Two questions please:
1. Is this OK?
2. Is there anyway to eliminate the smell?

Answer: This is a fairly common report on very low-carbohydrate/ketogenic diet (defined, once again, as any diet containing less than 100 grams of carbohydrate per day), a report of a fairly strong ammonia smell in the sweat during exercise.  As I discuss in detail in my first book The Ketogenic Diet this ammonia is produced due to the ultimate breakdown of ATP to ADP to AMP and ammonia.  

This appears to occur more readily when muscle glycogen is depleted (as occurs with the combination of of a very low-carbohydrate intake along with training) and may be part of the increased protein requirements that have been known to occur with endurance training (this is discussed in detail in The Protein Book).  I would mention that it appears that this ‘protein breakdown’ is not actually coming from the breakdown of skeletal muscle itself; rather it’s from the breakdown of BCAA (branched-chain amino acids) within the free amino acid pool.

So is this ok?  So long as dietary protein intake is sufficient, I don’t see this as being any real problem.  The effect is slight in terms of the absolute amount of protein being broken down (in terms of grams) and so long as protein intake is sufficient, there shouldn’t be any detrimental effect other than the smell.

And how do you get rid of the smell?  Well, either wear strong deodorant or raise your carbohydrate intake above the ~100 g/day cutoff point so that you’re not in ketosis.  That’s really all I’ve got solution wise since it’s just one of those biochemical processes that is going to occur during long-duration workouts on a ketogenic diet.  All the best!

However, I’m significantly overweight (6′ 220; ~35% body fat by a cheap scale) which is obviously a contributor to the diastasis. You can see why the idea of rapid fat loss is attractive.  The thing is, for the first 6 weeks on the diastasis program, strength
training is out of the picture.  I’m doing my cardio on a VersaClimber, which at least works my legs fairly well.

Would the rapid fat loss protocol work OK under these conditions? It sounds as though to try it I would need to put in more time on the climber and skip the intervals for the duration.

Answer: The short answer is that, at your current body fat percentage, yes, the Rapid Fat Loss Handbook program can be done without weight training.  This is an issue that I discuss in the book as well as in the article Initial Body Fat and Body Composition Changes but, simply, the higher your initial body fat percentage, the less muscle you are likely to lose under any circumstances (and by extension the leaner you are the more muscle you tend to lose, although this depends on a host of variables).   The primary function of resistance training on any diet is to maintain muscle mass (as discussed in Weight Training for Fat Loss Part 1 and Weight Training for Fat Loss Part 2) but when the risk of muscle mass loss is reduced, the importance of weight training is lessened.

An additional factor, also discussed in the book is that there is often an increase in lean body mass (and this represents both muscle mass and connective tissue) when people gain body fat.  From the standpoint of obtaining a ‘normal’ body weight (whatever ‘normal’ means here) losing that ‘extra’ LBM is thought to be beneficial or necessary by some obesity experts.

Finally, at least in relative beginners, even cardiovascular exercise (and the Versaclimber is one of the rare machines that has both an upper and lower body component) has some effect on sparing muscle mass loss.  So the inclusion of that (although with volumes cut back to match the recommendations in the book) should be sufficient until you abdominal issue has healed and you can begin resistance training.

Hope that helps and good luck!

Answer: I think you’re referring to the article I wrote on Why Big Caloric Deficits and and Lots of Activity Can Hurt Fat Loss, although I may have addressed the issue in a Q&A as well (I can’t find it).  In any case, your question is one that comes up fairly frequently, especially in the context of the Rapid Fat Loss Handbook approach (where I am adamant that excessive activity/cardio can cause the diet to work far less well than expected).  People want to know what and how much of certain types of activities will or won’t cause problems.

The primary issue here is this: the body appears to be sensing what researchers are calling energy availability, basically energy in (from food) versus energy out (via energy expenditure as discussed in detail in Metabolic Rate Overview).  And if energy availability becomes too low, often bad things (in metabolic terms) happen.  For example, researcher Ann Louckes has shown that many of the issues that often occur in women in terms of hormones or menstrual cycle dysfunction occur at a threshold of energy availability (and aren’t actually related to body fat percentage as used to be thought).

In that sense, pretty much all activity can potentially be a problem if that activity results in an energy availability to the body that is too low.  Of course the activities you’re listing aren’t really big calorie burners, a walk with a stroller probably only burns a few hundred calories per hour.  But done for extended periods it will contribute.

A related issue, and one I focused on more in Why Big Caloric Deficits and and Lots of Activity Can Hurt Fat Loss can be related to both intensity and volume.  In addition to hormonal issues, often the combination of big caloric deficits and excessive activity (either too much activity, too hard of activity, or the combination) can cause some real weirdness with water retention that masks fat loss.

I’d tend to say that this is more common with more formal ‘cardiovascular’ activities than just activities of daily living.  This is just due to the potential for increases in hormones like cortisol; this is especially an issue as the intensity of activity increases.  Clearly this isn’t an issue for a leisurely walk but it becomes more of one for more formal cardio activities.

