How much protein is enough for people who weight train?

This is a little like asking: how much money should I pay for a car? It depends on the circumstances. How much protein is right for you depends on:

    • general health,
    • age,
    • body size,
    • stage of training,
    • the intensity of the weight training,
    • how much aerobic exercise is being done,
    • training goals,
    • if muscle is being gained,
    • if overall body weight is decreasing (which may actually raise protein needs)
    • Carbohydrate intake

The last consideration arises because exercisers need good carbohydrate intake to avoid high breakdown of protein. Generally, the body tries to make a fuel mixture that contains fat + carbohydrate + protein, with protein being the lowest %.

How much protein do you need?

If the amount of carbohydrate available gets low, the body uses more protein for fuel. Since this “wastes” protein, and doesn’t produce better energy, it’s desirable to spare protein by eating adequate carbohydrate. In contrast, proponents of ketogenic diets claim that people on these diets can sub ketones for carbs. I won’t debate that issue here.

The Recommended Dietary Allowance (RDA) for protein is set at 0.8 g/kg body weight (0.36 g/lb). That translates to 50 g for a 140 lb person and 72 g for a 200 lb person. If a person does weight training, protein needs should be increased. Some of this extra protein goes into the energy fuel mix; some replaces protein lost during muscle tissue breakdown and repair (though much of the amino acids from the broken proteins can recycle back into new protein). In addition, some protein can go to muscle weight gain if that is occurring. However, none of this seems to require a huge jump in protein intake. For that reason, many in the biomedical community used to dismiss any notion that exercisers need much more protein than the RDA.

The Concept of “Surplus” Protein

Eventually, a concept of “surplus” protein for exercisers emerged. The idea is that having extra protein stimulates muscle protein production and slows muscle protein loss. Some respond by saying that getting this extra protein poses no practical concern. After all, many people in the USA eat way above the RDA for protein. For example, an article on a Mayo Clinic site states the following: “Contrary to all the hype that everyone needs more protein, most Americans get twice as much as they need” (MayoClinic).

A Different Conclusion

A different conclusion was reached by researchers who analyzed 22 studies that added protein to exercisers’ normal diets (1). In some cases, this addition was done with food, but most studies used supplements (which made for easier study design). The studies included young and older subjects. When the researchers pooled the data, lean body weight gain and/or one rep max leg press increased with the added protein intake. The amount of added protein ranged from modest (6 g) to very high (84 g).

My Research Group’s Study Suggests Not Everyone Eats Enough Protein

Similar to some of the pooled studies, my research group did a study (2) where soy or whey protein bars were added to the diet of male college students. We provided one 15 gram protein bar as soy or whey, twice a day for 10 weeks. Each student was post-beginner, but not advanced.

The subjects did multiple exercises for 3 sets of fairy low reps with weights considered heavy for the trainees. A control group did the same exercise program, but without the extra protein.

The control group did not gain lean body mass. Both protein groups gained body mass. So, this study further supports the idea that not everyone eats enough protein for maximal muscle weight gain.

Is It a Given That You Should Eat More Protein?

Does all this mean you should automatically eat more protein? Not necessarily. For lots of people in the studies used by the statisticians, increasing protein intake did not improve muscle mass or leg press performance.

Another big problem with these studies is that they didn’t start with consistent background protein intake. Ideally, I’d love to see studies that start with fit people who have consistently eaten an RDA level of protein. Then, I’d like to see different groups consume graded amounts of protein (ie 25% above the RDA, 50% above, 100% above, etc.). Unfortunately, it would be hard to find a bunch of fit people who have been eating around the RDA amounts of protein. Alternatively, one could deplete people down to RDA levels for a few months before beginning the study intervention. However, most people who exercise wouldn’t volunteer for that or would drop out before the study ended.

Despite these problems, the statisticians doing the analysis of the 22 studies (1) felt that before adding the extra protein, the subjects were generally eating at least 1.2 g protein/kg body weight (1.5 times the RDA, which comes to 98 g for a 180 lb person). Thus, for at least some people, this intake did not support maximum muscle gain. A new statistical analysis (3) has now been done. This analysis used some of the same studies from the earlier analysis, but also looked at other studies. This new analysis concluded that maximum benefit peaks at 1.6 g protein/kg body weight (131g for a 180 lb person).

Not everyone in all the studies showed benefits from going this high. So, you may not have to hit this mark for your best results.

Going higher than 1.6 g/kg has not consistently shown any benefits. In fact, two studies found no effect of going really high on the g protein/kg body weight (4,5). However, it should be noted that in these studies, as well as in most of the studies in this area, the subjects were not trying to gain or lose overall body weight. Both those conditions may raise protein recommendations a little.

Bodybuilders’ Need For Protein

Another issue is protein needs for a bodybuilder. The studies noted above generally deal with people who weight train, but not as bodybuilders. Such people, and maybe a few other types of athletes, can carry a very high percent muscle. Some trainers, like Jim Stoppani of Bodybuilding.com, claim that bodybuilders need really high protein intakes (JS). Stoppani bases this claim largely on his personal experience. He also cites some studies, though their interpretation can be debated. Even so, I don’t see extensive published research that contradicts Jim Stoppani’s experience. In fact, one study (6), which was published in a prominent nutrition journal, says he could be right. In this research, a biochemical measure was utilized rather than muscle gain or exercise performance. For male bodybuilders, the study measure didn’t max out until protein intake reached 2.2g/kg body weight (180g for a 180 lb person). Although this is just one study, and only used one type of measure in one set of circumstances, it does support the experience reported by many bodybuilders.

Conclusion

If you’re not a bodybuilder or something similar, but do a lot of intense resistance exercise, going up to 1.6 g/kg (0.87 g/lb) would likely give what you need (and possibly more than you need). If you take a more moderate training approach, 1.2 g/kg might be more reasonable. The American College of Sports Medicine recommends 1.2-1.7 g/kg for resistance exercisers (ACSM). This corresponds to about what I am suggesting here, though as I mentioned throughout the article, a lot of factors can alter the situation (ie. weight gain or loss, being a bodybuilder, doing a lot of aerobic exercises, age, etc.).

One last comment: you probably don’t have to fear overwhelming the body’s absorption capacities with too much protein at once. This concern has been based on a narrow interpretation of some research data. In contrast, a study (7) has suggested that the body possesses a large protein absorption capacity. Even so, it’s still a good idea to spread out your protein intake.

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  1. Cermak NM, Res PT, de Groot LCPGM, Saris WHM, van Loon LJC. Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. The American Journal of Clinical Nutrition. 2012;96:1454-1464.
  2. Brown EC, DiSilvestro RA, Babaknia A, Devor ST. Soy versus whey protein bars: effects on exercise training impact on lean body mass and antioxidant status. Nutrition Journal. 2004;3:22.
  3. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52:376-384.
  4. Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Journal of The International Society of Sports Nutrition. 2014;11:19.
  5. Antonio J, Ellerbroek A, Silver T, Vargas L, Peacock C. The effects of a high protein diet on indices of health and body composition–a crossover trial in resistance-trained men. Journal of The International Society of Sports Nutrition. 2016;13:3.
  6. Bandegan A, Courtney-Martin G, Rafii M, Pencharz PB, Lemon PW. Indicator Amino Acid-Derived Estimate of Dietary Protein Requirement for Male Bodybuilders on a Nontraining Day Is Several-Fold Greater than the Current Recommended Dietary Allowance. The Journal of Nutrition. 2017;147:850-857.
  7. Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? Clinical Nutrition (Edinburgh, Scotland). 2013;32:309-313.

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