Excess Protein and Fat Storage – Q&A
Question: I have done a lot of study in diets and nutrition but to this day I have not been able to get any concrete evidence on what happens with excess protein in the body and I’m hoping you can help.
To make things simple, lets take a theoretical diet consisting of 5000 calories of pure protein for a 60kg, 175cm female.
Many people claim that excess protein will get wasted while others say that all excess calories eventually end up being stored as fat.
I have done my own research on the breakdown of protein into amino acids and I understood it as: some of the amino acids are wasted while others will go through the cycle of conversion and will still be used by the body for energy.
Answer: Ok, first things first. The example given above is absurdly non-physiological. The satiating power of protein would make such a high protein consumption impossible. That is, 5000 calories of pure protein is 1250 grams of pure protein. Can’t be done. Beyond that, while the biochemical pathways for the conversion of protein to fat do exist in humans, the likelihood of it ever happening in any but the most absurdly non-physiological circumstances are effectively nil.
Let me put this in perspective. Despite a lot of claims to the contrary, the actual conversion of carbohydrate to fat in humans under normal dietary conditions is small approaching insignificant (a topic I discussed at least briefly in Nutrient Intake, Nutrient Storage and Nutrient Oxidation).
Make no mistake, the conversion of carbs to fat (a process called de-novo lipogenesis or DNL) can happen but the requirements for it to happen significantly are fairly rare in humans under most conditions (to discuss this in detail would require a full article, interested readers can search Medline for work by Hellerstein or Acheson on the topic).
At least one of those is when daily carbohydrate intake is just massive, fulfilling over 100% of the daily maintenance energy requirements. And only then when muscle glycogen is full. For an average sized male you’re looking at 700-900 grams of carbohydrate daily for multiple days running.
Which means that the odds of protein being converted to fat in any quantitatively meaningful fashion is simply not going to happen. Certain amino acids are processed to a great degree in the liver (as I discuss in The Protein Book) and this can produce glucose, ketones and a few other things. But triglycerides (the storage form of ‘fat’) isn’t one of them.
I imagine that if protein were going to be converted to fat, it would first have to be converted to glucose and only if the amount produced were then in excess of daily maintenance requirements would there be conversion to fat. But as noted above, this simply isn’t going to happen under any even reasonably normal circumstances. No human could eat enough protein on a daily basis for it to occur.
What will happen, as discussed in Nutrient Intake, Nutrient Storage and Nutrient Oxidation. is that amino acid oxidation (burning for energy) will go up somewhat although, as discussed in that article, it’s a slow process and isn’t complete.
So, as noted above, while the pathway exists for protein to be stored as fat, and folks will continue to claim that ‘excess protein just turns to fat’, it’s really just not going to happen under any sort of real-world situation. Certainly we can dream up odd theoretical situations where it might but those won’t apply to 99.9% of real-world situations.
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Interesting.
But you will still gain fat some way even if you get your calories from protein!?? Is it just that the body then stores almost all of the carbs and fat instead? F. example i your have a protein/carbs/fat ratio og 80/5/15, will still none of the 80 % of calories coming from protein be stored as fat?
Read the Nutrient Intake, Oxidation and Storage Article. Of course you can still get fat from excess anything, it’s simply not through conversion of protein (or usually carbs) to fat.
I don’t understand, at least with respect to carbohydrate conversion. So if theoretically I eliminate almost all the fat from my diet, then I can eat a non-trivial (read: reasonable) caloric surplus based on protein and carbs and gain very little or no fat, simply because of the “requirements for it [conversion] to happen significantly are fairly rare”? So are very low fat diets the key after all? Please advise, thanks.
I linked to this article in today’s piece for a reason. Or look at the comment immediately above yours since I told him the exact same thing.
http://www.bodyrecomposition.com/nutrition/nutrient-intake-nutrient-storage-and-nutrient-oxidation.html
I’ll take that as a yes. An almost all carb, all protein diet would rarely lead to fat gain, but would not lead to fat loss either, as the body’s ability to oxidize a given macro is determined by its storage capacity and level of intake. My initial incredulity stemmed from the old wives’ tale that excess carbs leads to fat gain, which is why the even older old wives’ tale of low fat programs are held in such low esteem these days.