This isn’t really stopping fat loss mind you, but it does drive people crazy because it makes it appear that the diet is not working.  I’d note that this isn’t an issue for everyone, certain physiologies (and especially psychologies) seem relatively more prone to problems with water retention than others.  This is why some people can get away with massive amounts of activity and not have issues and others can’t.

In any case, I hope that answers your question to at least some degree.

Basically, his method was to weigh himself everyday. If he was under his target weight, he’d eat two meals. If over, he’d just skip his last meal. He takes a protein shake w/ 100g whey and makes sure he hits at least 1g/lb of LBM everyday.  Will this work for recomposition?

Answer: While I have no clue what or who a wave_length is, here are my answers.  Short answer: no, this won’t work.

Long answer: This is stupid on so many levels I’m not sure where to start.

First and foremost, as I discussed in What Does Body Composition Mean? the whole point of using body composition methods is that body weight per se generally can’t tell you much of anything.  There are exceptions of course: in the extremely obese for example, most weight loss will be fat assuming a few criteria (basic weight training, protein) are met.   In that case, the scale is sufficient since weight losses will indicate fat losses.

But for lean and/or trained individuals, body weight changes alone tells you literally nothing because a change in weight might represent a change in any number of things: muscle, fat, water, glycogen, you took a big dump, you didn’t take a big dump, etc.  A change in weight doesn’t tell you anything meaningful.

I addressed this in some detail in Measuring Body Composition Part 1 and Measuring Body Composition Part 2.  In any case, this is problem one with this approach: scale weight is basically useless to track actual body composition changes under most circumstances.

Problem two is this: day-to-day changes in weight aren’t meaningful under the majority of circumstances.  Some examples to make this clear: if you’re on a low-sodium diet and you eat some pizza or something salty, your weight will spike the next morning.  But it’s all water weight.  Eat less vegetables on a given day and your weight will go down after you take a dump because you have less food residue in your colon.

Gorge on high-fiber, high-residue foods and your weight will go up because you have more waste moving through your colon.  Cut carbs a lot and you will drop water like a mad-man and weight will plummet.  Do a high-volume glycogen depleting workout and the same can happen.  Do the workout with low carbs and body-weight can drop by a number of kilos from water loss.  A coach/friend of mine uses this approach with athletes who need to make weight, he can drop 1-2.5 kg off of them in a matter of HOURS with the combination of lowered carbs and a hard glycogen-depleting workout.

All of these can acutely affect weight on a day to day basis but NONE of them are indicative of actual changes in muscle mass or fat mass (which happen on a longer time scale under most circumstance especially in the lean and/or trained).  Not to mention that the previous day’s adjustment is going to affect the next day’s scale weight measurement anyhow.  If you skip dinner on a day when your weight is up, you’re going to weigh less the next morning BECAUSE YOU SKIPPED DINNER and have less food in your gut.  But it’s got nothing to do with actual body composition changes.

The bottom line is this: adjusting your diet daily based on scale weight changes is simply an idiotic way to do anything; all you’ll do is spin your wheels by adjusting calories up and down and up and down in a pointless fashion based on a meaningless measurement that is being affected by the wheel spinning caloric adjustements days to day.  A far better approach is what I describe in Adjusting the Diet.  Do that instead of following the nonsense above.

Question: I suppose a follow-up question to this answer is just how rare it would be to cross a true “point of no return” where you may have fouled up your internal physiology to where it may never be able to rebound. Or is it usually a case of time and reversing some of the actions that cause it in the first place? i.e. the longer and more extreme the descent, the longer it will take to recover, but recovery is entirely possible

Would clinically severe eating disorders probably be the only instances where someone could allow things to devolve to such a degree that any sort of irreparable damage may have been done to some part of the body and its normal functioning?

Answer: First let me say that I am not and do not claim to be any sort of expert on the topic of eating disorders.  It’s simply not been a major area of interest of mine.  I think it’s worth considering that what is going on in something like anorexia or bulimia is quite different than what is going on with the topic I was primarily addressing in the original Q&A, to wit contest diets in bodybuilders/physique athletes.

For example, if nothing else we can see massive differences in the nutritional intake of a dieting bodybuilder/physique competitor (typically based around high protein intakes and ‘healthy’ foods) as opposed to the near complete absence of food in the anorexic or the alternation of binging and purging in the bulimic.

With that said, what little literature I have looked at in terms of recovery from eating disorders doesn’t lead me to believe that there is any sort of permanent damage.  So long as a ‘normal’ weight is regained (here we’re typically looking at the anorexic), things come more or less back to normal.  Even in the seminal Minnesota study, metabolic rate eventually rebounded to normal; of course the subjects had regained all of the fat they had lost as well for that to occur.

But again, this is really outside of my major sphere of interest; if anyone reading this has expertise that can contribute to this question, I think we’d all love to see it.

Question: Layne Norton once said that from the day one begins to eat normally again, it can take anywhere from 3-4 months to completely restore BMR to 100% from post-dieting levels. Although he didn’t cite it, do you know of any studies roughly reflecting this extended time frame? I’m only referring to restoration of normal hormone output and, thus, adaptive thermogenesis, since if the weight loss were maintained, BMR would still be relatively lower than it was pre-diet simply by virtue of a lower final body weight.

