effects on health.  As well, whether a specific fat is good, bad or neutral in terms of health depends to a great degree on the context in which it’s eaten; this is a concept that neither extremist group can seem to wrap their heads around.

Whether the person is active or inactive, fat or lean, the rest of their diet, gaining or losing weight, and a host of others all contribute to the effect a given fat will have on the body.  I’m not going to go into further details here, I’d suggest you read Carbohydrate and Fat Controversies Part 1 and Carbohydrate and Fat Controversies Part 2 for more details.

In any case, dietary fats are generally divided into four distinct categories, I’m going to look at each in brief next.

Trans-Fats

Trans-fatty acids are a man-made fat made by bubbling hydrogen through vegetable oil to make it semisolid with a longer shelf-life; I’d note that there are naturally occurring trans-fatty acids found in foods as well.  Margarine is probably the example most readers are familiar with although trans-fatty acids (also called partially hydrogenated vegetable oils) are commonly found in most processed foods (there is currently a big push for trans-fat free foods to be produced commercially).

Of the four types of fats, trans-fatty acids have the least amount of debate around them; their intake at even low levels tends to have exceedingly detrimental impacts on things like blood lipid levels and diabetes risk.  Due to the high reliance on processed foods in the modern diet, trans-fatty acid intake is thought to be at least one part of the problems being seen in the modern world (note: there are certainly other contributors).

Saturated Fats

Saturated fats are found almost exclusively in animal products (two exceptions are coconut and palm kernel oil) and are solid at room temperature.  Traditionally, the impact of saturated fats on blood lipid levels and heart disease risk has been thought to be universally negative but it turns out to be much more complicated than this.  While some saturated fats do reliably raise blood cholesterol levels (primarily due to an impact on liver metabolism), others are completely neutral.   Anybody interested in this topic may wish to read the journal article Saturated Fats: What Dietary Intake.

As well, as I mentioned above there is far more to heart disease risk than just blood cholesterol levels.  And, as also noted above, the overall impact of any fat (including saturated fats) on health risk depends on the context of their intake.  In one context (e.g. low fruit/vegetable/anti-oxidant intake, high stress, inactivity, high body fat, excessive total energy intake), a high saturated fat intake may be exceedigly harmful.  In a different context (e.g. high fruit/vegetable intake, low stress, high activity, low body fat, appropriate energy intake), they may have no effect.  I hope that any of the pro-saturated fat folks reading this article will read this paragraph a couple of times before they leave me comments about how I’m anti-saturated fats.

I’d finish by noting that saturated fats are not an essential nutrient.  They aren’t required for life and, even if they were, the body can produce them from other sources.

Monounsaturated Fats

Monounsaturates are present in almost all foods which contain fat and are liquid at room temperature (quite in fact, the majority of fat in most ‘high-fat’ foods is monounsaturated).  Olive oil is arguably the most well-known of the monounsaturated fats and has received a great deal of attention as a relatively healthy fat. Monounsaturates have a neutral, if not beneficial, effect on health and it’s thought that the high olive oil consumption among Mediterraneans is partly responsible for their robust health (there are ceertainly other factors involved here).

Like saturated fats, monounsaturated fats are not an essential nutrients, they may confer health benefits but they are not required for survival.

Polyunsaturated Fats

Polyunsaturated fats are found primarily in vegetable oils and are liquid at room temperature. They are generally claimed to have a positive effect on human health although, as always, things are a little more complicated than that.  Polyunsaturated fats come in two major “flavors”, referred to generally as omega-three and omega-6 fatty acids.

The omega-3 fatty acids include a number of different fatty acids including the ‘parent’ fatty acid alpha-linoleic acid (ALA) found in things such as flax oil along with the fish oils (EPA and DHA).  I would be surprised if anybody reading this hadn’t heard of the fish oils or their benefits.  In sum, fish oils do just about everything, they decrease inflammation, help with depression (especially while dieting), decrease enzymes involved in fat storage and increase the levels of enzymes involved in fat burning.   I’d finish by noting that the conversion of ALA to EPA is fairly low and the further conversion of EPA to DHA is basically insignificant.  For this reason, taking preformed fish oils is generally required to impact body levels of EPA/DHA to any great degree.

Similarly, the omega-6 fatty acids include a host of different fatty acids including linolenic acid (LA), found in many vegeteable oils, along with things such as arichnidonic acid (AA) which are made from metabolism or LA within the body.

I’d note that both the w-3 and w-6 fatty acids are part of a more general class of fats called essential fatty acids, that is they are essential nutrients; that is, as explained in A Primer on Nutrition Part 1, they are required for life and cannot be made within the body.  In the modern diet, it’s generally pretty easy to get w-6 fatty acids through the diet, unless folks consume fatty fish, w-3 are much harder to come by (hence the general need for some type of supplementation).

Now, there is some controversy over w-3 and w-6 intake with excessive w-6 intake being thought to cause some health problems (such as inflammation).  In the modern diet, the intake of w-6 fatty acids to w-3 is about 20-25:1 or so and it’s been thought that a ratio closer to 1:1 or 4:1 would be healthier with the excessive w-6 intake causes problems.  Some groups have even blamed current health problems less on saturated fat intake and more on a high w-6 intake due to the use of vegetable oils in the modern diet.

However, as I discussed in more detail in A Primer on Dietary Fats Part 2, current research calls this into question with mortality rate generally decreasing with increasing w-6 intake and some research suggesting no real impact on inflammation of ‘excessive’ w-6 intake.  I’m not going to go into any real detail here, please read that article for more information.

Dietary Fats: Summing Up

I expect the issue of dietary fats to remain an area of controversy for some time to come.  New functions of dietary fats are still being found and the impact of dietary fats on overall health (not simply limited to heart disease) will continue to be examined.  As I noted above, I feel that the impact of a given type of dietary fat on health is entirely context dependent, an issue that the individuals involved in both sides of the debate seem to have missed.  Since I’ve discussed this in detail in other articles linked in this piece along with touching on it briefly above, I won’t discuss it further.

Everything else: Fiber, Alcohol, Vitamins and Minerals

I recently looked in some detail at fiber in Fiber – It’s Nature’s Broom and only want to touch on it in brief here.  While not an essential nutrient (e.g. you won’t die if you don’t eat it), fiber does play a number of important roles in human health in nutrition.  If nothing else, high-fiber intakes tend to keep people full and, generally, high-fiber diets are associated with greater weight loss or at least less weight gain.  There are other effects as well, see the above article for the details.

Fiber can be subdivided into a variety of different categories but, practically speaking, the main ones of importance are soluble and insoluble fiber. Soluble fibers mix in water and take up a lot of space in the stomach, it also holds food in the stomach longer: this tends to increase feelings of fullness.  In contrast insoluble fibers don’t mix with water but help with bowel regularity and keep the colon healthy.

Both types of fiber appear to be important to human health and both are found in varying degrees in foods such as fruits and vegetables (grains have varying amounts of fiber depending on how processed they are).

Alcohol isn’t really a nutrient in that it provides nothing of actual nutritional value except for calories.  Even there, alcohol intake doesn’t seem to scale with predicted weight gain although nobody is quite sure why this is the case.  Some studies suggest that some alcohol calories go ‘missing’ but nobody can figure out where they are.  Alcohol also tends to impact on metabolism in a way that can promote fat gain.  Certainly alcohol can have a place in any diet (with a large body of research suggesting that moderate alcohol intake has health benefits depending on the specifics) but excessive amounts can cause varying problems.

Finally there are vitamins and minerals which serve innumerable roles in the body and which include a host of essential nutrients (again, can’t be made in the body, required for life).  Minerals such as calcium are structural (e.g. bone) along with being involved in cellular signalling.  Iron is involved, of course, in the formation of red blood cells, important for overall health and performance.  Zinc is involved in immune system function and a host of other processes (including appetite regulation).  Vitamins act as nutritional co-factors and are necessary for the body to function optimally.

Vitamins and minerals are found to some degree in all foods with amounts and types depending on the specific food.  Fruits and vegetables tend to be nutritional powerhouses in this regards but some vitamins and minerals are optimally consumed in foods of animal origin (for example, the iron in red meat is absorbed roughly ten times better than the iron in vegetable source foods and B12 can only be found ‘naturally’ in animal source foods).

In that context, I’d note that a class of nutrients called phytochemicals are only found in plant foods and there is currently a great deal of interest in the health benefits of these compounds.  They aren’t essential by any stretch but may confer health benefits.   Various anti-oxidant nutrients are also found in varying amounts in these foods and, while anti-oxidant supplementation has generally shown little to no real health benefits, diets high in food-based anti-oxidants have been found to confer many health benefits.

