Protein: A Guide to your needs.

If you want to build muscle or lose weight, there's nothing more important you can add to your diet than protein. But the concept of "protein" can be confusing, even to me, and I'm a nutritionist. Between all those pro and con news reports, the protein-boosting supplements, and the myths you hear at the gym, it's tough to figure out the truth. That's why we're stepping into the ring: to help you separate protein fact from protein fiction, once and for all.

How much protein does the average guy need?
Depends on whether you work out or not and how strenuous your workouts actually are. Your average desk-bound male requires just 0.36 grams of protein per pound of body weight per day.

But exercise can nearly double those requirements. For endurance athletes, Peter Lemon, a professor of exercise nutrition at the University of Western Ontario, recommends getting between 0.5 and 0.7 grams of protein per pound of body weight. "For strength athletes, those numbers are even higher--generally between 0.7 and 0.8 grams of protein per pound of body weight," he says. If you've been shooting for a gram of protein per pound of body weight--or more--you're overdoing it. Your body won't be able to process those extra calories, and they'll ultimately end up as just one thing: fat.

Will cutting carbs help my muscles grow faster?
Short answer: no. As effective as high-protein diets are for losing weight, you still need carbs and fat for maximum muscle growth. Your body uses carbs for energy during exercise. If your cache of carbs is low, your body will use protein as an alternate fuel source, and your muscles won't grow as much as they would if you were feeding them a cocktail of protein and carbs. As for the fat, it's vital for the production of muscle-building testosterone. (Studies show that guys who eat higher-fat diets also have higher testosterone levels.)

Could eating too much protein be dangerous?
There's research suggesting that too much protein can leave you dehydrated and may increase your risk for gout, kidney stones, and osteoporosis, as well as some forms of cancer. But studies have also shown that too much of anything, from vitamins to water, can be bad for your health. The bottom line? Excess carbs and fat are still associated with health risks, but the success of high-protein diets is no excuse to scarf down a whole pig or an entire side of beef. Keep your appetite in check, though, and a high-protein diet should not negatively impact your health.

Should I consider taking a protein supplement?
Yes--if you aren't getting the amount of protein your body requires based on your activity level. You can check nutrition labels and add up grams of protein on your own, or just remember the numbers 1, 5, 10, 15, 25 to roughly estimate protein intake. (That's 1 gram of protein for every serving of fruit and vegetables, 5 for every egg or handful of nuts you eat, 10 for every cup of milk or yogurt, 15 for every cup of beans or half-cup of cottage cheese, and 25 for every 3-4 ounce serving of meat.)

When's the best time to drink a protein shake?
Although it can vary by brand, most experts recommend taking protein in two servings: one an hour or so before your workout to tank off your body's energy reserves, and another dose immediately after you work out to help repair muscle damage and fuel the growth of new muscles.

Which is the better protein supplement: whey or casein?
Surprisingly, blending both types of protein together and taking them as a mixture may provide better benefits than taking either one alone. French researchers recently discovered that casein supplies a much steadier stream of amino acids to the body--much like a complex carbohydrate, which breaks down slowly in the body. Whey, on the other hand, is absorbed more quickly and provides a more immediate supply of amino acids to the body (much like a simple carbohydrate). It makes sense then that a combination of whey and casein would supply the body with the maximum dose of amino acids needed for both immediate and long-term muscle growth. (Can't find a blend you like? Buy your favorite whey and casein supplements and mix 'em together.)

Is there any benefit to getting protein from bars or shakes instead of whole foods?
No. Shakes and protein bars might make it easier to meet your daily protein requirements, but in the end, high-protein foods like meat, eggs, peanut butter, and nuts may actually be more satisfying because they have higher fat content and take longer to digest than shakes or bars.

What happens if I don't get all the protein I need? Will my muscles shrink?
Absolutely not. If you're eating an appropriate amount of protein in general, an occasional low-protein day will not affect muscle growth. The only reasons muscles would get smaller are from lack of use, injury, or severe calorie restriction.