Answer: No direct research on this comes to mind immediately although it may exist. I think the problem is that, usually in looking at post-diet ‘recovery’ there is almost always a regain in body fat which tends to color the issue.  For example, in the Minnesota study that I mentioned in the question above, following the 6 months of semi-starvation, the men were allowed to eat as much as they wanted.  And they went nuts, eating massive numbers of calories and regaining fat.  Which normalized metabolic rate eventually but doesn’t really apply to what you seem to be describing.

Frankly, I’m not 100% sure that hormones will ever return to completely normal (see next question) assuming that the lowered body weight/body fat level is maintained. They can be improved by raising calories to maintenance for sure.  This is part of the rationale behind The Full Diet Break although that’s really meant to break up periods of explicit dieting (I also suggest it at the end a diet to start normalizing things).  Which is a long way of saying “I don’t know”  If Layne has a reference for that, I’d love to see it.

Question: So there is evidence of metabolic derangement, but do you think it is permanent even when returning to normal caloric intake?

Answer: The studies of the post-obese (see next question) suggest that, even at weight maintenance (i.e. when calories have been returned to normal), there is still a small overall reduction in basal metabolic rate (on the order of perhaps 5%) compared to someone who is ‘naturally’ of that weight.  Meaning that if you compare someone who is 180 pounds without dieting to someone who has dieted down to 180 pounds, the second person will show a slightly reduced metabolic rate compared to the predicted values.  But the effect is slight when calories are brought back to maintenance.

As I discussed in the original Q&A, it looks like the main impact in terms of reducing daily energy expenditure is on spontaneous activity levels; this probably explains why exercise seems to have so much bigger of an impact on weight maintenance than weight loss (as I discussed in Exercise and Weight/Fat Loss Part 2).

I am unaware of any research examining if this is maintained in the long-term (i.e. will the post-obese continue to show decreases in spontaneous activity).  However, the long-term studies of the post-obese (ranging from 2-5 years if my memory serves correctly) suggest that the effect on basal metabolic rate never goes away.  So yes, it’s effectively permanent; it’s simply small.

Question: I’m also wondering about the permanence of any such metabolic adaptations. It seems likely to me that metabolism would return to normal at some point. If so, how long would it take? It seems like I read something about this in a discussion of the Minnesota study, but I’d have to go searching to see if I’m remembering correctly.

Answer: As noted in the question above, what data I’ve seen looking at the post-obese in the long-term suggest that there is a slight reduction in basal metabolic rate that doesn’t appear to ever go away.  At least not in any practical time frame.  Based on what we know about the issue of setpoint (discussed in Set Points, Settling Points and Bodyweight Regulation Part 1) I wouldn’t expect this to ever truly go away.   I imagine someone will ask the logical followup to this in the comments which is “So what about people who get and stay lean in the long-term, how do they do it?”  Maybe addressing that will get me past my writer’s block to write an actual article about it.

Question: I am a clinical nutritionist at clinic where we see a lot of people with “screwed up metabolisms”. In a different vein, there are the people who got fat from overeating and eating the wrong types of foods and became insulin resistant. Now they have to eat low calorie diets otherwise they gain weight.

One of my clients weighs 360 lbs and her BMR according to the the InBody is 2700 calories. The girl eats maybe 1200 calories a day and maintains that weight. Reversing insulin resistance by eating the proper foods and incorporating resistance training obviously helps. I am wondering if there is an approach to increasing calories systematically when working to reverse insulin resistance without gaining weight?

Answer: This is really a bit outside of what the original Q&A was discussing but I’ll address it anyhow; certainly there can be metabolic derangements that occur in obesity (what’s cause and what’s effect is often hard to determine).  However, it’s highly unlikely that your client is truly maintaining her weight on 1200 calories per day if her measured BMR is that high (meaning that her total daily energy expenditure is even higher); insulin resistance or not, that’s simply a physiological impossibility.

The more likely (and exceedingly common) issue is that she’s simply consuming more food than she’s aware of or self-reporting.  Because even in studies of insulin resistance, when calories are reduced (and and accurately monitored), weight/fat loss occurs.  So either she’s a physiological anomaly or she’s not really eating 1200 calories per day.  And my experience (along with a large body of research) suggests that it’s the latter issue that’s the cause of the problem.

Thanks for the questions folks!

This sounds like bro-hype but I’m wondering: Is there any truth to this phenomenon?

Answer: This seemed a good followup Q&A after last Friday’s Lean Body Mass Maintenance and Metabolic Rate Slowdown – Q&A since it’s semi-related and I seem to have total writer’s block regarding anything approximating a feature article right now.

There are several issues at stake here and I’m going to address them in reverse order.  Certainly I have seen some weirdness occur (and there is at least one study to support this) where excessive cardio in the face of a large caloric deficit can cause problems, not the least of which is stalled fat/weight loss.  In that study, the combination of a very large deficit plus about 6 hours of cardio seemed to decrease metabolic rate more than the diet alone. This is something I intend to cover in more detail at a later date.