Incidentally, a definitive statement from a purported expert would help better than any uneducated inference I could possibly make.
Lyle, your article is kinda broken. An error message pops up.
Anyway, Google still had the article in its cache.
I can’t really find an answer to Deo’s question there. So what is it?
A maintaining/bulking diet that consists of nearly no fat will help you have leaner gains?
How come this form of died is so extremely outdated?
You guys need to read more carefully. Lyle never said there was any advantage to high carb/low fat diets for weight loss. If you’d read practically any of Lyle’s fat loss articles on this site I would think it’d be obvious that it’s not his opinion on the topic.
You’re reading things into the article(s) that aren’t there. I’m not trying to flame anyone here just trying to make a point/suggestion that you reread these articles more carefully.
Here’s a relevant quote from the article Lyle linked.
“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.”
Bingo. A mistake in almost anything I write is inferring. If I want to say X, I’ll say X. I won’t say X and mean Y. There’s also a reason I tend to link to related articles when I write these things. If you are going to take a single article of mine and read a bunch of stuff I didn’t say into it, you’re going to draw some very silly conclusions. And taking this singular answer to a singular question and reading something like you’re reading into it is a huge mistake. The other 200 + articles on the site clearly show why that’s not what I’m saying in any way or form. Go read them.
Overkill,
I understand what you’re trying to say, and I’m not taking what you say as flame, but you should understand things from my point of view. I was quite upfront about “reading things into” Lyle’s article that could very well be wrong, which is why I asked for clarification. And I wasn’t asking about fat loss, but about fat gain, since the question I had was about the body’s general inability (or very poor ability) to convert carbs and protein into fat. Anyways, this is the last time I’m bringing it up. I’d hate looking like a troll.
But Lyle (I don’t expect you to publish this), it’s not quite as complicated as you’re making it out to be. I just did a very simple exercise in deductive reasoning. If all men are mortal, and Socrates is a man, then Socrates can die. So I’m just taking what you’ve written to mean that if the body finds it extraordinarily (almost impossible) to convert protein into fat, and it is nearly as difficult for the body to convert carbs into fat, then a fat-free diet should not lead to fat gain, or very little, even on a caloric surplus of carbs and protein, assuming, as you wrote, we’re talking about most reasonable circumstances.
If this inference is incorrect, you could tell me why instead of citing other articles you’ve written, which actually don’t do the job of enlightening me as you think they should. Maybe you don’t want to think of this website as a medium for teacher-student relationships, but I think of you as a very positive influence on the bodybuilding/athlete community and thus, in some ways, a teacher….someone who takes the time to clear up people’s confusions.
The part I quoted works both ways, Deo.
If you’re eating a surplus high in carbs and protein, it just means that less and less fat will be oxidized and every bit taken in will be stored to create a net fat storage. Even if you consume no fat, which isn’t at all practical, once glycogen levels are full the excess carbs beyond what is needed for energy will be turned into triglycerides and stored as fat (at a slightly higher TEF, I believe – but insignificant in the big picture).
But this is all rare because most diets are not that void of fat and in that big of a surplus.
Ok I think I get it. I just assumed that even above a caloric surplus, it would be hard for the body to convert protein/carbs due to the physiological difficulty of the “biochemical pathways” doing it (so that any excess would be disposed of in one’s waste, and not stored as fat), but I reread the line about glycogen levels being maxed out, which answers my question. Thanks everyone.
I think Deo question is valid.
The article, and also the linked one, made me wonder the same thing….
Hi Lyle,
I just want to say a big thanks to you for posting my question and your highly valued reply as this has caused some big debates in the past.
I’ve begun to think of diets as similar to flex fuel systems in cars. You can either burn carbs for fuel or fat, but you won’t burn both at the same time. You have to flip a switch and choose which fuel you will use. By sticking to low carbs you’ve flipped that switch to “fat” and your body will burn fat. Just an observation! Oh, and that means that foods that are high in both carbs and fats are like a wicked cocktail that kill any attempt at losing weight – much less losing fat.
