Eating Loads of Protein Won't Make You Fat

5.5 Times the RDA With No Added Body Fat

We keep forgetting it, but eating lots and lots of protein won’t do a thing to negatively affect your body fat levels. Here’s why.

Protein: The Magic Macro?

I’ve been working my glutes a lot lately. It does seem to be, after all, the body part of the moment, and not just for women. Besides, I’d been neglecting them for too long. How could it be otherwise since the only time I really see the damn things is when I’m in Macy’s trying on a new pair of chinos and I’m lucky enough to nab the big dressing room with the 3-panel mirrors?

In any event, after a futile month, it struck me: I was still in my summer diet mode. I wasn’t eating enough to grow anything, let alone my wanna-be Instagram-worthy bootie.

You can’t build a house without bricks, right? And neither can you build a more muscular butt or muscular anything without extra protein. You also most likely need to take in calories above and beyond maintenance levels.

I’m embarrassed to say, though, that my thinking was outdated. I’d forgotten what I know to be true and instead fallen back on conventional dietary thinking, which is synopsized like this:

“Eating extra protein during times of carbs and energy sufficiency contributes to increased fat storage, not muscle growth.”

That is, after all, what nearly every dietitian will tell you, what nearly every nutrition textbook will tell you. But it’s hogwash. It’s poppycock. No, no, we need a stronger word to describe this nonsense; we need to combine hogwash and poppycock to get hogcock. That’s what it is.

Moreover, it’s probably that belief that’s to blame for so many people, including me in this instance, failing to make progress in the gym.

By trying to maintain a relatively low level of body fat, I had followed a maintenance or below maintenance number of calories and treated protein like just another macronutrient: one that must be reined in lest fatness ensue.

But the truth is, eating a lot of protein, even up to 5.5 times the recommended daily allowance, will not make you gain any additional fat, even if all that protein adds a ton of calories to your diet. Instead, it seems to have a protective effect against fat during periods of increased energy intake while also leading to additional muscle mass, provided circumstances are right.

230 Grams of Protein with No Lifting Added 7 Pounds of Lean Mass

We’ve known for some time that overfeeding carbohydrates and/or fat results in body comp changes that are different from overfeeding on protein. We’ve also known for some time that dietary protein appears to have a protective effect against fat gain during periods of overeating, but just how protective, we didn’t know.

Enter George Bray and his colleagues in 2012. They randomized subjects to partake in one of three diets: low protein (5%), normal protein (15%), or high protein (25%). Randomized subjects were then “force-fed” 140% of their maintenance calories – about an extra 1,000 calories for 8 weeks straight.

As far as grams of protein per group, that worked out to be around 47 grams for the low protein group; about 140 grams for the normal protein group; and around 230 grams for the high group.

Carbohydrate intake was kept at about 41-42% between the groups, while dietary fat ranged from 33% in the high protein group to 44% and 52% in the normal and low protein groups, respectively.

After doing their dual X-ray absorptiometry (DXA) magic, the scientists found that while all subjects gained approximately the same amount of fat (the high protein group gained a little less than the other two groups), the high protein group gained about 3 kilograms (approximately 6.6 pounds) of lean mass.

I know what you’re thinking: “Hey, all three groups gained the same amount of fat. Where’s this alleged protective effect of protein, Forrest?”

Slow down, Bubba. The participants in the study were not resistance-trained. Neither did they perform any exercise during the study. That extra 6.6 pounds of lean mass fell on them like manna from heaven. Clearly, their results showed that excess protein during an overeating phase contributed to lean body mass gains.

That throws a high-protein pie in the face of all those dietitians who still insist that a calorie is a calorie.

But what would happen if someone took it one step further? What would happen if someone conducted a similar study, but this time with resistance-trained athletes and an even higher protein intake?

5.5 Times the Amount of Protein, This Time with Lifters

Dr. Joey Antonio, a former contributor to T Nation, set about to “determine the effects of a very high protein diet (4.4 g/kg/d) on body composition in resistance-trained men and women.”

The study design was simple: Thirty healthy weightlifting men and women were randomly assigned to a control (CON) group or a high protein (HP) group. The CON group was instructed to maintain their same training and dietary habits over an 8-week period. The HP group was also instructed to maintain their same training and dietary habits (i.e., maintain the same carb and fat intake), albeit with the added instruction to take in 4.4 grams of protein per kilogram of body weight (about 5.5 times the RDA).

The math shows that the HP group would be ingesting around 800 calories per day more than the CON group. These additional calories were all from protein: 307 +/-69 grams of it, compared to a protein intake of 138 +/- 42 grams in the CON group.

Here’s the clincher: After 8 weeks, despite eating about 800 extra calories per day – all of it from protein – the HP group experienced no changes in body weight, fat mass, or fat-free mass.

You probably have mixed feelings about those results. On one hand, you’re probably elated that all those extra calories from protein didn’t result in any additional tubbiness. However, you’re probably disappointed that it didn’t lead to any additional muscle mass.