This, along with personal observations, was what led me to strongly suggest against doing a lot of cardio on The Rapid Fat Loss Handbook program; in fact I’d say that a majority of failures on that program can be tracked to people trying to do too much cardio and it doing more harm than good.   Invariably, the folks who minimize activity (beyond the basic weight workouts) and let the deficit of the diet do the work do better in terms of fat loss.  So certainly there is an element of truth to that.

However, we need to look at magnitudes here and do a bit of reality checking. Several in fact.

The first is to look at the food intake.  700-900 calories is not a lot of food and, typically, at the end of a contest diet, hunger is simply off the map.  I find it doubtful that someone is truly consuming that little food on a day to day basis at the end of a contest diet.

Note that I did not say impossible (anorexics certainly seem to do this); I’m simply doubtful that someone is consuming that little food in the face of extreme hunger on a day to day basis.  They may be reporting that that is their true food intake but I’d be doubtful that it was truly that low on an everyday basis.

Now, as discussed in the Q&A I linked above (as well as in other articles on the site and in my books), there is no doubt that the body undergoes a variety of rather annoying adaptations to reduced calories and fat loss.  Reduced metabolic rate, reduced spontaneous activity, etc. all occur and this works to slow fat loss.  But what we’re really dealing with here is a magnitude issue.

First and foremost, if someone is claiming to get fat on only 900 calories per day, that implies that their actual total daily energy expenditure is actually LESS than that. That is, as I discuss in some detail in The Energy Balance Equation, we know that to actively gain fat requires a caloric surplus (relative to expenditure).

To gain fat at say 900 calories, and to do so at any fast rate would imply that daily energy expenditure was significantly less than that.  For example, assume that someone eating only 900 calories per day were gaining fat at a rate of 1 pound per week.  That would imply a 500 cal/day surplus or a total daily energy expenditure of 400 calories per day.

For an average sized male who started out with a maintenance energy expenditure of 2700 calories per day that would be an 85% reduction.  For an smaller female who started with perhaps a 1700 calorie/day maintenance, that would be a 75% reduction from where they started.  And simply, that level of reduction is far and beyond everything that’s ever been measured in the history of research on this topic.

Now, some might argue that the stressors of competition dieting haven’t been examined and they’d probably be right; to my knowledge, no-one has examined the metabolic rate of a bodybuilder following an extreme contest diet.  Quite in fact, most studies don’t examine lean individuals at all but there is one study that is possibly relevant which is the seminal Minnesota Semi-Starvation Study.

I’ve talked about this study before and it represents one of the most massively well-controlled studies on the topic ever done (or that will ever be done).  In it, war objectors were placed on approximately a 50% reduction from maintenance calories (which only put them around 1500 calories/day or thereabouts in the first place) and were held there for 6 straight months.  Activity (walking) was enforced and most men reached the lower limits of body fat percentage by the end of it.  I’d note that only men were studied so it’s possible that women, who are prone to showing more resistance to fat loss, could show a differential response.

And the total reduction in daily energy expenditure only amounted to 40% (of which the majority of that was due to the weight loss).  Weight and fat loss had basically stopped at the end of the study which makes sense; the original 50% deficit had been reduced to at most 10% due to the 40% reduction in metabolic rate.

The bottom line is that no study I’ve ever seen has suggested that total daily energy expenditure could be reduced to the levels that are implied by ‘gaining fat rapidly at 700-900 calories/day’.

So what’s going on?  Certainly some bad hormonal things go on when you combine heavy activity with heavy deficits for extended periods to low body fat levels (I’d note that various types of cylical dieting such as my own Ultimate Diet 2.0 and Martin Berkhan’s Intermittent Fasting approach seem to side-step at least some of this).   Thyroid levels drops, nervous system output drops, testosterone levels crater, cortisol goes through the roof.

And I would suspect/suggest that it is this last effect that is being observed and taken as evidence of ‘metabolic damage’.  In a water depleted, glycogen depleted bodybuilder coming out of a contest diet, water balance is going to go absolutely crazy and cortisol is one mediator of this.  Water retention secondary to glycogen storage will also contribute.

So you have a situation where a post-contest bodybuilder may be seeing just massive swings in water weight (which can appear like rapid fat gain) following the contest; especially when you consider the normal runaway hunger that tends to occur at that point.

Between glycogen storage and simple cortisol mediated water retention, I can’t see any other reason to explain the observation.  Even one day of overeating carbs can cause massive water retention (for example, shifts in water weight of 7-10 pounds over a day or two are not uncommon on cyclical diets) and I suspect that’s what is being observed.

Which is all a long way of saying the following: certainly there is evidence of metabolic derangement when you diet people down to low levels of body fat, this can probably be made worse if you undergo the normal severe overtraining cycle that most dieters go through at that point.  But I don’t see any physiological way that true rapid FAT gain can occur at such low calorie levels.  I’d suspect that water retention (and a bit of neurosis equating water weight gain with true fat gain) is the primary culprit here.

Is this a faulty assumption? I’ve read on many a website that the body goes into “starvation mode”, however that argument doesn’t sit well with me. Either the body requires X amount of energy to function, or it doesn’t. I think “starvation mode” might simply be reduced activity in general, so for a relatively insane individual (read:athlete) who is willing to push hard on a restrictive diet, metabolic slowdown shouldn’t be an issue?

