By Dena McDowell, MS, RD

Contrary to marketing claims, a high-protein/low-carbohydrate diet isn’t necessary for athletes to build muscle, increase lean body mass, and prevent fatty weight gain. In fact, following this advice may impair performance and lead to long-term health consequences. This article dispels the myths surrounding the ideal diet for athletes, especially body builders.

Carbohydrates are good for athletes!

The most important fuel source for athletes is carbohydrates. Carbs provide energy to the muscles. In fact, the body converts them into energy more efficiently than either protein or fat. Carbohydrates are also the only fuel that can be used in anaerobic activities where the muscles do not get enough oxygen (think sprinting or weight lifting). Carbohydrates will not make you fat as many people believe. Over-consuming extra calories in any form (carbohydrates, protein or fat) will result in unwanted weight gain.

Carbohydrates cause a hormonal response in the body. The hormone insulin is secreted when carbohydrates are eaten. Insulin is responsible for transporting carbohydrates into the muscles and liver for future use. It also helps move amino acids (protein) into muscles for muscle building, maintenance, and repair.

If you are an athlete, it is important to eat a diet high in carbohydrates. Approximately 55-60% of your calories should come from carbohydrate-rich, whole foods (i.e. not refined or processed). Good sources of carbohydrates include whole wheat breads and crackers, whole wheat pasta, brown rice, oatmeal, and fruits and vegetables. These foods provide carbohydrates in form of glucose that the body uses as fuel or puts in “storage”. Carbohydrates provide important B vitamins (thiamine, riboflavin, folate and niacin) as well as iron, chromium, magnesium, and phosphorus.

Eat protein sparingly

Protein is also a necessary fuel. It helps with the production of hormones, enzymes, and blood cells, as well as assists with immune function. Another one of its functions is to build and repair muscles. Protein is the body’s second usable fuel source; the body uses it after it has used up all its carbohydrates. Eating a diet with excess protein does not give you bigger muscles. On the contrary—eating too much protein may result in extra weight in the form of fat.

Whether they’re carbohydrates, protein, or fat, extra calorie intake results in weight gain. Research shows that weight lifting utilizes carbohydrates, not protein or fat. Only carbohydrates can be oxidized rapidly enough to meet the energy needs in the muscle cells. Eating too much protein may inhibit your peak performance when working out. If you replace protein for carbohydrates, your body will not be able to use its energy as efficiently, thus causing you to “hit the wall” or “bonk.” Dehydration may also occur due to the fact that carbohydrates carry 4 times as much water as protein. Other risks include kidney impairment, hypoglycemia (low blood sugar), and increased calcium excretion. The resulting lack of vitamins, minerals and antioxidants can increase the risk of osteoporosis and certain types of cancer.

Protein requirements for athletes are higher than non-athletes. Ranges for athletes depend on the type, intensity and duration of the activity. An athlete may need between 1.3 to 1.7 grams per kilogram of body weight compared to non-athletes who only need between 0.8-1.2 grams per kilogram body weight.

Ideal nutrition for athletes

To maximize sports performance, athletes should pay special attention to the types and amounts of food in their diets. A typical athletic diet should be mostly carbohydrates with 55-60% of the calories coming from carbohydrate-rich foods. Between 12-15% of an athlete’s calories should come from protein sources such as meat, legumes, nuts, cheese, milk and soy. Fat should make up the remaining 25-30% of the calories. Increasing protein while decreasing carbohydrates may impair sport performance as well as cause long-term health problems.

For further information on is it good for athletes to eat protein see the following article from TheDietChannel: Protein & Your Body: When to Add Protein to Your Diet.