To keep the piece manageable, I’m going to divide it into two parts with Part 2 being run on Thursday.  Today I want to look at the issue of essential vs. non-essential nutrients as well as protein and carbohydrates.  On Thursday, I’ll tackle the issue of dietary fats along with everything else (fiber, alcohol, vitamins and minerals).

Essential vs. Non-essential Nutrients

The body has a requirement for somewhere around 60 nutrients on a daily basis for normal functioning.  Please note: as nutritional science has progressed, it’s now become apparent that many, many more nutrients may contribute to optimal health, although they are not necessarily required for survival.  Put differently, you can live without consuming them but you might be healthier or perform better if you did eat them.

I should also mention that this list of 60 nutrients includes things such as air and water that, while they aren’t considered as nutrients per se, are usually not an issue.  Put differently, if you’re having issues obtaining adequate amounts of air or water, you have bigger problems to deal with.

Of more relevance to today’s article, nutritional science often groups nutrients into the categories of essential and nonessential (recently the terms indispensable and dispensable have come into vogue) which is what I’d like to discuss next. For quick summary, there are roughly 8 essential amino acids, 2 essential fatty acids, a host of vitamins and minerals and a few others substances that are required on a daily basis.  You might note that carbohydrates were not listed as an essential nutrient, a topic I’ll come back to below.

So what is an essential nutrient as opposed to a non-essential nutrient?  I’m actually going to answer that by explaining what a non-essential nutrient is first.  Contrary to what it sounds like, the term non-essential (or dispensable) doesn’t mean that the nutrient isn’t essential for life; rather, it’s not essential that the nutrient be obtained from the diet itself.

Translating that into English, there are some nutrients (such as glucose, certain fatty acids and just over half of the amino acids) that can be made in the body from other sources.  For example, many amino acids can be made in the body via metabolism from other amino acids; as well, glucose can be made in the body from a number of different substances.    So while these nutrients are essential for life and survival, it is not essential that they be obtained from the diet.

At the same time, there are nutrients that cannot be made by the body (the vitamins and minerals are examples, so are the essential fatty acids and roughly the other half of the amino acids) and are hence considered essential nutrients. That is, it is essential that they be obtained from the diet (generally on a daily basis).

In short, to be considered essential, a nutrient must meet two primary criteria:

1. That nutrient is required for survival
2. That nutrient cannot be made in sufficient quantities (or at all) by the body

So if a nutrient isn’t required to keep you alive, it’s not essential (even if consuming it improves health or what have you).  If it’s required for life but the body can make sufficient amounts of it, it’s still not essential to get it from the diet; hence it is not an essential nutrient.  Only when a given nutrient is both required for survival and can’t be made in the body in sufficient amounts is it an essential nutrient in terms of what I’m talking about here.

Although I want to keep this piece focused on the basics, I should probably mention one odd exception which is Vitamin D (currently getting a lot of press, and for good reason, in various places).  Vitamins and minerals, generally, can’t be made in the body and must come from the diet.  But while Vitamin D can be obtained from the diet (many foods are fortified with it), and is an essential nutrient, it is actually made by the body in response to sunlight hitting the skin.

I want to make it clear that the above is a bit of a simplification and the topic of essential and non-essential nutrients can be made considerably more complicated.  For example, some nutrients can be considered conditionally essential.  That is, under normal conditions, the body may make plenty of a given nutrient (meaning that it is not required that the nutrient come from the diet) but under other conditions the body needs more than it can make.   Under those conditions (usually involving things like disease and severe trauma), a nutrient that is normally non-essential becomes essential (must be obtained from the diet).  Hence conditionally essential.

.

Protein

The word protein come from a Greek word meaning “the first” which is meant to signify its primary role in human nutrition.  While you can survive rather extended periods without carbohydrate or fats in the diet, a long-term lack of protein intake leads to a loss of body tissue (muscle and organ protein), function and eventually death.

Whole dietary proteins are made up of smaller units called amino acids of which ~20 occur in the diet (there are many more that occur in the body).  Of those 20 or so amino acids, roughly eight are considered essential meaning that they must come from the diet on a daily basis.  Under certain conditions, such as stress and trauma, some amino acids also become conditionally essential; glutamine is perhaps the most commonly cited example with much higher amounts that can be made in the body being required under those kinds of conditions.  There are other examples but few would be relevant outside of some very very specific situations (usually involving severe malnutrition or disease).

A primary distinction between protein and carbohydrate/fat is that only protein contains dietary nitrogen (which is technically an essential nutrient).  Since humans can’t ‘fix’ nitrogen from the air like plants, we have to obtain it from the diet.  And that nitrogen is found in the individual amino acids that make up whole food proteins.   Also, while there can be some interconversion of protein (more accurately, amino acids) to carbs or fat (this last one is very rare), neither carbs nor fat can be made into amino acids.

Proteins/amino acids have a number of crucial roles in the human body but most of them are structural (meaning the protein is used to build things).  Many hormones are made of protein (some examples are IGF-1 and Growth Hormone), your organs, muscles, skin and hair all contain protein; protein has numerous other roles in the body as well.  Protein can also be used to produce energy in the body, usually by conversion to other nutrients (almost always glucose).  For example, during long-term aerobic exercise, the breakdown of amino acids (specifically leucine) can provide 5-10% of the total energy generated.

Something to note is that, in contrast to carbohydrate (which is stored in both muscle and liver) and fat (which is stored on your butt and stomach), there is no real storage form of protein unless you count the relatively small amount floating around in the bloodstream and the protein that makes up your muscles and organs.  But this isn’t a true storage form like for carbohydrates and fats since, in general, breaking down body protein is a bad thing (as I mentioned above).

In the diet, protein is found to some degree in almost all foods with the exception of pure fats like vegetable oils and such and some totally refined carbohydrates such as candy (e.g. jelly beans). Fruits and vegetables contain fairly small amounts of protein (perhaps a gram or two per serving) while beans and nuts can contain significant amounts of protein. But most people in modern society get their protein from animal based products: meat (red meat,  chicken, fish), milk, cheeses, etc.

In terms of caloric content, protein has traditionally been assigned a value of 4 kilocalories/gram (~16.8 kj/g) but this is currently a topic of some debate.  Because of how it is digested and assimilated in the body, at least one researcher is suggesting strongly that protein be given a lower caloric value (roughly 3.2 kcal/g or 13 kj/g) than the traditional value.

I covered a great deal of detail regarding different dietary proteins on the site in What’s Are Good Sources of Protein; of course The Protein Book also discusses this topic in detail.

Carbohydrate

The term carbohydrate refers to a number of different organic compounds ranging from simple sugars (e.g. glucose and fructose) to disaccharides (e.g. sucrose, lactose) all the way up to starches (long chains of individual carbohydrate molecules bound together).   Because of it’s chemical structure, you will often see carbohydrate abbreviated as CHO (for carbon, hydrogen, oxygen).

In the body, carbohydrate’s role is primarily energetic, that is it provides energy (through breakdown) in various tissues of the body.  Most tissues in the body can use glucose for fuel and, quite in fact, most will use glucose if it is available (they will switch to using fats or ketones if glucose is not available in sufficient amounts).  A few tissues of the body can only use glucose for fuel.

And while the above might suggest that dietary carbohydrates are essential, this isn’t the case.  Recall from the discussion above that, to be considered essential a nutrient must not only be required by the body but cannot be made in sufficient quantities.  And, as I’ve also discussed elsewhere, the body is able to produce some carbohydrate from the breakdown of other nutrients, specifically about half of the amino acids, glycerol (the backbone of both dietary and body fat) and lactate.

In general this process (called gluconeogenesis which simply means the production of new glucose)  is able to cover the body’s basic daily needs.  As well, with low-carbohydrate diets, there is a whole body shift in fuel use from carbs to fats and ketones which reduces carbohydrate requirements.  This is discussed to some degree in nearly all of my books but the greatest detail can be found in The Ketogenic Diet.

I would finish by noting that high-intensity exercise tends to increase carbohydrate requirements beyond what the body can make putting carbohydrates into the conditionally essential category I discussed above (e.g. the body needs more than it can produce itself).  For those individuals who wish to perform high-intensity activity such as intensive weight training or even high intensity metabolic work, some amount of carbohydrates generally becomes required in the diet.  The issue of daily carbohdyrate requirements is discussed in much more detail in How Many Carbohydrates Do You Need?