Answer: I suspect that some of this comes down to an issue of semantics (you sort of get to part of what I’m going to talk about in your second paragraph) but some of it doesn’t.  The short answer to your question is that your assumption isn’t entirely correct; even with 100% maintenance of lean body mass (LBM) there can still be some metabolic slowdown.  Now here’s the longer answer.

First and foremost, we need to define some terms and what’s meant by metabolic rate since I suspect that’s part of where some of the confusion is coming from.  On a daily basis, an individual’s total daily energy expenditure is given by three components, which I’ve discussed in detail in Metabolic Rate Overview. They are

1. Resting/Basal Metabolic Rate (RMR/BMR; what I suspect you’re referring to above)
2. Thermic Effect of Food (TEF)
3. Thermic Effect of Activity (TEA)

Where TEA has now been divided into two distinct components: the thermic effect of exercise and non-exercise activity thermogenesis (NEAT).  The distinction being that the first is calories burned during formal exercise and the second, NEAT, is the calories burned during activities such as daily moving around, fidgeting, moving from sitting to standing, etc.  I discussed the potentially major impact of NEAT in a recent research review on Role of Nonexercise Activity Thermogenesis in Resistance to Fat Gain in Humans.

Now, each of the above is determined by various factors including body composition, diet, etc.  And all of them are affected by dieting and the loss of body mass.  Studies have repeatedly shown that individuals who have been dieted down to a given weight will have a lower than predicted metabolic rate compared to someone who didn’t diet to that weight.  That is, someone who ‘naturally’ weighs 200 pounds will have a higher total energy expenditure than someone who dieted down to 200 pounds.

So what’s causing this reduction in total energy expenditure.  A majority of the ‘metabolic slowdown’ that occurs is due simply to the loss of body mass.  Because larger bodies burn more calories (both at rest and during activities) and smaller bodies burn less.

But that’s not the only cause of metabolic slowdown here.  There is also an adaptive component of metabolic rate slowdown that is mediated by changes in hormones: leptin, insulin, thyroid, catecholamines.  As these change (decrease) on a diet, you find that tissues burn fewer calories per unit mass.  I’d mention that not all studies find this, about half do and half don’t.  That is, your assumption that a given body composition always burns the identical number of calories on a day to day basis isn’t entirely correct.

Of course, an important question is how much of a change this amounts to.  During active weight loss, the impact is relatively greater (because hormones tend to be more greatly affected); at weight maintenance (once a person has stabilized), the impact isn’t huge.  In some studies of the post-obese (folks who have been dieted down and maintained at that weight) show a relatively modest 5% or so reduction in RMR.  The effect exists but is not massive; it’s also highly variable, with people showing relatively more or less of an effect.

There is also evidence that individuals move around less when they lose/are losing weight.  As James Krieger recently wrote on his Weightology.net website, it looks like changes in activity (especially NEAT) are the far larger contribution to the reduction in overall energy expenditure on a day to day basis; the number of calories burned in that activity also appear to be reduced due to improved muscular efficiency.

In that study, decreases in RMR were about 150 calories per day but reductions in activity expenditure were up in the 300 calorie plus range with the total effect being over 400 calories.  This is likely why daily activity has such a profound impact on weight maintenance as I discussed in Exercise and Weight/Fat Loss Part 2: since the body is ‘automatically’ decreasing activity energy expenditure, you have to make up for it.

So basically you’re both correct and incorrect.  The greatest impact on total daily energy expenditure certainly appears to be due to decreased spontaneous activity during the day. However, there is also an added component of a reduction in resting energy expenditure due to changes in RMR, even with complete maintenance of lean body mass.  Some of this is due to simply being smaller, some of it is an adaptive reduction in metabolic rate due to shifting hormone levels (which, again, not all studies find).

And semi-tangentially, a long while back I had written an article as a background primer to something I had intended to write about alcohol.  Well, now I don’t have to since Martin Berkhan over at Leangains.com has written it.   In his article The Truth about Alcohol, Fat Loss and Muscle Gain he pretty much covers everything you could ever want to know about the topic.

Answer: The short answer, as you might have guessed is no.  Now, as always, here’s the longer answer.

I suspect that the idea that one needed to eat fat to burn fat came out of a misunderstanding of some of the early literature on low-carbohydrate/high-fat/ketogenic diets (note: I’m defining a ketogenic diet here as any diet that contains less than 100 grams of dietary carbohydrate; a topic discussed in more detail in my first book The Ketogenic Diet).

In those studies, there was clearly an increase in the body’s use of fat for fuel (indicated by a large scale decrease in something called the respiratory exchange ratio or RER) and I have a hunch that people assumed that it was the huge increase in dietary fat that was driving the increase in fat burning.

