• Protein Doesn't Make You Fat



      by Dylan Klein T-Nation

      Here's what you need to know...

      While it's biochemically possible for protein to turn into fat by ingesting extremely high numbers of calories or extremely large amounts of protein, it's unlikely you'll ever be in that situation.

      You can pretty much eat as much protein as you want and it won't turn to fat.

      That old chestnut about only being able to absorb 30 grams of protein in one sitting is bunk.

      Aside from building muscle, protein provides essential amino acids that serve as the building blocks for other proteins, enzymes, and hormones within the body that are vital for normal functioning. Without this steady supply of amino acids, the body resorts to breaking down its own proteins typically from muscle in order to meet this demand.

      Protein has its share of misconceptions. It's not uncommon to hear claims that dietary protein eaten in excess of some arbitrary number will be stored as body fat. Even those who are supposed to be reputable sources for nutrition information propagate this untenable dogma. While paging through a nutrition textbook I came across a section in the protein chapter regarding amino acids and energy metabolism (1). To quote the book directly:

      "Eating extra protein during times of glucose and energy sufficiency generally contributes to more fat storage, not muscle growth. This is because, during times of glucose and energy excess, your body redirects the flow of amino acids away from gluconeogenesis and ATP-producing pathways and instead converts them to lipids. The resulting lipids can subsequently be stored as body fat for later use."

      This is, more or less, supported by another textbook I own (2):

      "In times of excess energy and protein intakes coupled with adequate carbohydrate intake, the carbon skeleton of amino acids may be used to synthesize fatty acids."

      While these passages do take into account the metabolic state of the person, I still find these explanations to be lacking. Indeed, more recent evidence is needed when talking about amino acid conversion to fatty acids. While the metabolic pathways to convert amino acids to fatty acids do in fact exist in the human body, the fact of the matter is that under almost no circumstance will this ever happen.

      Protein Digestion Begins in the Stomach and Ends in the Small Intestine

      While the physical breakdown of proteins does take place in the mouth, it's not until the protein reaches the stomach that any appreciable chemical breakdown occurs. This breakdown is facilitated by hydrochloric acid (HCl) and the enzyme pepsin (converted from its inactive form, pepsinogen). Once the initial protein denaturing and peptide cleaving is complete, the product polypeptides pass through the pyloric sphincter of the stomach and into the proximal small intestine (i.e., duodenum).

      The proximal small intestine is where most of the digestion of proteins and virtually all of the absorption of amino acids occurs (~90% is absorbed with a very small amount excreted in the feces). Here even more digestive enzymes are present to break down the remaining polypeptides into their individual amino acids along with some trace amounts of di- and tri-peptides. Once broken down completely, the free amino acids and di-/tri-peptides can then enter the cells of the small intestine where some (like glutamine) are used for energy within the intestinal cells, while the remaining pass through into circulation and head for the liver.

      Protein Absorption Claims

      Before we head on over to the liver and discuss amino acid metabolism with regards to the initial claims, I'd first like to touch upon another related claim that you may have heard in the lay media or from your local gym guru. It usually reads:

      "The average person can only absorb 30 grams of protein at one sitting. Anything above that will be stored as fat."

      Unlike the previous claims, this one offers no context whatsoever. Moreover, it's downright moronic. While this claim looks like a straw man argument readily poised for the takedown, it actually comes from an online article written by a Registered Dietitian.

      Protein Absorption Claims

      Let's, for example, take someone who eats 40 grams of protein in one sitting. If we're to assume only 30 grams can be absorbed at a time, then it's safe to say that the extra 10 grams will be excreted in the feces. If this were the case, most people would be egesting tiny sirloin steaks on a daily basis. Moreover, based on the initial argument, how are you supposed to convert and store 10 grams of excess dietary protein as body fat if you can't even absorb it in the first place? Nevertheless, while I agree that most processes in the human body don't proceed with 100% efficiency, excreting 25% of one's ingested protein content is far from the 90% efficiency supported in the literature (3).

      Theoretically, it could be possible for intestinal absorption of amino acids to be drastically impaired, resulting in excess amino acids passing through into the colon. In reality, this process does occur but only to an extremely limited extent. More severe malabsorption would require the absorptive capacity of the small intestine to be greatly surpassed.

