How much protein do you need? The U.S.D.A. says 35 percent of your diet should come from protein. For 14- to 18-year old males, that equals roughly 50 grams per day, and for females in that age group, about 46 grams. But that recommendation doesn't take into account the elevated activity level of athletes.
According Mike Nelson, MS, CSCS, "The generally established recommendation is just to make sure you don't have a deficiency. It's not designed to help you perform better for your sport." He recommends that athletes eat at least .7 grams of protein per pound of body weight. So a 180-pound teenage football player should aim for about 126 grams a day. (See How Protein Makes Muscles Bigger.)
Athletes should not exceed 1.5 grams of protein per pound of body weight. Nelson adds. "While there's no conclusive evidence that too much protein harms the body, anything taken in excess can have potentially damaging effects." (For more information on the subject, see Will Eating Too Much Protein Harm Your Health?)