Read on for a clearer picture.

Some Rationalization

In the first study described above (Bray, et al.), the untrained subjects gained 6.6 pounds of lean mass just by increasing protein intake to about 230 grams per day. No exercise was involved, so this suggests that they weren’t getting enough protein to begin with, which casts dark aspersions on the U.S. recommended daily amount of protein (0.8 grams per kilogram, which would be about 63 grams for a 175-pound person).

That brings us to Antonio’s study: Why did the HP group, despite ingesting about 5.5 times the RDA for protein, fail to gain any lean mass, let alone fat mass? Antonio explained it this way:

“The lack of body composition changes in our group may be attributed to the fact that it’s very difficult for trained subjects to gain lean body mass and body weight in general without significant changes in their training program.”

So, it appears that the HP group simply wasn’t hitting it hard enough. Nowhere in the text does Antonio offer whether the resistance-trained athletes were just average gym goers in maintenance mode or mass-crazy gym rats, but you have to figure it’s the former, given what Antonio speculated later in the text:

“It would be interesting to ascertain if a high protein diet concurrent with a heavy resistance bodybuilding training regimen would affect body composition (i.e., increase lean body mass and lower fat mass).”

Why Won’t Protein Turn into Body Fat?

Admittedly, the title of this subsection is a little misleading. Protein can turn into body fat, but it’s unlikely. Biochemically, turning dietary fat into body fat is, as you might guess, easy-peasy, and turning dietary carbohydrate into body fat isn’t that much more difficult.

Turning protein into body fat, however, is an entirely different type of challenge. It takes several biochemical and hormonal steps and it’s monitored closely by the liver, which metes out amino acids according to the body’s metabolic needs (tissue breakdown, tissue synthesis, catabolism, anabolism, etc.)

As such, you can believe, with a high degree of certainty, that protein, despite what “common sense” might suggest, has a protective effect against fat gain in times of caloric surplus, particularly when combined with weightlifting.

What to Do with This Info

All this might not be news to you, but it’s something that we need to be reminded of, because it’s so contrary to what we used to believe, or what many dietitians currently believe.

Having said that, here’s what I think you should take with you from these studies and this article:

  • Regular, non-training Joes should probably throw the 0.8 grams of protein per kilogram RDA out the window and strive for at least 50% more.
  • For most weight trainers who want to add muscle (but repeatedly fail), you likely need to eat more protein; maybe not 5.5 times the RDA, but maybe more than what you’ve previously believed to be adequate. The added calories will not turn to fat.
  • Lastly, it’s probably impossible to eat that much extra protein from whole food sources, unless you routinely carry around a side of beef in your Yeti ice chest. You must, as the subjects in Antonio’s study did, augment whole-food protein choices with protein powder.


  1. Antonio J et al. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr. 2014 May 12;11:19. PubMed.
  2. Leaf A et al. The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review. Int J Exerc Sci. 2017;10(8):1275-1296. PMC.
  3. Bray GA et al. Effect of protein overfeeding on energy expenditure measured in a metabolic chamber. Am J Clin Nutr. 2015;101(3):496-505. PubMed.

I’ve frequently used the argument that one could put down 1500cals of carbs or fats relatively easily, sometimes in a single meal. But almost no one could manage to eat 1500cals worth of protein in one sitting.

For maths…
12oz chicken breast (raw) = ~106g protein
x4 = 48oz chicken breast = ~424g protein

When in doubt - eat more lean protein!


I think you’re right, but this extends as well to most highly processed foods. It’s easy to go to a fast-casual restaurant and wolf down 1000 calories before your meal is even served (soda, bloomin’ onion, bread and butter). But, no one does this with real foods, even without protein. Do you know anyone that has ever said “Man, I really wish I didn’t eat all those bananas last night. I can’t believe I ate 16 of them!”. It’s not uncommon, though, for someone to eat an equivalent amount of calories in the form of Goldfish crackers or other processed food in a box.

Not that anyone asked, but my strategy is allow myself as much real food as I want. Plain, full fat yogurt. Raw almonds. Salmon, chicken, steak. Blueberries, apples, strawberries. But avoid highly adultered foods (nonfat dairy, “nutrition” bars, etc, crackers, etc…). Not that I’m 100% compliant, but this is my goal.


Great article. I only read the Bray abstract, so this is admittedly an ignorant question, but help me with the math:

On the same caloric intake, the high-protein group gained the same fat weight PLUS 3kg of lean weight?

The conclusion appears to point to endpoints around energy expenditure, so maybe it wasn’t powered to look at the above and physics can still exist, but that brings me to my second question:

How can we conclude my energy expenditure increased with protein if I gained more total body weight?

I’m not being purposefully challenging, because your conclusion is not nearly as declarative (nor do I find it controversial, based on what you presented), but I can’t wrap my head around that source article (again, I only saw the abstract, so I’ve got ~10% of the picture)

They gained a bit less fat, and 6 POUNDS not kilos ahah. The subject were not resistance-trained. We can assume that they had a subpar diet as well. I’m guessing they weren’t getting enough proteins to begin with, like most people, and their body comp improved to “baseline human levels”. No resistance training doesn’t mean no activity.