      However, in the face of larger protein and caloric boluses, the stomach just reduces its rate of gastric emptying in order to more slowly supply the gut with incoming amino acids (larger meals take longer to digest). Moreover, the gut itself will slow motility as to increase the time nutrients are available to be absorbed (4).

      The bottom line is that the stomach will take its sweet time to release amino acids into the gut where they can be further detained and subsequently absorbed into the body/circulation. Without this tightly orchestrated process, we as a species would have died off long ago. Having to consume intricately planned out 30g protein meals, multiple times per day in order to effectively derive the nutrients from our food just wouldn't have cut it.

      Liver, the Primary Site for Amino Acid Metabolism

      Let's circle back to the initial claims that excess protein, during times of adequate energy and carbohydrate intake, is converted to fatty acids and stored as body fat.

      The amino acids absorbed and released from the small intestine are destined for the liver. Over half of all the amino acids ingested (in the form of protein) are bound for and taken up by the liver. The liver acts almost as a monitor for absorbed amino acids and adjusts their metabolism (breakdown, synthesis, catabolism, anabolism, etc.) according to the body's metabolic state and needs (2).

      It's here the initial claim comes into play. While the pathways for fatty acid synthesis from amino acids do exist no argument there the statement that all excess protein, under specified conditions, will be stored as fat ignores recent evidence.

      Enter One of the Most Tightly Controlled Studies of our Time

      In 2012, George Bray and colleagues (5) sought to examine whether the level of dietary protein affected body composition, weight gain, and/or energy expenditure in subjects randomized to one of three hypercaloric diets: low protein (5%), normal protein (15%), or high protein (25%).

      Once randomized, subjects were admitted to a metabolic ward and were force fed 140% (+1,000kcals/day) of their maintenance calorie needs for 8 weeks straight. Protein intakes averaged ~47g (0.68g/kg) for the low protein group and 140g (1.79g/kg) and 230g (3.0g/kg) for the normal and high protein groups, respectively.

      Carbohydrate was kept constant between the groups (41-42%), with dietary fat ranging from 33% in the high protein group to 44% and 52% in the normal and low protein groups, respectively. Lastly, during the course of the 8-week overfeeding period, subjects' body composition was measured bi-weekly using dual x-ray absorptiometry (DXA, the "gold standard" for measuring body composition).

      Results

      At the end of the study, all subjects gained weight with near identical increases in body fat between the three groups. (In actuality, the higher protein groups actually gained slightly less body fat than the lower protein group. This, however, wasn't significant). The group eating the low protein diet gained the least amount of weight (3.16 kg) with the normal and high protein groups gaining about twice as much weight (6.05 and 6.51 kg, respectively).

      As you can see, the additional ~3 kg of body weight gained in the higher protein groups (15% and 25%) was shown to be due to an increase in lean body mass and not body fat. To quote the conclusions of the authors:

      "Calories alone contributed to the increase in body fat. In contrast, protein contributed to changes in lean body mass, but not to the increase in body fat."

      While we can't say for sure the exact composition of the lean mass that was gained, we can assuredly say that the extra protein was not primarily used for fat storage. My hunch is that the protein was converted to glucose (via gluconeogenesis) and stored subsequently as glycogen along with some accompanying water weight. Either way, it wasn't body fat.

      Regroup

      Let's take a second for this to sink in. These subjects were literally forced to eat ~1,000kcals more than what they needed to maintain their body weight for 8 full weeks, and even then it was seen that the protein contributed to increases in lean body mass rather than body fat.

      Given the initial claim that once energy, glucose and protein requirements are met, all excess amino acids will get converted to fatty acids and stored as body fat it's clear that those in the higher protein groups didn't succumb to any of those dire predictions. In reality, compared to the lower protein group, they gained very little (if any) additional body fat. This is in stark contrast to what is thought.

      In the end, however, we're still left with the quintessential question underlying the whole concept: what's the maximal amount of protein (amino acids) that the body can effectively utilize before being converted to fatty acids and stored as body fat?