But as I discussed in Nutrient Intake, Nutrient Storage and Nutrient Oxidation as well as in How We Get Fat, the burning (oxidation) of fat isn’t really related to fat intake per se.  Rather, it’s related to carbohydrate intake.  That is, the act of eating dietary fat doesn’t usually have a major impact on how much fat you burn.   I say ‘not usually’ as some studies find that very high fat intakes (like 80 grams all at once) have a small effect on fat oxidation by the body. But for the most part, how much fat the body burns during the day is related primarily to carbohydrate intake, secondarily to protein intake, and almost not at all to dietary fat intake itself.

Also consider that the following three conditions:

1. Complete fasting (no food intake at all)
2. A high-fat, low-carbohydrate ketogenic diet (e.g. 30% protein, 65% fat, 5% carbohydrate)
3. A protein sparing modified fast (PSMF, such as my own Rapid Fat Loss Handbook)

All generate basically the identical shift in the body’s fuel utilization: a decrease in resting RER indicating a shift to using predominantly fat for fuel.  Again I say basically since both the ketogenic diet and the PSMF will be marginally different than complete fasting due to the intake of dietary protein.  But for the most part, the shift in fuel use by the body is identical in all three conditions, you see a huge drop in RER indicating a massive increase in the use of dietary fat for fuel.

And the commonality in all of those conditions is not the presence or absence of dietary fat (diets 1 and 3 have little or no dietary fat, diet 2 has quite a bit).   Rather, it’s the lack of dietary carbohydrates.   Which, based on what we know about how the body determines fuel usage makes sense.  As I discussed in the linked articles above, when you eat more carbs, you burn more carbs (and less fat); eat fewer carbs and you burn fewer carbs (and more fat). Which means that in all three conditions above it’s the absence of dietary carbohydrates driving the increase in fat burning, not the presence of dietary fat.

Which isn’t to say that increasing dietary fat intake under some conditions can’t have benefits (such as increased fullness, food enjoyment or flexibility, limiting the daily deficit to moderate levels if that’s the goal, etc.) which are discussed in other articles on the site (I’d suggest the Comparing the Diets series for an overview of different dietary approaches).  It’s simply that increasing fat burning per se simply isn’t one of them; rather, that’s accomplished by reducing carbohydrates and total caloric intake.

Hope that answers your question.

Answer: The above question actually came through in the comments section of Exercise and Weight/Fat Loss: Part 2 and I thought it was important enough to address explicitly since it’s a place where I still see many mainstream diets and dieters making mistakes.   It’s worth noting that bodybuilders and other strength athletes have been promoting higher protein intakes while dieting for decades and this is yet another place where modern science has ended up validating those beliefs many years after the fact.

The question of adequate protein under different conditions is one that has a long history of debate, the issue of maintenance requirements as well as protein intakes for athletes is still highly debated with science on both sides of the story (for details you can refer to The Protein Book).

With regards dieting specifically, this was a topic of much study in the 60′s and 70′s as researchers started looking past the simple issue of weight loss and into that of changes in body composition; the goal moved from weight loss per se to that of generating fat loss while minimizing lean body mass and muscle mass loss.

After much toing and froing and research had been done it was eventually found that a protein intake of about 1.5 g/kg of lean body mass (LBM; note that researchers actually used Ideal Body Weight but this is a rough proxy for LBM) was necessary to spare LBM losses in a non-training obese individual consuming low calories.

This is about double the DRI for protein (at 0.8 g/kg) at maintenance calories.  So for an overweight individual at say 200 pounds and 30% body fat (this would give them an LBM of 140 lbs or 63 kg), that would be a protein intake of 95 grams of protein per day.   Please note that this value is simply a minimum and dieters may still find that higher protein intakes are beneficial from a hunger blunting effect or what have you (see below).

In that context, I’d mention that at least one of the studies I referred to in Exercise and Weight/Fat Loss: Part 2 that found no benefit of resistance training gave something like 40 grams of protein to the subjects; far less than necessary or adequate.  So it’s no surprise that no protein sparing effect of exercise was seen; the diet was inadequate in the first place.

It’s worth noting that more recent research supports further benefits of increased protein intakes while dieting, beyond simple lean body mass maintenance.  Protein is the most filling nutrient (meaning that higher protein intakes tend to control hunger better) and studies have found that higher protein intakes can help to stabilize blood sugar levels while dieting which has benefits from both an energy level and appetite standpoint.  Protein high in the amino acid leucine (with the dairy proteins whey and casein being the two proteins highest in leucine) seem to have extra benefit in this regard.

Now, as individuals get leaner, protein requirement tend to go up further for reasons discussed in other articles on this site.  As well, regular training tends to further increase protein requirements.  So lean athletes trying to lose fat while sparing lean body mass loss need even higher protein intakes than this.  And we’ve known for decades now that caloric intake per se tends to impact on protein requirements; as caloric intake goes down, protein requirements go up. And vice versa.

While less data on this group is available, bodybuilders and athletes have long used a protein intake of 2.2 g/kg (1 g/lb) lean body mass as a generalized intake level and as folks get very lean, intakes of 3.3 g/kg (1.5 g/lb) of lean body mass may be required to stave off muscle loss while dieting.  In some very extreme cases, such as the near protein only diet approach of my own Rapid Fat Loss Handbook even higher protein intakes may be required for very lean individuals.

