Dear Liiiisa,

You're on the right track, but athletes' protein, carbohydrate, fat, and calorie requirements can vary, depending on many factors. Athletes' needs depend on their fitness level, type of training, body size and composition, and performance goals — what they're trying to achieve.

Let's talk about endurance athletes first. They train aerobically for an hour or more at a time, which requires a lot of energy. Since muscles prefer to burn carbohydrates for fuel, serious aerobic exercisers need plenty of these. The body stores carbs in muscle tissue (and liver) as glycogen. Muscles utilize glycogen for fuel during exercise. When glycogen runs low, the body may resort to burning protein for energy. When this happens, endurance athletes' protein needs increase. Why would glycogen levels diminish? Their stores are limited, dropping when exercisers work out at a moderate intensity for an extended period of time (90 minutes or more) without taking in any carbohydrates. These levels can remain low if people exercise day after day without eating enough carbs to replenish their supply. In either case, their bodies resort to utilizing protein for energy during workouts. This makes exercise tough; the result is fatigue. In running, this is referred to as "bonking" or "hitting the wall," and it's just like it sounds — exhausting. Adding carbohydrates to your overall eating plan prevents this from happening. It's known as "sparing protein breakdown." Eating a snack just prior to exercise may be helpful, but does not entirely fuel that activity, because there won't be enough time to store those carbs as glycogen. It's the previous meals eaten that significantly contribute to glycogen levels.

For intense daily exercisers, those engaging in double training sessions, or people participating in multi-event tournaments or meets, recovery nutrition is essential. This means eating a carbohydrate-rich snack or meal immediately after training. Research has shown that enzymes promoting glycogen storage hit their peak 1 - 2 hours after exercise. Taking advantage of this time window can help stoke up glycogen stores and spare protein breakdown.

Resistance exercisers are those primarily involved in weight lifting activities. Without doing aerobic exercise, these folks typically don't burn as many calories as endurance athletes. Their protein needs depend on whether or not they are trying to build or maintain muscle mass.

The following is a general guide for protein and carbohydrate intake. A person's specific needs may vary depending on the duration and intensity of one's activity and fitness level. The numbers below are a factor of your body weight. A person's weight in kilograms (kg) is equal to his or her body weight in pounds divided by 2.2. (For more details about dietary sources of carbohydrate and protein, check out Does carbohydrate become body fat?, Very low protein diet — Good for health?, and Do bodybuilders and other weightlifters need more protein?.)

Protein (the amount calculated is for daily intake)

• High intensity endurance athlete: 1.2 - 1.4 g/kg of body weight
• Resistance training to maintain muscle mass: 1.0 g/kg
• Resistance training to increase muscle mass: 1.4 - 1.8 g/kg

Carbohydrates

Besides carbohydrate and protein intake, it's also important for endurance athletes to consume enough calories in general to fuel training as well as activities of daily living; otherwise, protein will still be burned as fuel instead of being used for muscle-tissue repair and other important functions. Resistance athletes trying to build muscle mass also have to take in sufficient calories to support muscle development.

Although we can't precisely manipulate the nutrients our bodies utilize at any given time, endurance athletes can help spare protein by improving fitness level, consuming enough calories, and eating plenty of the right foods at the proper times. Hopefully this information will help you as your hitting the books and hitting the gym!

Alice

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