      Given the results of this study, it appears that this number is either way higher than three times the current RDA with concomitant hypercaloric intakes for weeks on end, or, it requires a similar overfeeding protocol drawn out over a longer time period at which point lean mass gains would plateau and fat mass would accrue.

      Either way, both situations are highly unlikely for the general public and even those consciously trying to gain weight with higher intakes of protein and calories. Moreover, this upper extreme is likely to be highly individual and contingent upon other factors such as genetics, lifestyle, training status, etc. Unfortunately, we just don't have the answers to these questions right now.

      Final Thoughts

      So, while we do biochemically possess the pathways needed to convert amino acids to fatty acids, the chances of that ever happening to a significant degree during slightly higher protein intakes, even in the face of adequate energy and carbohydrates, are irrelevant given what we know about the extreme measures that need to be surpassed in order for any appreciable fat gain from protein to take place.

      Indeed, overeating by ~1,000kcals/day for 8 weeks in combination with higher protein intakes didn't amount to any additional gains in body fat compared to a lower protein, hypercaloric diet. Rather, excess protein in the face of overfeeding actually contributed to gains in lean body mass. Quite the contrary to what textbooks and gurus might preach.

      In reality, the chances that excess protein contributes to body fat stores are insignificant, and arguably physically impossible under normal or even slightly hypercaloric conditions that most athletes face on a daily basis. Only until theoretical extremes either for protein intakes or calories or both are achieved will there be any significant contributions to body fat from excess protein intake.

      References

      1. McGuire M, Beerman, KA.: Nutritional Sciences: From Fundamentals to Food. 2nd edn. Belmont, CA.: Wadsworth Cengage Learning; 2011.

      2. Gropper S, Smith, JL., Groff, JL.: Advanced Nutrition and Human Metabolism. 5th edn. Belmont, CA.: Wadsworth Cengage Learning; 2009.

      3. Ten Have GA, Engelen MP, Luiking YC, Deutz NE: Absorption kinetics of amino acids, peptides, and intact proteins. Int J Sport Nutr Exerc Metab 2007, 17 Suppl:S23-36.

      4. Maljaars PW, Peters HP, Mela DJ, Masclee AA: Ileal brake: a sensible food target for appetite control. A review. Physiol Behav 2008, 95:271-281.

      5. Bray GA, Smith SR, de Jonge L, Xie H, Rood J, Martin CK, Most M, Brock C, Mancuso S, Redman LM: Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA 2012, 307:47-55.

      Source: http://www.t-nation.com/diet-fat-los...t-make-you-fat
      Comments 14 Comments
      1. fueledpassion's Avatar
        fueledpassion -
        Well, I've been talked down to for a few years now every time I tried to tell anyone that certain macros have certain fates. Yet, all I ever heard was "calories in, calories out" from this board. For the guys that think their degrees give them credibility - take a good look at the study above...

        For what is it is worth, protein is the least efficient at being stored as body fat, carbs being in the middle and dietary fats being the most efficient at being stored as body fat. The group with the best results happened to be the one with the highest protein intake and the lowest fat intake. This shouldn't surprise us as the metabolic efficiencies of these three macros is a well known subject.

        Consequently, the gain the most muscle mass you'll need a high protein intake for its muscle-building properties as proven in this study, high carb intake for it anabolic insulin properties to shuttle the amino acids and glucose to the muscle, and a low fat intake the ensure that no food (or very little) food is going to the fat cells for storage.

        Contrary to popular belief, if you eat a "square" meal consisting of high protein and fiber content with your starchy carbs, the insulin release won't be as dramatic and thus will avoid putting calories up as fat.

        On the other hand, its almost impossible to convince anyone on this board to consider a low fat diet, such as 10-20% fat intake with a 50/30 split between carbs and protein...
      1. MANotaur's Avatar
        MANotaur -
        Originally Posted by fueledpassion View Post
        Well, I've been talked down to for a few years now every time I tried to tell anyone that certain macros have certain fates. Yet, all I ever heard was "calories in, calories out" from this board. For the guys that think their degrees give them credibility - take a good look at the study above...

        For what is it is worth, protein is the least efficient at being stored as body fat, carbs being in the middle and dietary fats being the most efficient at being stored as body fat. The group with the best results happened to be the one with the highest protein intake and the lowest fat intake. This shouldn't surprise us as the metabolic efficiencies of these three macros is a well known subject.

