If you're into strength training and want to pack on the pounds of solid, lean muscle, you'll want to throw an extra steak on the grill—although you'd be better off with a leaner meat such as chicken or salmon that's low in saturated fats.

As you may have guessed, extra protein is key to building muscle and should account for between 20 to 30 percent of the calories you consume each day (to calculate your total daily calorie requirements, see the related article "Calculate Your Calorie Requirements" at the end of this article). What might surprise you, however, is that you will also need to boost your carbohydrate intake slightly. (Sorry, but your fat percentage remains the same at about 20 to 25 percent, so stop eating those Krispy Kremes on the way to work.)

"Many of the bodybuilders I see are so focused on loading up on proteins that they're not getting enough carbs," says Villacorta. "Bodybuilders should be getting at least 50 percent of their calories from carbs, which are just as important as proteins."

Why the emphasis on carbs? Carbs give your body the fuel it needs to function. If you're not getting enough carbs, your body takes the protein it would have used to build muscle and repurposes it as fuel. By increasing your carbs to between 50 to 60 percent of your daily calories, you allow your protein to be used for what God intended—building enormous pecs.

If you've got the calculator out trying to determine how these percentages translate into real food, Villacorta offers some help: If you're doing light muscle training, you should eat from 0.7 to 0.9 grams of protein for each pound you weigh. If you're more serious about bodybuilding and packing on muscle, plan on putting away one gram of protein per pound of bodyweight, which is the maximum amount of protein you can eat in a day and still see the benefits of muscle growth, says Villacorta. Sure, you can eat more protein, he adds, but it hasn't been proven to do you any good, and it may even put unwanted strain on your kidneys and other organs.

What's almost as important as how much protein you eat, however, is when you eat it. "For bodybuilders," Villacorta insists, "the post-workout meal is key." By eating right after you exercise, you take advantage of all the blood flowing to the muscles—eat a big meal before lifting and all of that blood shifts to your intestines to help with digestion, leaving your muscles high and dry.

Within a half hour of working out—some research even says within 15 minutes—you should eat a meal that contains a three-to-one ratio of carbs to proteins, says Villacorta. For a good post-workout meal, he suggests eating a yogurt, which gives you 15 grams of carbs and eight grams of proteins, and an apple, which supplies an additional 15 grams of carbs. A simple cheese sandwich on wheat bread could also do the trick. Villacorta stresses that athletes don't need supplements to meet their daily protein requirements. "You can get the same thing by eating food," he says, "and it's a lot more fun."

Going the Distance
Training for a marathon? Then get ready to pile on the carbs, because you're going to need them. "It's OK," says Villacorta, "for ultra endurance athletes—those planning a six-hour bike ride or training for a triathlon, for example—to get up to 70 percent of their calories from carbs, depending on the intensity of the workout." Endurance athletes need extra carbs to ensure that their muscles have enough glycogen in storage to keep them running—literally.

As is true for weight lifters, when you get your carbs is just as important as how many you get. Unlike for weight lifters, however, the pre-workout meal for endurance trainers is just as key as the post-workout meal. Not only that, but Villacorta advises that you eat while working out as well.

At the pre-workout meal, endurance athletes want to eat between 0.5 grams to 2.25 grams of carbs for every pound they weigh, depending on when they eat the meal. If you were eating one hour prior to exercise, says Villacorta, you'd eat 0.5 grams of carbs per pound of bodyweight. If you were going to eat two hours before you exercise, then you'd eat about 0.9 grams of carbs per pound of bodyweight. The further in advance of your workout you eat, the more carbs per pound of bodyweight you should eat.

Say, for example, you weigh 150 pounds and you're eating your pre-workout meal two hours before you plan on exercising. You'd need to eat about 135 grams of carbs, Villacorta says, which you could get from combining a fruit shake made with a banana and 10 ounces of orange juice with a peanut butter and jelly sandwich made with two tablespoons each of all-natural peanut butter and jelly spread between two slices of wheat bread.

It's also important to continue feeding your body while you exercise so your muscles don't run out of fuel mid-way through. Villacorta recommends eating between 30 and 60 grams of carbs for every hour of training to improve your performance. That may sound like a lot— especially when you're sprinting for the finish line—but Villacorta recommends carb-laden gels, bars, or beverages, such as Gatorade or Cyotmax, that are easy to eat or drink on the go.

For the post-workout meal, endurance athletes need to put back all the carbs they used up while exercising in order for the body to recover quickly for the next workout. "It's important," says Villacorta, "to eat about 0.75 grams of carbs per pound of bodyweight within 30 minutes after you finish your exercise. Two hours later, you'll want to follow up with a post-post-workout meal consisting of about 0.75 grams of carbs per pound of bodyweight."

Why the strict timetable? It's been proven that these amounts replenish glycogen the most effectively, says Villacorta. Within 30 minutes after exercising, for example, blood is flowing to your muscles and your cells are hungry for glycogen. Because muscles are capable of absorbing more insulin at this time, they're better able to help deposit glucose back into the cells.

Overall, if you are participating in endurance sports, you should feel free to load up on carbs, with at least 60 to 70 percent of your daily calories coming from carbs alone. Round out your daily diet with 20 percent of your calories coming from proteins, and between 10 to 20 percent coming from fats. It's that simple.