So basically we have an intake continuum ranging from about 1.5 g/kg (0.68 g/lb) as a minimum for the obese non-training individual up to a high of around 3.3 g/kg (1.5 g/lb) of protein per pound of lean body mass for very lean heavily training athletes or bodybuilders with middle ground values being found in between those two extremes.  You’ll note that I didn’t put any of those values in terms of percentages for reasons discussed in Diet Percentages: Part 1 and Diet Percentages: Part 2.

So that’s what I mean by ‘adequate protein on a diet’ when I use that phrase.  It’s context dependent with the primary variables being body fat percentage (as this goes up, protein requirements go down), caloric intake (as caloric intake goes down, protein requirements go up and vice versa), and activity (with regular activity generally increasing protein requirements).

I realize that there are no hard and fast rules here, but do you have a figure kicking around that brain of yours that articulates what is the maximum amount of fat loss per week while maintaining a decent  fat/muscle loss ratio once someone has approached single digit body fat? I’m guessing it’s no where near 2 pounds at that point.

I’m at about 9% and I’m regularly hitting a 7,000 calorie deficit (Bodybugg) and I’m starting to see my strength levels go down regularly for the first time. It looks like I’m starting to lose a little muscle too but I’m not skilled enough with the calipers to know for sure. Obviously I need to cut back on the deficit and see how things go but it made this question pop in my head. Hope you can use it on your site sometime. Thanks for all your hard work and great info.

Answer: The short-answer, as always, is that it depends.  Now here’s the long answer.

First, the idea that 2 lbs/week is the maximum amount of weight/fat loss that should be achieved has been around for years but nobody seems to know where it comes from.  Certainly there’s no physiological reason for this to be a maximum and much larger rates of true weight/fat loss can be achieved with extreme deficits.

Anyone who has watched The Biggest Loser knows this to be true and even without that level of asininity, very large folks following a protein-sparing modified fast as per my Rapid Fat Loss Handbook have been measured at 1/2-2/3 pounds of fat loss PER DAY.  Which is 3.5+ pounds of fat per week.  Clearly 2 lbs/week is a bogus value in a physiological sense.

So where did 2 pounds come from?  I suspect it was mostly a behavioral/reality issue.  Assuming a value of 3,500 calories per pound fat loss (and I’d note that this value has some issues inherent to it discussed in The Energy Balance Equation), to lose even 2 pounds per week means a net deficit of 7,000 calories per week or 1,000 calories per day.

Which means either a lot of activity (a minimum of 2 hours for someone relatively untrained) or fairly large-scale caloric restriction.  Now, certainly this can be achieved with extreme diets but my guess is that the practicality of the 2 lb/week rule came out of this idea: for most people, a larger daily deficit isn’t realistic.  At the time it was also assumed that faster weight loss was associated with poorer long-term results but, as discussed in Is Rapid Fat Loss Right For You?,  depending on the specifics, the truth is actually exactly the opposite of that idea.

Of course, weight loss isn’t fat loss and the issue of muscle loss is a concern, I discuss this in detail in What Does Body Composition Mean? as well as elsewhere on the site.  Another issue regarding the 2 pound per week rule is muscle loss while dieting; this is (or at least should be) a concern and, certainly early studies found that bigger deficits caused greater muscle/lean body mass lost.  But there were at least two problems with this:

1. The caloric intake was stupid low.
2. There was no exercise, especially weight training, done.

Number 2 is of course important, while all types of activity will spare some muscle in beginners on a diet, weight training is probably the best overall approach.  And it simply wasn’t a part of mainstream weight loss approaches or research when most of the work was being done.

Even there, number 1 is probably the bigger issue here.  Even very obese individuals need a certain amount of dietary protein to prevent muscle loss and when you only feed someone 300 calories/day, even if 100% of it is protein (and most very low calories aren’t because they are set up stupidly), that’s a maximum of 80 grams of protein.  Which is usually too little.  And is also is why I set up the Rapid Fat Loss Handbook diet by protein intake and not by calories.

You have to meet protein requirements on any diet to limit muscle loss; when researchers started giving obese folks a minimum of 1.5 g/kg lean body mass of protein on a PSMF approach, muscle loss stopped.    For a 300 pound individual with 40% body fat, that’s a daily protein intake of 122 grams per day or a minimum of 500 calories.  With tagalong carbs and fats, total daily caloric intake will be higher. Simply, setting calories at 300/day won’t allow sufficient protein; yet many of the data points came from exactly those studies.

Of course, all of the above really applies mainly to overweight individuals; for what should be obvious reasons obesity researchers tend to not care about fat loss in lean individuals.   However, there was work done on changes in body composition, usually during starvation (and most of this was by Gilbert Forbes who literally spent 30 years writing about the topic) showing that one of the primary predictors of what was gained or lost during over- or under-feeding was initial body fat percentage (discussed in detail in Initial Body Fat and Body Composition Changes).

And, as per that article, as folks get leaner, for reasons discussed in detail in Calorie Partitioning Part 1 and Calorie Partitioning Part 2, muscle loss tends to increase.   Some early work suggested that, when you were lean, you’d lose roughly 1 pound of muscle for every 3 pounds total weight lost.  That is, up to 33% of your total weight loss might be muscle.