        Consequently, the gain the most muscle mass you'll need a high protein intake for its muscle-building properties as proven in this study, high carb intake for it anabolic insulin properties to shuttle the amino acids and glucose to the muscle, and a low fat intake the ensure that no food (or very little) food is going to the fat cells for storage.

        Contrary to popular belief, if you eat a "square" meal consisting of high protein and fiber content with your starchy carbs, the insulin release won't be as dramatic and thus will avoid putting calories up as fat.

        On the other hand, its almost impossible to convince anyone on this board to consider a low fat diet, such as 10-20% fat intake with a 50/30 split between carbs and protein...
        Doesnt it have more to do with what you eat the fats with? which is why keto diets work so well to burn fat-

        Im honestly asking not trying to flame, because my logic goes like this-

        you can eat protein and fats, protein and carbs, but not carbs (starchy) and fats.

        I know that you need all three to be "balanced" but in the absence of carbs-and therefore a large insulin spike, wouldnt fat then be fractured and used by the brain and body as energy?

        Also-isnt fiber ultimately digested and absorbed as a fat and not a carb? which is why its not counted in total carb intake?
      1. mcc23's Avatar
        mcc23 -
        I assume that a moderate fat intake + moderate carb intake + "high" protein intake in a moderate caloric surplus would provide the best lbm gains whilst gaining the least amount of fat. . We know that sufficient dietary fats A. Slow absorption of meals (good for insulin) B. Support healthy hormone levels.. This is how I do it, but to each his own.
      1. fueledpassion's Avatar
        fueledpassion -
        Originally Posted by MANotaur View Post
        Doesnt it have more to do with what you eat the fats with? which is why keto diets work so well to burn fat-

        Im honestly asking not trying to flame, because my logic goes like this-

        you can eat protein and fats, protein and carbs, but not carbs (starchy) and fats.

        I know that you need all three to be "balanced" but in the absence of carbs-and therefore a large insulin spike, wouldnt fat then be fractured and used by the brain and body as energy?
        Also-isnt fiber ultimately digested and absorbed as a fat and not a carb? which is why its not counted in total carb intake?
        From my experience, yes to the bold.

        To the red - Yes, if you cut enough carbs out, you'll even go Keto which is a bit more efficient that just breaking down fatty acids. The problem I personally have w/ keto and fat heavy diets is really two reasons. 1) is because fats do a poor job @ offering anaerobic performance. My strength, stamina and recovery won't be the same without glycogen-saturated muscles and 2) even though ketone bodies are released due to carbless diets, a fairly high amount of amino acids all gets burned up as energy in the process called gluconeogenesis because amino acids are located in the muscle cell and can be converted quickly enough into glucose to be used during anaerobic training.

        So basically in a high fat/high protein diet your protein is used as energy to maintain your BMR, while in a high carb/high protein diet, protein is utilized in growth. Keto is effective and appropriate for those who are looking to lose serious weight and do not particularly care if they also eat away 30lbs of muscle in the process. However, for serious bodybuilders, I do not believe Keto has an appropriate place. And low carb dieting just before a show should only be limited to 3-4 weeks, with anabolic help, in order to avoid muscle-wasting.

        I don't know about the fiber. I was under the impression that the body consumes as much energy processing the fiber as the calories that the fiber offers in the first place. For example, some leafy greens that have 10g fiber in them but only have 50 calories is likely to be a stalemate in net calories.
      1. fueledpassion's Avatar
        fueledpassion -
        Originally Posted by mcc23 View Post
        I assume that a moderate fat intake + moderate carb intake + "high" protein intake in a moderate caloric surplus would provide the best lbm gains whilst gaining the least amount of fat. . We know that sufficient dietary fats A. Slow absorption of meals (good for insulin) B. Support healthy hormone levels.. This is how I do it, but to each his own.
        I have found that 40/40/20 is the gold standard, as Arnold always suggested.
      1. MANotaur's Avatar
        MANotaur -
        Originally Posted by fueledpassion View Post
        From my experience, yes to the bold.