Carbohydrates can be stored within the body in the liver or muscle as glycogen (a long chain of glucose molecules bonded to each other) and is found in small amounts (~5-10 grams total) as free glucose in the bloodstream.  Liver glycogen exists primarily to help maintain blood glucose levels while glycogen within skeletal muscle can only be used by the muscle that it’s stored in; it can’t be released back into the bloodstream.

Dietarily, traditionally carbohydrates have been divided somewhat simply into two major categories (this is especially true in athletic subcultures but is often used generally) which are fibrous and starchy.  Please note that this is mainly a division of convenience but it tends to be useful practically so I’ll stick with it.

Fibrous carbohydrates generally refers to vegetables which, with a few exceptions, tend to contain very small amounts of digestible carbohydrate while containing a lot of fiber.  Pretty much any vegetable you care to name (with the handful of exceptions mentioned next) will fall into this category of carbohydrates and it’s often stated that you can eat these types of carbohyrates ‘without limit’ due to their generally low caloric content.  I’ll come back to this shortly.

Starchy carbohydrates are, more or less, everything else: breads, pasta, rice, and grains, basically any carbohydrate that contains a good bit of digestible carbohydrate. I should note that there are a few starchy vegetables such as carrots, peas, corn and potatoes: vegetables which contain larger amount of digestible carbohydrate and which need to be counted as starches in terms of real-world meal planning.  Fruits, while not technically a starch, are usually grouped with starches since they contain quite a bit of digestible carbohydrate (the majority of which are simple sugars).

Explaining the caloric value of carbohydrates can be somewhat confusing. Starchy carbohydrates are generally assigned an average value of 4 calories per gram (16 kj/g) although this can vary slightly from food to food.   Fiber is where it gets more confusing; as I recently discussed in Fiber – It’s Nature’s Broom, some types of fiber can be broken down to other things in the intestine and, recently, fiber has been given a caloric value of 1.5-2 kcal/g (~6.3-8.4 kj/g).  While this isn’t a large amount given most people’s average fiber intake, for people who are eating enormous amounts of vegetables (which don’t just contain fiber, mind you), the calories can start to add up.

And with those topics covered, I’ll stop here for today.  On Thursday, I’ll take another quick look at dietary fats along with the ‘everything else’ category of human nutrition: alcohol, vitamins, minerals and fiber (again).

What seems to have happened is that one person stated that certain ideas were true and a bunch of people who didn’t know any better simply started repeating those ideas until they became an accepted ‘truth’.  Unfortunately, science says different and that’s what I’m going to look at.

The most common one that seems to be constantly repeated is that if you eat the same food (usually protein since most true food allergies are caused by proteins) continuously, you can give yourself an allergy to that food.  This happens to be utterly wrong as I’ll show below.

There are other silly ideas, one of the dumbest I’ve seen of late is that you can cure a food allergy by not eating that food for 6 weeks.  This is not only wrong but potentially fatal.  True food allergies (again, I’ll discuss what this means in a second) never go away; if someone has a true allergy to a food, they can’t ever eat that food again for all practical purposes.

Actually, that’s not entirely true, one weird study showed that children with peanut allergies could eventually get to where they could eat half a peanut but it took months and months of feeding them like 1/4 peanut to get them to that level.  Hooray.  For all practical purposes, a true food allergy never goes away and the idea that abstaining from that food will make it go away is simply absurd.

Since most food allergies occur in response to protein foods, I’m actually going to simply be excerpting the section from The Protein Book about food allergies and intolerances.  For anybody who’s interested, I’ve included the references cited in this section at the end of the article.

Food Allergies and Intolerances

To finish up this chapter, I want to make a few comments about food allergies and intolerances, which I touched on above in the section on dairy foods. Commonly, the terms food allergy and food intolerance are used interchangeably although they actually represent very different phenomena (40).

Food intolerance, such as lactose intolerance from dairy products, typically occurs due to a lack of appropriate digestive enzymes and this tends to cause upset stomach, gas, bloating or diarrhea. At worst, food intolerances typically cause some discomfort but no real danger.

In contrast, a true food allergy generates an immune reaction in the body. This is potentially much more severe and can cause respiratory, stomach, skin and cardiovascular symptoms; anaphylactic shock and death can also occur in extreme cases (40). True food allergies are typically caused when small amounts of proteins enter the bloodstream. This can occur during childhood when the gut lining isn’t fully developed or later in life due to a compromised stomach barrier. Some allergens can also enter the body through the respiratory system.

While technically any food can cause a true allergic response, protein foods tend to be the most common culprits with milk, egg, peanuts, tree nuts, some fish and shellfish being the most common causes of allergies (41). Gluten, a protein found in grains such as wheat, barley and rye, is also a common source of food allergies (42). Gluten allergies can be especially troublesome for athletes with high caloric and carbohydrate requirements since grains cannot be consumed; increasing commercial availability of gluten free foods can help to ensure adequate calorie and carbohydrate intake.

True food allergies are thought to occur in 3-4% of adults. There are a number of different ways to determine the presence of a true food allergy but, from a practical standpoint, if eating a given protein source causes problems of the sort described above, that tells the athlete all they need to know. For the most part, there is little to no treatment for true food allergies; avoiding the problem food is the best and only option (40).

References:

40. Ortolani C and Pastorello EA.  Food allergies and food intolerances.  Best Pract Res Clin
Gastroenterol. (2006) 20(3):467-83.
41. Sicherer SH and Sampson HA.  9. Food allergy.  J Allergy Clin Immunol. (2006) 117(2
Suppl Mini-Primer):S470-5.
42. Schuppan D et. al. Celiac disease: epidemiology, pathogenesis, diagnosis, and
nutritional management.  Nutr Clin Care. (2005) 8(2):54-69.

Summing Up

So hopefully the section above helped make the distinction between a food intolerance and a true allergy.  True food allergies are rare and can be fatal like any true allergic reaction.  Eating that food causes a massive immune response and this can cause people to drop dead.

This is not a joke, children with peanut allergies who are given a food with even trace amounts of peanuts can go into anaphylactic shock, have trouble breathing and can die.  Contrast this to when someone has a lactose (milk) intolerance, drinks a glass of milk and gets real gassy.  They are not the same thing but people confuse them all the time.

As well, food intolerances are reported at something like ten times their actual rate of occurrence; people eat something and don’t feel good and assume they have an intolerance when they really don’t.

And, as discussed above, true food allergies don’t occur because you eat a given protein source too often.  An allergy occurs when a bit of undigested protein gets into the bloodstream and causes the body to mount an allergic reaction to it via the immune system.  Since the gut lining is set up to avoid this, the only way that a true food allergy can usually occur is if the gut lining is compromised.  Under those conditions, small pieces of undigested proteins can slip through into the bloodstream and that’s when the problems start.

Various disease conditions can cause this to occur (and as noted children with undeveloped gut linings can develop food allergies because of it) but this pre-existing condition has to exist for a true allergy to develop.  For example, there is a condition called leaky gut syndrome which is exactly what it sounds like, the gut leaks stuff into the bloodstream; this can cause all kinds of problems.

And once a true food allergy exists, it’s yours forever.  The immune system is amazing in this way, remembering how to mount a response to offenders basically forever (this is the basis of immunization of course, give the person a small case of a certain disease so that the immune system ramps up, and then they can fight off that disease in the future).   So once you have a true food allergy, you have it for life.

It is certainly not my area of expertise but people who fear that they may have a food allergy can get explicit testing for it done.  However, as I noted above, if you eat something and nearly die, you know all you need to know anyhow.  This is true at least in the case of severe food allergies.  Of course, it seems that it is possible to have mild food allergies (which are probably more like intolerances) and getting tested for those may be useful if someone suspects a problem.

If for no other reason, food intolerances seem to be able to generate a stress response and this appears to cause water retention in some people (in addition to just generally not feeling very good.  I have a hunch that the whole idea of ‘eating foods you’re ‘allergic’ to stops weight loss’ is probably due to this mechanism: you start holding water due to a stress response and it masks fat loss.

First I want to define energy density before looking at some examples that will hopefully make the concept a bit more clear.  Finally, I’ll look at applications of the energy density concept in terms of dieting, weight gain, etc.

What is Energy Density?