Protein is annoying to storage, compared to fat (95% of adipose tissue comes from fat). They all had the same calories, but others had more carbs and fat to storage. Meaning that the body had “less” available energy. I’m guessing they also felt healthier and moved more, and since they had more lean tissue all of that contributed… Calories can be complicated ahahah

Okay, now I’m doubling my proteins hehe

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Whoops! Edited!

It’s presented as if they gained statistically equivalent fat, or at least similar, and a greater delta of FFM.

I understand this is the hypothesized mechanism, but the math, as I read it, doesn’t hold up. I can’t gain more total weight on the same calories, yet have an increased energy expenditure. If they had eaten the same calories from fat and carbs, and then added protein (as in the second source), I’d buy this.

What I’m thinking now, after reading our response and my own typo, is it’s most likely there was no statistical variance in any measure absent, potentially, the FFM. That would allow us to gain more fat and more total weight within numeric differences, call it equivalent, and leave room for the FFM gain.

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Okay so I read the whole thing. Indeed they gained the same amount of fat, but the higher protein diets induced not only an increase in fat free mass, but also in expenditure.

And it started at day 1 for energy expenditure! Krebs theorized that protein increased energy expenditure through urea synthesis, and protein synthesis. Some tissues and organs are stimulated a lot (kidneys, liver, skin, muscles) and their rate of energy utilization altered.

After 8 weeks, the energy expenditure of skeletal mass and residual mass was lower for the low protein diet, but significantly higher for the other (-10 for the low protein, + 175 for the high protein).

We can guess that all this protein triggered many reactions to create this muscle, utilizing lots of energy. We’ve all seen how untrained individual gain fast. I’m persuaded the average human right now is in a terrible, subpar physical state. The body knows it. It wants to come back to its original state.

Also, it has been theorized that protein takes more energy to be processed, 20-30% of its own energy, compared to 10-20% from carbs, and 0-5% from fat.

Anyway, indded, it’s hard to wrap our mind around this. How can you spend more energy and gain more weight? The answer is probably that they were overfed at 140% of their baseline. It’s like, when you come back from an injury, or begin the gym: you gain muscle and lose fat at the same time. I’m guessing that in a overfed state, the body doesn’t utilize everything it ingests.

It certainly holds true for protein: hence why it’s better to have more frequent meals to optimize protein synthesis. Our lame body can’t or won’t storage it


Where did you find the full article?

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You’re a better man than most of us, Gunga Din!

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Yeah, I know, it’s weird. The group was probably deficient in protein intake in the first place, so the added protein manna from heaven was sucked up by lean body tissue.


In the references, it’s the third study. Click on the link next to the DOI, just before the Abstract

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Ok, after reading the confidence intervals, I can now accept everything. Arithmetic simply won’t allow me to believe increased energy expenditure resulted in a higher total body weight (which requires increased storage). The individual results, however, can still tell a trending story that overeating protein has a different impact. There is no statistical significance in any group (outside that they still had skeletons), so I’m good to take this as a hypothesis based on numeric trends.

Thanks @TC_Luoma and @aldebaran!

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Excellent piece. I’d add that this research also debunks two other common myths. First, “the body doesn’t store protein.” This might be more correctly stated as “the body doesn’t store protein as fat,” because we have a word for stored protein–it’s “MUSCLE.”

Second, there’s the myth that is common among keto “experts” that excess protein is turned into glucose via gluconeogenesis. The theory is that the body converts “extra” protein into glucose when confronted with a surplus. In fact, the opposite is the case: the body resorts to gluconeogenesis only when glucose is needed and in the absence of other sources, turning either to dietary protein or through catabolic processes that result in muscle loss. In support of this, see: The Ketogenic Diet for Health: If You Eat Excess Protein, Does It Turn Into Excess Glucose?

In any event, I’ll keep pouring on the protein and enjoying the thermic benefits of high consumption, also!

When the study-flingers argue against the idea that it’s nearly impossible to gain fat from lots of protein, I give them The Chicken Breast Challenge:

Get fat on baked, skinless chicken breasts. That’s it.

While possible on paper, I’ve never seen anyone do it, unless of course their chicken is smothered in ranch dressing and cheese and they forget to mention that part. I discussed this with Will Brink too and he agrees: while it seems possible if someone were really really motivated to take the challenge and prove me wrong, it just doesn’t happen out here in real life.


I imagine calling this “The Rabbit Starvation Challenge” didn’t fare well with marketing, haha.

Excellent points. Thanks!

Your maths remind me: Someone needs to collect study data on that guy in Philly who ate an entire rotisserie chicken for 40 days straight. Was anyone tracking his gainz? lol.


About 162 grams of protein in an entire chicken. What a noob.



I was thinking this when i heard it was only 1 chicken per day

Like that’s basically a large meal for me and my fat ass.

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