Hey Lyle, hey Overkill.
I think it’s terrible how you respond to the questions.
I pointed out that I read (I actually read the article before) the linked article.
Then you complained about people interpreting too much into the article, which is quite ironic. Because the article you posted did not answer the question directly. If at all it answered the question by interpreting something into it.
I like how Overkill tried answering it. Yet, I dont think the point you’re making is valid.
Let’s talk about bulking up and a surplus of 600 cal/day. If you’d limit the fat to the absolute minimum it should still be less than the surplus.
So could this be a possible approach to lean gaining? I know it’s unpractical.
You would need to be eating less than 600 kcal of fat in theory or all of the surplus could be stored as fat just from the fat intake. No conversion would be needed.
Ive got a question.
Say someone can maintain at 3000kcals and lets just say all of their needs are met with a 33.3/33.3/33.3 diet, or 250g protein, 250g carbs, 111g fat.
Now say I keep everything the same, but double the protein to 500g, making the total calories 4000kcals (a +1000kcal surplus)
Since fat is not being cut below needs, does this 1000kcals of protein automatically get stored as protein. Or used as fuel? Theoretically this change in diet would yield a 2lb lean mass gain per week.
Furthermore, one could also increase carbs to 500g per day, to increase the surplus by another 1000kcals, making the muscle gain 4lbs per week.
Im not really understanding the reasoning here. Isn’t fat the bodies main fuel source? And if you are taking in 1000kcals a day of fat, isn’t that amount of calories easily met by your RMR and light activities?
So in theory, this would mean that the individual would HAVE to gain 4lbs of stored protein/carbs (ie muscle) per week, OR this excess energy would have to be burned. And if it is burned, then this means you are shifting your bodies preference for protein/carb usage instead of fat at low intensities. If this is the case, then its a horrible idea, as the initial muscle gains would be followed by a lifetime of living off of your muscles energy. Otherwise, the 4lb gain of lean mass per week would be pretty sweet.
Its not black and white. The body is smart. It adapts. Eat more protein and it will adapt by focusing more effort at taking care of protein (store+burn). The same goes for carbs (store+burn). Fat oxidation will not adapt to increases or decreases in fat intake by the same amount, but it will adapt to changes in protein and carb intake. However it will never shut down oxidation completely. Some tissues still prefer fat as fuel, while other tissues are less picky.
How much protein you store as muscle tissue are limited by how primed the body is for building new muscle (hormone levels, energy surplus, gene transcription, etc.) and available substrates. Organs in the gut will also hypertrophy as you increase protein consuption. Protein oxidation will increase to match intake, although slowly. Adaptation is aimed at finding homeostasis any way it can. Dont dream of gains that cannot be reached (yes, I know you speculate).
Change in amount of stored fat is described by the equation: fat intake – fat oxidation = x. In the unlikely event of DNL, more fat is added. So, enjoy your carb refeeds (provided you have depleted yourself, of course). Fat free diets are unhealthy and not very practical. Enjoy a moderate amount of fat in your diet.
End rant. (I hope Lyle corrects me if there is some mistakes in my post)
I know its not black and white, and my example is definately extreme. But it makes sense to me that if you take in an extra 500 calories of protein over maintanence, then you are going to add fat. It might not be that the protein is converted to fat, as this article suggests, but maybe some of that protein is used for energy. In this case, less fat will be used for energy, and thus there will be a surplus of fat.
So maybe excess protein doesn’t get CONVERTED to fat, but excess protein would still lead to and increase in fat storage.
So doesn’t it really still just come down to calorie balance?
KISS:
1. A diet of purely protein, above or below maintanence, will kill you.
2. A diet without fat is one of the few times where the body starts converting carbs into fat. Above or below maintanence.
1. A diet of pure protein is pretty much impossible to achieve in practice. All proteins have some tagalong carbs or fats.
2. You’re not going to get net lipogenesis (fat production) below maintenance calories.