Conceptually, energy density refers to how many calories are found in a given weight or volume or food.  Ok, what does that mean. Let’s say that you have 1 gram of each of the three macronutrients which are protein, carbohydrates and fat.  We know that these are given calorie values of 4 cal/g for protein and carbs and 9 cal/g for fat.  Clearly, in this simple example, fat has over twice the energy density of either carbs or fat (9 cal in one gram vs. 4 cal in one gram).

This basic fact is generally interpreted one of two ways depending on whether a given author is pro- or anti-fat (and of course what the context is).  Pro-fat authors will contend (usually in the context of exercise performance) that since fat contains twice the calories of carbohydrates, it provides more energy to the body on a gram per gram basis (again, the context is usually exercise performance).  While there is an element of truth to this it leaves out some important information that I’m not going to get into in this article.

In contrast, anti-fat authors (usually coming at it from an obesity or weight gain standpoint) tend to blame high caloric intakes (and hence obesity) on a high fat intake because of it’s high energy density.  That is, frequently diets higher in fat are also higher in calories because of the increased energy density.

But Wait…

Unfortunately, just looking at things as simply as above is misleading for the reasons I outlined in Calories, Nutrients or Food?.  First and foremost, people don’t generally eat pure nutrients, they eat food.  And, as discussed in that article, most foods are a combination of nutrients (e.g. milk contains protein, carbs and fat, meat contains protein and usually fat, most carb sources contain some protein).  Even in those cases where folks (read: OCD athletes) may choose pure nutrients, most humans eat mixed meals containing multiple foods and that affects the overall energy density of the meal.

Of perhaps more relevance is that most foods also contain other non-nutrient compounds such as air, water, ash, fiber, etc.  Put differently, 100 grams of say chicken won’t contain 100 grams of protein; rather, the amount of protein will be diluted by the presence of not only other nutrients but the other compounds that are present.

If this is difficult to understand, an easy example might be soup which is mostly water.  So say you make a soup containing potatoes, vegetables, ground beef, some vegetable oil, spices and what have you.  Each of the foods you put in will contain some amounts of carbohydrates, proteins and fat and each will fall somewhere in terms of their energy density.  However, a cup of that soup will likely have a fairly low energy density because most of the volume is water.

Another example would be to compare two cups of pasta to one cup of pasta with one cup of steamed vegetables.  Both meals are 2 cups (in terms of the total volume) but the second meal would contain far less calories due to the vegetables; and since the total volume of both meals is the same, the energy density (calories per unit weight/volume) would also be lower.  In this specific case, the low energy density food dilutes the higher energy density food and brings the overall energy density of the meal/dish down.

Alternately, let’s take a typical 100 grams baked potato which contains about 46 grams of digestible carbohydrate; hopefully readers can sort of imagine about how big that would be (this is just a standard size baked potato).  Now contrast that to 100 grams of pure table sugar which will contain very nearly 100 grams of carbohydrate; I bet you can imagine just how little sugar that would be.

In both cases we’re looking at 100 grams of total food but the caloric content of each is drastically different (about 200 calories vs. 400) as is the energy density.  The potato will have an energy density of 200 calories/100 grams food compared to the 400 calories/100 grams food in the table sugar.

Of course, 100 grams of pure fat would contain nearly 900 calories and still have the highest energy density of all.

Here’s an example that will help to illustrate just how large a role water content plays in all of this.  Two cups of grapes will contain about 100 calories while 2 cups of raisins (dried grapes) might contain nearly 800 calories.  This is because the raisins have had most of the water and air content removed during the drying process.  Same volume, same food, but drastically different energy densities.

One thing I would note is that, although fat is often blamed for the high-energy density of the diet, this isn’t always true.  Food companies have come up with amazingly creative ways to make low-fat high-carb foods be exceedingly energy dense by removing water, air and fiber.

Most dietetics types seem to assume that a high-carb diet will be non-energy dense but they are assuming that people are eating naturally occurring carbohydrates such as potatoes; in the real world this is rarely the case.  When you start moving into heavily processed carbohydrates, the energy densities can get up there pretty quickly.

As a general rule, foods high in water and fiber tend to be pretty low on the energy density scale and food that lack either tend to be much higher.  Pure oils tend to have the highest energy densities (which is why I strongly recommend measuring them out, even if you don’t measure anything else in most of my books) and vegetables tend to have the lowest, everything else is somewhere in the middle.

Why Does This Matter?

Ok, enough explanation, why is this important.  Energy density starts to become important when you are looking at food intake in the real world, both in terms of dieting and gaining weight (for athletes).  A lot of this has to do with fullness and satiety, a topic I discussed somewhat in 9 Ways to Deal with Hunger on a Diet.

Some research suggests that humans eat a fixed weight of food each day (other research says this is not the case and I’ll let the scientists argue it out for the time being); thus people who eat higher energy density foods invariably end up eating more total calories. Basically, if you are going to eat 2 pounds of food per day (I’m pulling this number out of thin air), you will end up consuming more calories if you eat high energy density foods vs. low energy density foods.

Even if this isn’t entirely the case, high energy density foods tend to make it easier to overconsume calories compared to low energy-density equivalents.  This is especially true when you’re looking at uncontrolled diets (e.g. where people are not tracking calories), a topic I keep harping on but one that people keep confusing with other issues of the diet.

Simply put, foods with a low energy density will contain a relatively small number of calories in a large bulk or volume of food.  As noted above, vegetables, fruits and other unrefined carbohydrates typically have a low energy density although even that’s not always the case as mentioned above

Foods with a high energy density will contain a large number of calories in a relatively small amount of food. This generally includes high-fat foods but can also include highly refined carbohydrates. I mentioned this above but I want to look at that issue in a little more detail.

It looks at first glance that high fat foods will always be more energy dense than similar amounts of carbohydrates or protein and that fact has been used as part of the campaign to lower dietary fat to help with the obesity problem. But is this always the case, are high-fat foods always higher energy density than high-carbohydrate foods?

Let’s take our baked potato example, containing about 46 grams of carbohydrate in a 100 gram potato. So it contains about 200 calories/100 grams. Let’s say we add 10 grams of fat in the form of butter (making anti-fat crusaders cringe) to the potato which adds 90 calories. Our potato/butter combination contains 290 calories in 110 grams of food.

Now let’s contrast this 110 grams of candy and let’s say it contains ~100 grams of sugar, or 400 calories. So the baked potato/butter combination contains 290 calories/110 grams of food while the candy contains 400 calories/100 grams of food.  Despite being ‘high-fat’, the potato-butter combination has a lower energy density than the zero-fat high-sugar food its being compared to.

Semi-tangentially, while the anti-fat crusaders tend to blame high-fat diets for every malady known to man, there are real-world examples, such as the classic Mediterranean diet (which often contains up to 40% fat as total calories), where a high-fat diet doesn’t cause problems.  Much of this is that the overall diet is still fairly low energy density because there are a tremendous amount of vegetables being eaten.

Despite having a high fat content, the Mediterranean diet has an overall low energy density because of the other foods that are present in such abundance.  This is in contrast to most Western diets that tend to not only be high in fat but low in foods such as fruits and vegetables that would dilute the energy density of the fat.

As I mentioned above, one of the reasons that fat is so often blamed for its role in causing obesity is its high energy density. This is obviously true if you’re talking about pure fat (which few people eat) and it’s generally true that high fat foods have a high energy density. This difference is especially prevalent if they are compared to low-fat unrefined carbohydrate foods likes fruits, vegetables and unrefined grains. You know, the foods that nobody really eats but that anti-fat crusaders think people are eating.

As I alluded to above, a low-fat diet isn’t automatically a low energy-density diet. Many highly refined high-carbohydrate foods have a high energy density because the water, air, fiber, etc. has been removed. More and more, food companies have brought low-fat/high-carbohydrate but also high energy density foods to market.

Even diet staples such as pasta can have a surprisingly large number of calories in a fairly small volume. Such foods may be low (or even no) fat but still have a very high energy density. This not only makes them easy to overconsume but also means that they can contribute a rather large number of calories to the diet without providing much bulk.

To really drive this into the ground, a high-fat diet isn’t automatically a high energy density diet any more than a low-fat diet is automatically a low-energy density diet. The types and amounts of other foods in the diet play a major role and, in my experience, what dietetics types think people are eating in the real world isn’t what people are actually eating in the real world.

Which isn’t to say that an excessive fat intake isn’t contributing to the energy density (or caloric content) of the modern diet; of course it is. Dietary fat simply isn’t the only factor contributing to the problem of caloric overconsumption.

So Which is Better?