And with the idea that faster weight loss made muscle loss worse, suggestions to limit weekly weight loss to one pound per week when you got lean often were made.  Duchaine echoed this in the seminal Bodyopus and for a long time I suggested 1-1.5 lbs/week as the ‘sweet spot’ for weekly weight loss for leaner individuals.  It’s still not a bad value for moderate deficit diets, mind you, and I use that as the sweet-spot value in Adjusting the Diet.

But the 1-1.5 lb/week value isn’t an absolute, some can lose faster than this as lean people using my Rapid Fat Loss Handbook have shown.  True fat losses of 2-3 lbs/week in lean individuals is possible at least for short periods of time (one limitation of the RFL approach for lean people is that it should only be used for about 2 weeks straight before something less extreme is done).

So clearly it is possible to lose more than the stock-standard 1-1.5 lbs/week of true fat without muscle loss.  And understanding why and how means understanding why muscle loss tends to occur on a diet in the first place.

Arguably the biggest reason (and the one we have only limited ability to control) is  shifting hormones: falling leptin and testosterone, increases in cortisol, and a whole bunch of other (bad) stuff happen during dieting and most of these things become more pronounced the leaner you get.   Cyclical diets (like the Ultimate Diet 2.0) and strategies such as The Full Diet Break go a long way towards helping with those issues since the periods of high-caloric intake help to restore hormone levels back towards normal (they can’t ever restore them completely).

Of course, as noted in those articles, a big reason bodybuilders use so many drugs is to fix problems while dieting. With enough testosterone, thyroid meds, thermogenics, anti-cortisol compounds, appetite suppressants, etc. they can basically replace everything that the body isn’t making anymore.

An additional factor is that people’s ability to train intensely often goes down on a diet and maintaining the appropriate tension stimulus to keep muscle is key to avoiding muscle loss.  This is one of the reasons I find the whole idea of increasing volume and frequency of training on a diet half-assed; as discussed in Weight Training for Fat Loss Part 1 and Weight Training for Fat Loss part 2, people do better when they cut volume and frequency and focus on maintaining intensity.

Diets such as the Ultimate Diet 2.0 get around this by having the heaviest workout after carb-loading (so you can go heavy) and even basic cyclical ketogenic diets help with this.  Refeeds refill muscle glycogen and that allows people to go heavier in the weight room; strength isn’t a perfect proxy but if you’re keeping your weights up in the gym, you’re probably not losing muscle.

I actually think that training poorly is part of why guys like Dan Duchaine found that more than 1 lb/week fat loss was too much without props.  Training in the 80′s and even early 90′s while dieting was often done in a rather stupid fashion.  People trained too many days with too much volume and often dropped intensity too much because of it.  That alone allows muscle loss to occur.

Coaches who use lower volume and/or lower frequency but higher intensity training on a diet don’t see that level of muscle loss on a diet (if they see any at all). As noted, people on the Rapid Fat Loss Handbook diet don’t report muscle loss so long as they do the training (low volume/low frequency/high-intensity) in the book.

Excessive amounts of cardio contribute to this as well.  When you have drugs to spare muscle loss, 2-3 hours/day of cardio is fine and lets you eat more.  For naturals, while it’s sometimes necessary to go to 2 hours/day at the end of a diet (to offset a cratering metabolism), too much cardio just causes the muscles to fall off on a diet.  Especially when combined with a big deficit and inadequate protein.  But people did (and still do) nutty shit when they diet to get lean; excessive cardio is part of that.

Adequate protein is also a big issue.  For years I went with the stock standard 1 g/lb but on a diet this is probably insufficient.  As I discuss in detail in The Protein Book, 1.5 g/lb should probably be the minimum while dieting (certainly some people get away with less but this is highly individual).  On extreme approaches, more than that (2 g/lb) may be needed.

So bascially if you look at old-school dieting for lean individuals, it had some major flaws including

1. Often (not always) inadequate protein.
2. Stupid training.
3. No use of refeeds or full diet breaks to reset hormones and allow better training to be done.

And while certainly many make the above work, just as many (if not more) have issues with strength and performance loss.

So what’s the answer to your question after all of that?  Well it depends.  If you insist on doing things badly, training too much, excessive cardio, inadequate protein, too stubborn to use refeeds and diet breaks, the old value of 1 lb/week may be exactly right with 1.5 lbs/week maybe being achievable.

Do things in what I consider the ‘right’ way (proper training, adequate protein, refeeds/full diet breaks used) and you can get faster fat loss per week without performance or muscle loss.  1.5 lbs/week is usually achievable for most and, for short periods, with extreme diets, more than that can be achieved without muscle loss.

Of course, there is still individuality in all of this probably relating to genetics and hormone levels.  Some people lose muscle more than others, they have to go with slower rates of fat loss even if they do everything ‘right’.  And others are lucky, they lose fat more easily (some of the reasons are discussed in The Stubborn Fat Solution).  But they tend not to be in the majority of trainees (they are usually in the majority of folks who get on stage).