The average American eats around 100 grams of protein a day — double the USDA-recommended 50 grams a day. But that 50 grams is the minimum amount needed to prevent malnutrition in an average-sized man, and most people understand that it’s well short of what you need to be healthy.
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On the other hand, most people who get into weightlifting actually overestimate how much protein they need to maximize muscle growth.
The truth is somewhere in the middle: You need to eat more protein than most people realize, but you don’t need to buy a second freezer to hold all your steaks. Here’s what the research says about protein intake.
Protein Intake Myths That May Be Messing up Your Nutritional Goals
1. You Should Eat 1 Gram Per Pound Per Day
If you read bodybuilding websites, you’ll see that most of them repeat the idea that you need at least 1 gram of protein per pound of body weight per day. This number has become so deeply entrenched in the fitness world that few people even think to question why the optimal protein intake would work out to such a convenient, round integer.
Research has consistently failed to back this number up. A 1992 study by Lemon et al. observed no difference in muscle mass or strength gains between novice bodybuilders eating 0.61 grams per pound or 1.19 grams per pound over a four-week period. Various studies since then have suggested optimal protein intakes in the range of 0.55 to 0.82 grams per pound of body weight per day.
A 2017 meta-analysis found no added benefit to eating 1.32 versus 0.82 grams per pound per day.
"Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET [resistance training] in healthy adults," another meta-analysis, published in March 2018, concluded. "Increasing age reduces — and training experience increases — the efficacy of protein supplementation during RET.
"With protein supplementation, protein intakes at amounts greater than around 1.6 grams per kilogram per day do not further contribute RET-induced gains in FFM.”
2. You Need More Protein if You're an Advanced Athlete
You might think that you need more protein if you train harder than the subjects in these studies, or are more advanced than they are.
Regarding training harder, you’d be right. Studies have shown that people who do resistance training need more protein than those who do endurance training, who — in turn — need more than sedentary people. So, it does stand to reason that people who train harder could benefit from a somewhat higher protein intake.
Regarding training status, however, the truth is decidedly counterintuitive: the more advanced you are, the less protein you need. Tarnopolsky, MacDougall, and Atkinson found that 0.45 grams per pound was sufficient to maintain lean body mass in elite bodybuilders, and suggested that 0.55 grams per pound was the absolute maximum beyond which benefits would likely be visible.
A 2006 study on protein turnover in resistance trainees concluded that "dietary requirements for protein in novice resistance-trained athletes are not higher, but lower, after resistance training.”
It appears that, as trainees get more advanced, their bodies adapt to exercise, and less muscle tissue breaks down after workouts. As a result, they don’t need as much protein to repair their muscles after each workout.
3. Too Much Protein Will Harm You
As a foil to the one gram per pound myth, there’s also a popular belief that too much protein can cause kidney damage, but exactly how much protein is "too much" seems to vary from source to source. While it is true that certain kidney pathologies necessitate a low-protein diet, studies have found no indication that a high protein intake causes kidney problems in people with normally-functioning kidneys.
A study published in the International Journal of Sport Nutrition and Exercise Metabolism found that athletes eating up to 1.3 grams per pound per day of protein experienced no kidney issues as a result of that diet. The study concluded that "it appears that protein intake under 2.8 grams per kilogram does not impair renal function in well-trained athletes as indicated by the measures of renal function used in this study.”
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A 2005 study concluded that “although excessive protein intake remains a health concern in individuals with pre-existing renal disease, the literature lacks significant research demonstrating a link between protein intake and the initiation or progression of renal disease in healthy individuals.
"More importantly, evidence suggests that protein-induced changes in renal function are likely a normal adaptive mechanism well within the functional limits of a healthy kidney.”
Practical Guidelines for Protein Intake
Based on the sum total of research, people who do resistance training need somewhere between 0.55 and 0.82 grams of protein per pound of bodyweight per day to maximize muscle protein synthesis. Endurance athletes, such as marathon runners performing minimal resistance training, may not even need that much.
On the other hand, you can go higher if you want to. Protein intakes up to at least 1.3 grams per pound of body weight per day — and probably much higher — are perfectly safe for people with healthy kidneys.
In practical terms, this means that you, as a highly-active athlete, need to make a moderate effort to eat more protein than the average person, but you can still eat a fairly normal meal plan — and you certainly don’t need to eat 16 chicken breasts a day.