You may be thinking after the above discussion that choosing a low energy-density diet is always superior.  If you’re talking about weight loss or even general health, there is probably much truth to that.  For people who won’t or aren’t going to count calories, choosing low energy density foods will tend to reduce caloric intake without doing anything else.  For people on a diet, foods with a lower energy density tend to be more filling, helping to keep hunger at bay.

But there are exceptions to this.  Often times, people want or need to gain weight (especially athletes).  In that situation, when very high caloric intakes may be required, low energy density foods can actually make it impossible to get in sufficient calories.  Admittedly, this probably isn’t a situation that applies to the majority but it does come up.  Trying to get 6000 calories per day eating nothing but low energy density foods can be a near impossibility and consuming higher energy density foods may be necessary to get the job done.

A related issue are the high-carbohydrate refeeeds that I recommend in my books (such as A Guide to Flexible Dieting and The Rapid Fat Loss Handbook).  When the goal is to deliberately overconsume a lot of carbohydrates, people invariably get into trouble trying to do low-energy density, high-fiber foods.  Not only can’t they get sufficient calories in to make the refeed worthwhile, but the high-fiber tends to make them explode (if you get my meaning).  Similarly, in the post-workout period, higher energy density foods may be preferred due to a faster rate of digestion and the hormonal response.

And, of course, for people who are actively tracking calories, some of the above becomes much less relevant.  As I discuss in Is A Calorie A Calorie?, much of this type of stuff only really matters when people aren’t tracking calories (because of the impact of different food choices on spontaneous food intake).  For people who do track daily calories, clearly some higher energy density foods can be worked in (if desired) because total calories will still be controlled.

Reviewing basic physiology

On a day to day basis, your body has certain nutrient requirements, a topic which is discussed in detail elsewhere in this book. As described in those chapters, those nutrient requirements are generally related to how much you weigh (or how much lean body mass you have). There are a few exceptions, places where the requirements for a given nutrient are absolute which I’ll mention when necessary.

For example, at any given moment, nearly all of the tissues in your body are utilizing some amount of protein for various processes. Your liver, your kidneys, your muscles, your fat cells, your gut are all using protein for protein synthesis and energy needs. Meaning that the more of those tissues you have, the more protein you need; the less of those tissues you have the less protein that you need.

The same goes for carbohydrate and fat. Your body is using energy at some rate (set by your metabolic rate which is fundamentally related to your body mass but also determined by factors such as hormones, the temperature and other factors) and that means providing energy at some level related to bodyweight. Since carbohydrate and fat are your body’s primary energy yielding nutrients, that means that they are required in some amount related to bodyweight. In addition, fat is being used for other structural processes and is going to be required in some amounts relative to bodyweight as well. And although those values may change (based on activity and other factors such as genetics, age, etc.), they are still going to change relative to your bodyweight. Some numerical examples:

The RDA for protein is set at 0.8 g protein/kg body weight (0.36 g/lb) while dieters may need as much as 1.5 g/kg (0.68 g/lb) to avoid excessive protein loss. Endurance athletes need protein at roughly 1.2-1.4 g protein/kg (0.54-0.63 g/lb) and weight trainers may need 1.6-1.8 g protein/kg (0.72-0.81 g/lb). Most bodybuilders use 1 g/lb as a rough estimate and this isn’t too far off from the value of 0.8 g/lb.

So someone who weighs 200 lbs and is sedentary needs about 72 grams of protein per day; if they were dieting, they’d need at least 136 g/day; if they are an endurance athlete, they need between 108-126 grams of protein per day; if they are weight training, they may need 144-164 grams of protein per day. Note, at this point, that I’ve said nothing about percentages.

And while there’s no true requirement for carbohydrates, studies show that maintaining daily endurance performance may take 5 g carbohydrates/kg (2.2 g/lb); glycogen supercompensation requires amounts on the order of 10 g carbohydrates/kg (4.5 g/lb).

For the most part, fat intakes in relation to bodyweight haven’t really been determined, and most research still simplistically talks in terms of percentages. A minimal intake of 3-6 grams of linolenic acid, and 1-2 grams of linoleic acid has been suggested to avoid deficiency syndromes. As discussed elsewhere, whether this represents an optimal amount in terms of health or body recomposition is debatable. Even then, it seems impossible that some fixed amount of either linoleic acid or alpha-linolenic acid would apply to everyone regardless of bodyweight.

But this is all sort of tangential to my point which is that nutrient requirements are related to your bodyweight or lean body mass.

Why is this a problem?

So why is this a problem? When someone puts protein, carb, or fat requirements in terms of percentages only for a diet setup, it doesn’t necessarily have any relevance to what that person actually needs. For example, it’s not uncommon to see diets for bodybuilders set up with 25-30% protein. Others take a more conservative 15% and use that across the board for athletes or general intake. But what do those percentages actually mean? Obviously nothing unless you also know how many calories that person is eating.

Let’s use our 200 lb example individual above and look at his protein intake. Let’s split the middle value for weight training and say he actually needs 150 g/day of protein and put him at two different caloric extremes: 1000 cal/day (a starvation diet) vs. 10,000 calories/day (Parillo style). Let’s set protein at 30% which most would say is sufficient (or excessive depending on who you’re talking to).

1000 cal/day at 30% yields 300 calories from protein, or 75 grams of protein. He’d need 60% protein on 1000 cal/day to get 150 grams of protein per dya. 10,000 cal/day at 30% yields 3000 calories from protein, or 750 grams of protein. Although both diets are 30% protein, the first is half of what our guy actually needs (75 g/day vs. 150 g/day); the second diet has 5 times as much protein as he actually needs. Yes, these are extreme examples and deliberately chosen that way. But they point out that the percentage itself has no relevance whatsoever to what our guy’s actual requirements are.

Now, the typical counter-response to what I wrote above is that the percentage values are assumed to be based on some fairly average caloric intake. That is, if we were to put our 200 lb guy (150 g/protein required per day) on a more ‘average’ 2400 cal/day (12 cal/lb) and 30% protein, he will come out with a protein intake of 2400 * 0.3 = 800 cal from protein yielding 200 grams/day or 1 gram per pound. Yes, a little higher than the 150 g/day but not excessively so. And that’s fine, percentage based diets are going to be roughly valid within a certain caloric range. The problem is that isn’t always how they are applied and that’s certainly not how the percentages are typically interpreted.

More problems: interpretation and usage

It’s quite common to see statements of “Such and such is a high-fat diet and hence bad.” or “High-protein diets are bad”, things of that nature. Most commonly, those statements are based on the percentages of a given nutrient in a diet. For example, diets containing 30% or less total calories from fat are generally considered ‘low-fat’ while, by definition, higher fat intakes are considered high-fat. But this can be terribly misleading as well as misused. Here’s an example.

Let’s say we have a person who’s currently eating 2000 calories of which 150 grams (600 calories) are protein, 176 grams (707 calories) are carbs, and 77 grams (693 calories) of fat. Using the math from the last chapter, this yields a diet that is 30% protein, 35% carbohydrate, and 35% fat. Most would refer to this as a high-fat diet and deem it bad because it contains 35% fat calories. They would probably also call it ‘low-carbohydrate’ and ‘high-protein’ based on the percentages.

Ok, so let’s say we add 200 grams (800 calories) of carbohydrates (let’s use table sugar just because) to the diet without changing anything else. Total calories now go to 2800 and the percentage of calories from fat drops 35% to 25% (protein drops from 30% to 21%, carbs increase from 35% to 53%), even though the total fat intake in grams hasn’t changed. By typical naming conventions a ‘high-fat’ diet has now magically become a ‘low-fat’ diet and nobody will have a problem with the protein or carbohydrate intake, based on the percentages. Of course, total fat intake in grams didn’t change. Neither has protein intake in grams. All we did was skew the percentages by adding 200 grams of table sugar to the diet. And I don’t think anybody would argue that adding 200 grams of table sugar to this diet is particularly healthy. Yet many clueless folks would automatically assume or claim that the second diet (25% fat) is healthier than the first (35% fat) because it’s a ‘low-fat’ diet even though both diets contain the same number of grams of fat.

On a related note, many food companies will use this strategy as well. By simply adding table sugar to a food, to increase the caloric content, they can drive the percentage of calories from fat downwards below 30% and call it a low-fat food. You can make vegetable oil (100% fat calories at 14 grams fat/140 calories) a low-fat food if you add enough table sugar to it. Does that make it healthy because it’s now ‘low-fat’? Obviously not. Or perhaps not so obviously because some folks fixate so hard on the percentages that they miss the forest for the trees.