        To the red - Yes, if you cut enough carbs out, you'll even go Keto which is a bit more efficient that just breaking down fatty acids. The problem I personally have w/ keto and fat heavy diets is really two reasons. 1) is because fats do a poor job @ offering anaerobic performance. My strength, stamina and recovery won't be the same without glycogen-saturated muscles and 2) even though ketone bodies are released due to carbless diets, a fairly high amount of amino acids all gets burned up as energy in the process called gluconeogenesis because amino acids are located in the muscle cell and can be converted quickly enough into glucose to be used during anaerobic training.

        So basically in a high fat/high protein diet your protein is used as energy to maintain your BMR, while in a high carb/high protein diet, protein is utilized in growth. Keto is effective and appropriate for those who are looking to lose serious weight and do not particularly care if they also eat away 30lbs of muscle in the process. However, for serious bodybuilders, I do not believe Keto has an appropriate place. And low carb dieting just before a show should only be limited to 3-4 weeks, with anabolic help, in order to avoid muscle-wasting.

        I don't know about the fiber. I was under the impression that the body consumes as much energy processing the fiber as the calories that the fiber offers in the first place. For example, some leafy greens that have 10g fiber in them but only have 50 calories is likely to be a stalemate in net calories.
        thats some good insight-Ive got a pretty good handle on biochemistry and dietary dynamics and basics but my knowledge is still pretty lacking. Which is why I typically don't give nutritional/dieting advice.

        My diet is very protein/fat rich. All my meat is tuna/salmon (that I caught and prepared) venison (that I killed)/bison/free range beef (i know its free range cause i get it from my uncle) and fowl of any variety. That is almost always grilled or pan fried in coconut oil. Then after I have eaten my very generous serving of protein i fill in the cracks with veggies. The only time I will add any starch/carb sources is immediately to maybe 2-3 hours post workout.

        Im probably doing this way wrong but it seems to be working for me and I tend to stay pretty lean year round if I stick to it and dont slack off
      1. fueledpassion's Avatar
        fueledpassion -
        Originally Posted by MANotaur View Post
        thats some good insight-Ive got a pretty good handle on biochemistry and dietary dynamics and basics but my knowledge is still pretty lacking. Which is why I typically don't give nutritional/dieting advice.

        My diet is very protein/fat rich. All my meat is tuna/salmon (that I caught and prepared) venison (that I killed)/bison/free range beef (i know its free range cause i get it from my uncle) and fowl of any variety. That is almost always grilled or pan fried in coconut oil. Then after I have eaten my very generous serving of protein i fill in the cracks with veggies. The only time I will add any starch/carb sources is immediately to maybe 2-3 hours post workout.

        Im probably doing this way wrong but it seems to be working for me and I tend to stay pretty lean year round if I stick to it and dont slack off
        There is no doubt that it works to get you lean and keep you lean. I just find that with my fast metabolism it isn't ideal for bulking, especially in my case where I'm trying to put on 30lbs over the next 6 months.

        It sounds like you perform a mild version of back-loading, which is something I might consider next year in the beginning of off-season. Granted, my carb back-load will consist of 300-400g of carbs from 7-10PM and less than 100g throughout the day prior to that.

        It sounds like you have found something that works. If I were to take a low carb diet approach, I have to use 600-1000kcals of MCT oils, which in itself is a very anabolic thing to do, and of course drinking BCAA's all the time.

        BCAA's can be a life-saver for keto and near-keto diets simply because they will be the preferred amino acid by your muscles to consume when under intense training. BCAA's in this sense are "anti-catabolic".
      1. Matthersby's Avatar
        Matthersby -
        Good info up in here...
      1. TexasGuy's Avatar
        TexasGuy -
        Waiting for the "yeah it's science but totally junk science" crowd...
      1. TheMovement's Avatar
        TheMovement -
        I think the study hits right on, but to each his own lol
      1. mcc23's Avatar
        mcc23 -
        Originally Posted by TheMovement View Post
        I think the study hits right on, but to each his own lol
        Oh rly? Glad we have your approval. Phew
      1. MANotaur's Avatar
        MANotaur -
        Originally Posted by fueledpassion View Post
        There is no doubt that it works to get you lean and keep you lean. I just find that with my fast metabolism it isn't ideal for bulking, especially in my case where I'm trying to put on 30lbs over the next 6 months.

