Is there a limit to how much protein your body can absorb at one sitting? Nutrition Diva weighs in on this widespread rumor.
Nutrition Diva reader Thomas writes:
"Some people claim that the body can't absorb more than 20-30 grams of protein at a time. Others insist that your body utilizes all the protein you take in. Who is right? Is a post-workout shake with 50 grams of protein a waste?"
This idea that the body can only utilize a certain amount of protein at one sitting has become widely accepted nutrition lore. But is there any validity to the claim? It all comes down to what exactly you mean by "utilizing" protein.
This notion about protein seems to have gotten started on body-building forums - and this may be the main source of some of the confusion. Body-builders are particularly interested in protein's ability to build and repair muscles. And there does seem to be a limit to how much protein the body can use for muscle synthesis at a given time.
If building muscles is your goal, you'll get more benefit by spreading your protein intake out among all of your meals.
In one study, researchers found that a meal containing 30 grams of protein boosted muscle-building activity by about 50%. That's the amount of protein you'd get in a 3-ounce serving of chicken breast or a quarter-pound of lean beef. It turned out, however, that increasing the amount of protein in the meal didn't create a bigger boost in muscle synthesis. On average, subjects who ate 90 grams of protein at a meal got exactly the same benefit as subjects who ate 30 grams.
The precise amount of protein at which the muscle-building effects peak will vary from person to person, of course. Someone with a very large or muscular body, or someone who is engaged in heavy workouts might be able to use a little more protein than someone who is smaller or not as athletic. But, in general, if building muscles is your goal, you're probably better of spreading your protein intake out among all of your meals than by eating the entire day's allowance at one meal.
However, those who claim that all of the protein you eat is utilized are also right - because building muscle is only one of the things that our bodies use protein for.