Using the same starting diet from above, say we decide to take all of the carbohydrates out of the same diet. Now it contains 150 grams of protein (600 calories), zero grams of carbs, and 77 grams of fat (693 calories) and 1293 total calories. Now it contains 46% protein and 54% fat. Most would call this a high-protein, high-fat diet and go into an apoplectic fit even though it contains the exact same number of grams of protein and fat as the previous diet. By simply changing the total carb and caloric content, we can skew the percentages. But we haven’t changed a damn thing in terms of absolute protein or fat intake.

Or an even more extreme example, let’s say we decide to move this guy to nothing but protein (as in my Rapid Fat Loss Handbook). Now he’s eating nothing but 150 grams of protein per day. That’s a 100% protein diet, which most would call ‘high-protein’. First they’d freak out, then they’d tell you that his kidneys are going to fall out of his ass. Except that it contains no more and no less protein than the previously two described diets; once again, by manipulating the total caloric content of the diets we’ve changed the percentages even if we really haven’t changed the gram intake.

On that note, this is a common criticism of ‘low-carbohydrate’ and/or ‘ketogenic diets’. Most will call them high-protein and/or high-fat because the percentage of total calories from protein and fat is very high. But this can be misleading because ketogenic diets are also commonly low in total calories. Studies typically show that total protein and fat intake change very little when people move to ketogenic diets. Rather, total calorie and carbohydrate content come down, and the percentage from fat and protein go up. Nitwit diet critics will look at the high fat percentage and condemn the diet, without looking at the actual gram intake.

Another example: one of the popularly referenced studies by lower-carbohydrate diet advocates refers to a group of athletes given only 40% of total calories from carbohydrates, who are able to maintain performance. This is frequently used (by low-carbohydrate diet proponents) to argue that a diet of 40% carbs is sufficient and/or that ‘high-carb’ diets are unnecessary. Here’s the problem: because of the extremely high total caloric intake in these athletes, 40% of total calories still yielded in excess of 400 grams of carbohydrates per day (a far cry from the 150-200 grams/day you might get on a typical lowered-carb diet). So even though it was ‘low-carbohydrate’ by percentage standards, it was still high-carbohydrate relative to their bodyweight needs. Even at only 40% total calories, they still got close to the 5 g/kg value listed above needed to sustain glycogen stores. Once again, the percentage had absolutely no relevance to the actual gram intake.

And, finally, here’s a rather humorous example from my college days. At some point or another, during a nutrition class, a professor of mine had made the rather common statement that “As long as you don’t eat foods with more than 30% total fat calories, you will be fine” something to that effect. It seemed like a logical extension of trying to get total fat intake below 30%: make sure no individual food contains more than 30% fat calories and you should be safe. At some later date, I took him a cookie recipe of mine that contained approximately 20 calories/cookie and 1 gram of fat (the cookies were mostly air, with a little sugar and some chocolate chips). My professor bristled, because these cookies contained nearly 50% of calories from fat (9 calories out of a total 20). Well, yeah, but they still only contained 1 gram of fat/cookie. ONE GRAM. A cookie that was 200 calories and 30% fat (70 calories) would contain 8 grams of fat even though it’s below the magical 30% cutoff point. Yet he would have considered the second a better food choice based on just the percentage even though it had 10 times as many calories and 8 grams of fat vs. 1. Go figure.

Making my point

Looking simply at the percentages of a given nutrient contained within a diet or food can lead people down entirely incorrect paths. Whether it’s in setting up a diet, on intrepreting a given diet, looking at the percentages alone is a mistake. A 15% protein diet might contain too much protein if calories are absurdly high, and far too little protein if the calories are very low. And a diet which contains ‘only’ 40% carbohydrate may contain more than enough actual carbohydrates by grams as long as the total caloric intake is high enough. A diet which was considered ‘high-fat’ by percentage can be made ‘low-fat’ by simply adding carbohydrates/calories/sugar to the diet but that’s not necessarily improving anything.

As I pointed out early in this chapter and elsewhere, daily nutrient requirements are (generally) based on bodyweight, not the percentage of that nutrient in a diet. If someone requires, say, 1 gram of protein per pound of bodyweight, they need 1 gram per pound whether it represents 10%, 50% or 100% of their total calories. If someone needs 5 g/kg of carbs to maintain performance, that’s what they need whether it’s 40% of their total calories or 60% of their total calories. If they need X grams of fat (X not really having been established at this point except for minimal essential fatty acid requirements), they need X grams no matter the percentage. Are we clear now on the different between percentages and total grams? I certainly hope so.

In this article, I want to teach readers what these percentages mean and how to use them (if you so desire) either analyze a given diet, set up a diet, or figure out what a food label means.

A quick recap on calories

In a previous chapter I gave you the caloric content of the various macronutrients. To save you needless paging, I’ll review them here.

• Protein: 4 calories/gram
• Carbohydrate: 4 calories/gram
• Fat: 9 calories/gram
• Alcohol: 7 calories per gra

Calculating percentages

With the above values in hand, and using some basic math, we can do several different operations in terms of diet and food analysis. Let’s look at each one in turn. I’ll give examples but don’t read too much into the numbers. They are only examples.

Operation 1: Setting up diets based on percentages

Probably the most common use of methods is to do actual diet set up, to determine how many grams of each nutrient someone will be consuming. Let’s say we have a 170 pound male with a maintenance calorie level of roughly 2700 calories per day and let’s say we wanted to put him on a diet that was 60% carbohydrate, 20% protein and 20% fat (again, don’t read too much into these values, I’m using them for example only). We want to find out how many grams of each nutrient he will be consuming per day.

Step 1: Calculate total calories of each macronutrient

The first thing we’d do is multiply his total caloric intake (2700 cal/day) by the percentages of each macronutrient as this will tell us how many calories will be coming from each nutrient. To convert percentages, just divide by 100 so 20% becomes 0.20, 60% becomes 0.60, etc.

The calculations appear below

• Carbohydrate: 2700 * 0.60 = 1620 calories from carbohydrate
• Protein: 2700 * 0.20 = 540 calories from protein
• Fat: 2700 * 0.20 = 540 calories from fat
• Note: It should be obvious that the percentages need to total 100% (or 1.0).

Step 2: Determine total grams from each macronutrient

Now we simply divide the total calories from each macronutrient by the caloric content of each macronutrient. This tells us how many grams of each food our guy will be eating each day.

• Carbohydrate: 1620 calories / 4 cal/gram =405 grams carbohydrate
• Protein: 540 cal / 4 cal/gram = 135 grams protein
• Fat = 540 calories / 9 cal/gram = 60 grams fat per day

So this particular diet, with 2700 calories and 60% carbs, 20% protein and 20% fat yields a diet of 405 grams of carbohydate, 135 grams of protein and 60 grams of fat per day. For the remainder of the diet setup, you’d divide that up across some number of meals including pre- and post-workout, all that jazz.

Operation 2:
Working Backwards Part 1: Determining Diet Composition

You can just as easily work the math backwards, to determine what percentage of each nutrient a given diet is. Let’s say someone was eating 150 grams of protein, 200 grams of carbohydrate, and 50 grams of fat and we want to find out how many total calories they are eating and what the percentages of the diet are.

Step 1: Determine caloric intake

First you simply mutiply the total grams of each nutrient by the caloric content of that nutrient. That tells you how many calories they are eating each day

• Protein: 150 grams * 4 cal/gram = 600 calories from protein
• Carbs: 200 grams * 4 cal/gram = 800 calories from carbs
• Fat: 50 grams * 9 cal/gram = 450 calories from fat
• From those values, you can calculate total daily caloric intake by simply adding up the numbers.
• Total calories = 600 + 800 + 450 = 1850 calories per day.

Step 2: Determine percentage from each nutrient

Now simply divide the calories from each nutrient by the total number of calories being consumed to determine the percentage each nutrient is providing. Multiply the decimal amount by 100 to get the percentage

• Protein: 600 calories/1850 calories = 0.32 * 100 = 32%
• Carbs: 800/1850 = 0.43 * 100 = 43%
• Fat: 450/1850 = 0.24 * 100 = 24%.

So our example person is consuming 1850 calories per day with 32% from protein, 43% from carbs and 24% from fat.

Operation 3:
Working Backwards Part 2: Determining Food or Meal Composition

You can use the identical math above to determine the composition of a given food (based on the food label) or a given meal.