        It sounds like you perform a mild version of back-loading, which is something I might consider next year in the beginning of off-season. Granted, my carb back-load will consist of 300-400g of carbs from 7-10PM and less than 100g throughout the day prior to that.

        It sounds like you have found something that works. If I were to take a low carb diet approach, I have to use 600-1000kcals of MCT oils, which in itself is a very anabolic thing to do, and of course drinking BCAA's all the time.

        BCAA's can be a life-saver for keto and near-keto diets simply because they will be the preferred amino acid by your muscles to consume when under intense training. BCAA's in this sense are "anti-catabolic".

        Yeah I found that out per chance. I really had no idea about back loading. I dont fully agree with the whole concept that kiefer lays out because I eat alot of things like squash and zuchini and eggplant that are are fairly carb dense. Im usually around 100-120 grams carbs per day so im definately not keto lol. It just make sense to me that sense starches are a very fast source of energy-if your not immediately going to use that energy it would make more sense to not consume it.

        but dang bro 30 pounds in six months! thats crazy! Are you gonna log that?

        and your absolutely right about bcaas. Im always drinking them through out the day. I go through about 20-30 grams free form throughout the day.

        Ive still got a lot to learn and theres little things here and there that im tweaking and changing. all in due time i guess. Its taking me 12 years to learn to lift right and consistently and i guess its gonna be a life time endeavor trying to figure out my diet
      1. fueledpassion's Avatar
        fueledpassion -
        Originally Posted by MANotaur View Post
        Yeah I found that out per chance. I really had no idea about back loading. I dont fully agree with the whole concept that kiefer lays out because I eat alot of things like squash and zuchini and eggplant that are are fairly carb dense. Im usually around 100-120 grams carbs per day so im definately not keto lol. It just make sense to me that sense starches are a very fast source of energy-if your not immediately going to use that energy it would make more sense to not consume it.

        but dang bro 30 pounds in six months! thats crazy! Are you gonna log that?

        and your absolutely right about bcaas. Im always drinking them through out the day. I go through about 20-30 grams free form throughout the day.

        Ive still got a lot to learn and theres little things here and there that im tweaking and changing. all in due time i guess. Its taking me 12 years to learn to lift right and consistently and i guess its gonna be a life time endeavor trying to figure out my diet
        I'll log the last 20lbs. I started 6 weeks ago and I'm up 10-12lbs already so only 20lbs to go.. That puts me @ the 190lbs mark.

        I'll be reaching out for help with Super DMZ 2.0 + GHRP-6/CJC DAC combo. Should see 15lbs from that alone then the last 5lbs on my own. Since I run TRT, I never have issues "bouncing back" or losing gains. So I'll probably run a 6 week log of that..

        100-120g carbs, lol.. yeah thats about how much I bring in 3-4 weeks out from competition, lol. Currently while bulking I bring in 400-550g per day, and I'm only 5'5" and 170lbs, lol.

        190lbs is gonna be ridiculous! I'm sure I'll see 600+ grams per day in carbs alone.
      1. MANotaur's Avatar
        MANotaur -
        Originally Posted by fueledpassion View Post
        I'll log the last 20lbs. I started 6 weeks ago and I'm up 10-12lbs already so only 20lbs to go.. That puts me @ the 190lbs mark.

        I'll be reaching out for help with Super DMZ 2.0 + GHRP-6/CJC DAC combo. Should see 15lbs from that alone then the last 5lbs on my own. Since I run TRT, I never have issues "bouncing back" or losing gains. So I'll probably run a 6 week log of that..

        100-120g carbs, lol.. yeah thats about how much I bring in 3-4 weeks out from competition, lol. Currently while bulking I bring in 400-550g per day, and I'm only 5'5" and 170lbs, lol.

        190lbs is gonna be ridiculous! I'm sure I'll see 600+ grams per day in carbs alone.
        Keep me posted! i wanna follow that ish! I about to self perscribe my trt lol. After i finish this LOOONG ass cycle I got planned i think im gonna start.

        I dont compete or anything but if i ever decide to im trying to soak in as much knowledge as I can!

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