So say you wanted to determine the macronutrient percentages on a food or a meal that contained 10 grams of protein, 20 grams of carbohydrates, and 9 grams of fat.

Step 1: Determine calories from each nutrient

First you’d simply multiply the total grams of each nutrient by the caloric content of that nutrient.

• Protein: 10 grams * 4 cal/gram = 40 calories
• Carbohydrate: 20 grams * 4 cal/gram = 80 calories
• Fat: 9 grams * 9 cal/gram = 81 cal

Although most food labels list the total caloric content, even if they don’t, you can easy figure it out by adding up the totals above. This food/meal would contain 201 calories (40 cal + 80 cal + 81 cal)

Step 2: Determine percentages from each nutrient

Now you simply divide the total calories from each nutrient by the total calories in the food.

• Protein: 40 calories/201 calories = 0.2 * 100 = 20% calories from protein
• Carbohydrate: 80 calories/201 calories = 0.4 * 100 = 40% calories from carbohydrate
• Fat: 81 calories/201 calories = 0.4 * 100 = 40% calories from fat

So this food or meal would contain 201 calories, with 20% protein, 40% carbs and 40% fat. Whether those percentages mean anything is the topic of the next chapter

A note on food labels

Many people become perplexed when they do the math above on food labels and find that the caloric content listed isn’t the same as what they calculate. So you might see a food that was listed as containing 212 calories with 10 grams protein, 20 grams of carbs and 9 grams of fat (which, as above, only yields 201 calories). There are a couple of reasons that this happens.

The first is that determining the caloric content of a given food isn’t doesn’t give perfect values, there is always a little bit of slop. As well, the 4, 9 and 4 cal/g values are rounded values in the first place. Finally, food labels almost always round off the values for protein, carbs and fat grams (for example, a food containing less than 0.5 g of fat can list it as 0 grams of fat). If the food listed above actually contained 10.5 grams of protein (44 calories), 20.5 grams of carbs (84 calories) and 9.5 grams of fat (85 calories), that would make up for the difference in values.

Ultimately, these types of tiny differences are no big deal. Even under the best circumstances, caloric estimates are only estimates and there’s always going to be a little bit of slop either direction. We’re not doing clinical nutrition here and, as long as it’s not excessive, small discrepancies in calore values are nothing worth worrying about.

In Diet Percentages: Part 2, I’ll explain why I think using percentages to set up diets is a mistake.

Examining Both Sides of the Debate

As noted, the usual argument goes that high-fat diets cause high-cholesterol, heart disease, cancer, obesity and the rest, as evidenced by the high incidence of those disease in modern diets (which are typically high in fat). But that’s a questionable conclusion to draw.

Modern diets are also high in carbohydrates (and mainly the highly refined, high GI, low-fiber stuff that the body often doesn’t handle well), low in fruits and vegetables, and generally contain the wrong types of fats (an excess of saturated and trans fats with insufficient amounts of healthy fats). Such an intake is typically coupled with inactivity, the folks eating them tend to be overweight/obese, smoking and alcohol play a role, etc. That is, there are a number of inter-related factors at work here.

Pinning the blame entirely on fat intake or expecting only a reduction in fat to fix the problem is disingenuous: there are a lot of variables at work here. Some research suggests that the entirety of the problem rests with excessive saturated fat intake with the other variables (activity, fruits and vegetables, etc.) playing a relatively minor role. It’s awfully hard to tease out all of the relationships when there are this many variables at play.

Similar comments can be made in terms of obesity. Fat is more calorically dense than carbohydrates and studies comparing high-fat (40%) to low-fat (25%) meals find that people tend to eat more in the higher fat conditions; this is usually referred to as passive over-consumption and leads to excess calorie intake. These studies have problems, mind you, but that’s beyond the scope of this article. The point does stand, though, that dietary fat is tasty (giving food mouth feel) and folks do tend to eat more of foods that taste good.

But while it’s common to blame obesity on high-fat diets, not all researchers agree. Some cultures have fairly high fat intakes but have no problems with obesity and researchers are starting to realize that fat isn’t the ONLY problem. Increasing intakes of refined carbohydrates (contributing large numbers of calories to the diet), decreasing activity, increasing portion sizes and other factors all contribute. You can’t dismiss an excessive fat intake as part of the obesity problem; it’s simply not the sole factor. I don’t want to get into a massive discussion of the carb versus fat debate in terms of caloric intake, preferring to focus on the health issues here.

The fact is that not all studies link a high fat intake to an increased risk of disease. For example, recent analyses of our ancestral diet (what we ate during 99.9% of our evolution) suggests a much higher fat intake and much lower daily carbohydrate intake. Exact numbers vary depending on what assumptions you use but carb intakes of 20-40% (most of which came from low GI, high fiber fruits and vegetables; grains were almost non-existent), fat intakes of 28-60% (which had a significantly different quality than our current diet), and protein intakes of 19-35% of total calories are the current best estimates.

Studies of extant hunter-gatherer societies show little incidence of any of the diseases of modern society and it’s thought that our evolutionary diet was NOT atherogenic (promoting heart disease) despite the high fat intake.

The reasons for this are many-fold, of course and that’s the key to keep in mind when you consider fat intakes and potential health problems. In our ancestral diet, fiber intakes were monstrous, averaging 100-150 grams per day. As well, despite the high fat intake, the source of that fat was far, far different than our modern intake. Much higher intakes of polyunsaturated and mono-unsaturated fats and far lower intakes of saturated fat were fairly typical. Activity levels were also much higher and folks generally stayed pretty lean. Alcohol intake was low or non-existent, as was smoking. Although our ancestors dealt with various stresses, they didn’t deal with the kinds of chronic stress that occurs in modern societies.

Related to this, studies of the Mediterranean diet have found few problems in terms of heart disease and all the rest despite a relatively high fat intake (40% of total calories). Although the reasons are, as always, multi-factorial some of the contributing factors are that the fat intake is primarily from mono-unsaturated sources (e.g. olive oil).

As well, a tremendous amount of fresh vegetables are typically consumed (with far less reliance on refined carbohydrates). Other factors such as activity, bodyweight, moderate alcohol intake and lowered stress levels probably play a role. Studies of the Alaskan Inuit show similar results, despite an extremely high-fat intake, heart disease is almost unheard of. This has typically been attributed to the high intake of fish oils but there may be genetic adaptations as well.

Of course, some studies on low-carbohydrates diets (which are typically high in fat) will show a big improvement in blood lipid levels; this is especially true for individuals with insulin resistance. I’d note that this effect primarily occurs when weight is lost; in studies of very low-carbohydrate diets where weight is gained, blood lipid levels often get much much worse.

Thus, whether or not you’re gaining or losing weight probably impacts on whether or not dietary fat is a health risk. I’d note that studies in cyclists find that high intakes of saturated fat don’t pose a health problem as long as the athletes are in calorie balance. As I mentioned above, activity (which will affect whether ingested dietary fat is stored or burned off) plays a big role here.

Studies in diabetics are finding that higher mono-unsaturated fat intakes (and lowered carbohydrate) intakes may be healthier than the converse. This, of course, only holds if calories are strictly monitored and controlled to avoid weight gain. When weight is gained, from nearly any dietary approach, blood sugar control in diabetics worsens.

Of course, there’s a flip side to the anti-fat dogma and reducing fat to extreme levels can cause its own set of problems. First and foremost, most people find extremely low-fat diets to be tasteless and this tends to limit adherence in the long-term (as I mentioned above, high-fat diets tend to be very tasty and people frequently eat too much).

And while caloric intake typically goes down in the short-term, folks frequently end up increasing caloric intake because they are hungry all the time. Dietary fat slows gastric emptying (keeping food in the gut longer) although some work suggests that this effect is lost with chronically high-fat diets. Extremely low-fat diets tend to leave people hungrier for this reason.

There is also evidence that the fat-soluble vitamin absorption may be impaired when fat intake is taken too low. And while total cholesterol typically decreases when fat intake is lowered, the decrease occurs in both the good (HDL) and bad (LDL) sub-fractions so overall health risk may not be improved. From a body recomposition or performance standpoint, some studies show a lowering of testosterone with very low fat diets.

There is another set of issues that crops up as well. Again, it relates to the simple fact that people have to eat something. In reducing fat intake, most people increase carbohydrate intake. Most researchers would say that this is just fine as long as the increase comes in the form of unrefined, high fiber, complex carbohydrates. I would say that most researchers need to get out of the lab and look at the real world for a while.

The simple fact is that the majority of people who reduce fat do NOT increase carbohydrate intake from unrefined, high-fiber, complex sources. This is especially apparent in the US (I can’t speak for other countries) where companies rapidly jumped on the ‘fat is bad’ bandwagon and brought tons of ‘low-fat’ high-carbohydrate sources that were highly refined to market.

Such foods may have as many, if not more, calories than the same higher-fat items. Even when they don’t, humans play a cute psychological game, tending to eat more of a given food when they are told it’s low or no-fat.

Recent studies are finding that, when carbs are increased from those sources, other problems show up. In addition to the changes in blood cholesterol I mentioned above (both the good and bad subfraction decrease), the increase in refined carbohydrate intake causes an increase in blood triglyceride levels and small LDL particles; both of which are independent risk factors for heart disease and all the rest. The chronically high insulin levels which commonly occur with such a diet cause other problems including insulin resistance and all of the issues that accompany it.

I should probably note, and this could certainly be an entirely separate article, that the new scapegoat for obesity and all of the health problems in the world is excessive carbohydrate intake, with a lot of the focus on insulin release. I don’t have space here to address that side of the argument, a future topic for another day.

Sufficed to say that while there is certainly an element of truth to this (in that excessive intakes of any nutrient, and that includes refined carbohydrates, is bad), it’s still true that simplistically arguing that ‘fat is good and carbs are bad’ is just as moronic as arguing that ‘carbs are good and fat is bad’. Again, it depends on the context.

Summing Up

Now, I want to make it very clear that I’m not trying to make this either a pro-fat or anti-carbohydrate article or trying to make a low-carbohydrate diet the default choice for anybody. My point is simply that the idea that ‘fat is bad’ and ‘carbs are good’ (or the opposite) is too simplistic to be meaningful.

Not all fat is bad and not all carbs are good. The source, the composition of the rest of the diet, the total amounts you’re eating of each, your activity level and other variables all factor in. Whether you’re talking about health risk or obesity, you can’t simply pin the blame on one factor or the other.

So, under conditions of high caloric intake, with a high intake of refined carbohydrates (meaning chronically high insulin levels), poor quality fat choices (too much saturated fat and/or too little unsaturated fats), little activity, minimal fruit and vegetable intake, etc. a high-fat intake is probably very detrimental from a health standpoint. Sadly, this describes a fairly typical diet in the modern world (especially the US).

In contrast, with reduced or even controlled caloric intake (such that bodyweight goes down or is maintained) and most of the fat coming from unsaturated sources (note: excessive polyunsaturated fats has its own set of problems), a high fruit and vegetable intake, reasonable activity levels, keeping body fat levels down, etc. higher fat intakes may be no problem at all. In some situations, an increased fat intake (again, from healthy sources within the context of activity and a high fruit and vegetable intake) may be beneficial compared to the alternatives (e.g. increasing carbohydrate intake).

In this article, I want to look at carbohydrate and fat intake in terms of the various arguments and debates that tend to surround them.

The main controversy here revolves around what amounts of carbohydrates and/or fat are ideal, healthy, recommended, etc. and that’s what I’ll focus on. I’m not going to deal with body composition explicitly in this article, I’ll save that for another day.

Two (or Three) Dietary Camps

Generally, folks fall into one of two camps regarding whether they think carbohydrates or fats are good or bad. For a couple of decades now, the mainstream of dietary advice has been more or less stuck in the mindset of ‘fat is evil and ‘carbohydrate is good’.

Various attempts to promote so-called ‘high-fat’ or ‘low-carb’ diets have usually been shot down as fads although there is increasing research evidence that, at least for some individuals (usually those with insulin resistance) higher fat intakes and lowered carbohydrates may be both beneficial and preferred.

However, for the most part, I’d say that mainstream dietitians are still on the carbs = good, fat = bad bandwagon with higher fat/lower carbohydrate diets being relegated to the diet ‘fringe’.

Both groups can bring impressive (or at least impressive looking) data to the table but, as usual, extreme stances are invariably incorrect and the truth lies somewhere in the middle; this particularly debate is no different.

The third group (and the one I put myself in) recognizes that whether or not carbohydrates or fats are ‘good’ or ‘bad’ depends on the context. The source of the carb or fat, the rest of the diet, the goal of the individual, genetics, activity, etc. all factor into this issue. So while it may be convenient to give simplistic recommendations of the ‘X is bad, Y is good’ variety, simple in this case tends to be incorrect.

Perhaps the most succinct way of describing what I’m going to detail is that there are no good or bad foods only good or bad diets. That is, within the context of one type of diet or individual situation, a specific food may be excellent; under other conditions it may be a poor choice.

What does the Body Require?

So that some of my comments will make sense, I need to cover a smidgen of nutrient physiology, mainly having to do with the issue of carbohydrate ‘requirements’ (a topic I cover in detail in How Many Carbohydrates Do You Need).

As I think I’ve managed to work into every book I’ve ever written, there is no strict physiological requirement for carbohydrates (this factoid is often used by the low-carb diet groups as part of the rationale for their dietary approach).

Most tissues in the body can readily use fatty acids for fuel just as easily as glucose. There are a few tissues such as the renal medulla, red blood cells and one or two other that can only use glucose. However, those cells essentially make their own glucose by recycling lactate (produced from glucose metabolism) back into glucose.

The brain is in its own weird category. Under most conditions, it relies exclusively on glucose. And while it can’t use fatty acids directly, it can use a fatty acid derived fuel in the form of ketone bodies. After roughly three weeks of adaptation to using ketones, the brain may only need 25 grams/day of glucose or so, which can be made by the body (in the liver and kidney) from sources such as lactate, pyruvate, amino acids and glycerol.

Even the American Dietetic Association bible, the RDA Handbook, states that there is no requirement for dietary carbohydrates. Any decent nutrition or physiology book will state the same. Despite this basic biological fact, many researchers and diet authorities still insist that the majority (50-60% or more) of the human diet should come from carbohydrates.

I’ve seen papers where researchers point out that the body requires no carbohydrates which then go on to say that a proper diet should contain at least 50% carbohydrates. It doesn’t make much sense.

At the same time, outside of a small essential fatty acid requirement (a few grams per day from the fish oils, EPA/DHA), fats aren’t truly required by the body either. All of the tissues I mentioned above will use glucose if you provide it (the heart is an exception, almost exclusively relying on fatty acids for fuel) and the body can make fatty acids out of other sources if need be (this pathway isn’t utilized massively in humans, although a few conditions will make it relevant).

So, outside of the small essential fatty acid requirement, one could make an argument for there being no physiological requirement for fats either.

What does the body then require on a day to day basis if there is no real requirement for either carbohydrates or fats? Well, outside of the basics like water and air, roughly eight amino acids are essential to get from the diet, there’s the small essential fatty acids requirements and of course vitamins and minerals. Everything else, strictly speaking is optional.

I would note that, to avoid starving to death, sufficient calories will be required. Since it’s generally unrealistic to consume your entire daily caloric requirement from protein, that means that carbs, fats, or a combination of the two, will generally be needed to supply sufficient energy to the body.

But, as noted above, most tissues in the body show a great deal of flexibility, using carbs when they are available and fats when carbs aren’t available. Note also that the body has its own store of fuel, primarily in the form of body fat that is mobilized when sufficient amounts of other nutrients aren’t available.

So Why Do Most Argue that Carbs are Good and Fats are Bad?

Despite the fact that there is no physiological requirement for carbohydrates in the human diet, the most common dietary recommendation in modern times is generally to reduce fat intake and increase carbohydrate intake. I’m going to address the issue starting from that standpoint.

A good question might be why is this stance taken. While I can’t read the minds of these folks (and I hate to contribute to grain lobby USDA conspiracy theories), I think the reasons is actually fairly simple: we have to eat something.

There’s usually a limit to how much protein can be reasonably consumed (and most authorities seem to be against ‘high’ protein intakes as well) so that means that the rest of the diet (in terms of energy) must come from either carbohydrate or fat.

In the 70’s, the stigma against dietary fat started to develop and it all pretty much went from there. Fat was implicated as the cause of heart disease, stroke, obesity, you name it and excessive fat intake was blamed.

Since people have to eat something and because of the general stigma against a high fat intake (some of which is warranted, some of which isn’t), policy makers recommend a high-carbohydrate intake by default.

The bigger question is whether or not this is a scientifically defensible position.

I’ll address this issue in more detail in Carbohydrate and Fat Controversies: Part 2