Nutrition and athletic performance -- Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine

The following key points summarize the current energy, nutrient, and fluid recommendations for active adults and competitive athletes noted in this position paper. Sport nutrition experts can further adjust these general recommendations to accommodate the unique concerns of individual athletes regarding health, sports, nutrient needs, food preferences, and body weight and body composition goals.

• During times of high-intensity training, adequate energy needs to be consumed to maintain body weight, maximize the training effects, and maintain health. Low-energy intakes can result in loss of muscle mass, menstrual dysfunction, loss or failure to gain bone density, and increased risk of fatigue, injury, and illness.
• Body weight and composition can affect exercise performance but should not be used as the sole criterion for participation in sports; daily weigh-ins are discouraged. Optimal body-fat levels vary depending upon the sex, age, and heredity of the athlete, as well as the sport itself. Body-fat assessment techniques have inherent variability, thus limiting the precision with which they can be interpreted. If weight loss (fat loss) is desired, it should start earlybefore the competitive season and involve a trained health and nutrition professional.
• Carbohydrates are important to maintain blood-glucose levels during exercise and to replace muscle glycogen. Recommendations for athletes range from 6 to 10 g/kg body weight per day. The amount required depends upon the athletes total daily energy expenditure, type of sport performed, sex of the athlete, and environmental conditions.
• Protein requirements are slightly increased in highly active people. Protein recommendations for endurance athletes are 1.2 to 1.4 g/kg body weight per day, whereas those for resistance and strength-trained athletes may be as high as 1.6 to 1.7 g/kg body weight per day. These recommended protein intakes can generally be met through diet alone, without the use of protein or amino acid supplements, if energy intake is adequate to maintain body weight.
• Fat intake should not be restricted, because there is no performance benefit in consuming a diet with less than 15% of energy from fat, compared with 20% to 25% of energy from fat. Fat is important in the diets of athletes as it provides energy, fat-soluble vitamins, and essential fatty acids. Additionally, there is no scientific basis on which to recommend high-fat diets to athletes.
• The athletes at greatest risk of micronutrient deficiencies are those who restrict energy intake or use severe weight-loss practices, eliminate one or more food groups from their diet, or consume high-carbohydrate diets with low micronutrient density. Athletes should strive to consume diets that provide at least the RDAs/DRIs for all micronutrients from food.
• Dehydration decreases exercise performance; thus, adequate fluid before, during, and after exercise is necessary for health and optimal performance. Athletes should drink enough fluid to balance their fluid losses. Two hours before exercise 400 to 600 mL (14 to 22 oz) of fluid should be consumed, and during exercise 150 to 350 mL (6 to 12 oz) of fluid should be consumed every 15 to 20 minutes depending on tolerance. After exercise the athlete should drink adequate fluids to replace sweat losses during exercise. The athlete needs to drink at least 450 to 675 mL (16 to 24 oz) of fluid for every pound (0.5 kg) of body weight lost during exercise.
• Before exercise, a meal or snack should provide sufficient fluid to maintain hydration, be relatively low in fat and fiber to facilitate gastric emptying and minimize gastrointestinal distress, be relatively high in carbohydrate to maximize maintenance of blood glucose, be moderate in protein, and be composed of foods familiar and well tolerated by the athlete.
• During exercise, the primary goals for nutrient consumption are to replace fluid losses and provide carbohydrate (approximately 30 to 60 g per hour) for the maintenance of blood glucose levels. These nutrition guidelines are especially important for endurance events lasting longer than an hour, when the athlete has not consumed adequate food or fluid before exercise, or if the athlete is exercising in an extreme environment (heat, cold, or altitude).
• After exercise, the dietary goal is to provide adequate energy and carbohydrates to replace muscle glycogen and to ensure rapid recovery. If an athlete is glycogen-depleted after exercise, a carbohydrate intake of 1.5 g/kg body weight during the first 30 minutes and again every 2 hours for 4 to 6 hours will be adequate to replace glycogen stores. Protein consumed after exercise will provide amino acids for the building and repair of muscle tissue. Therefore, athletes should consume a mixed meal providing carbohydrates, protein, and fat soon after a strenuous competition or training session.
• In general, no vitamin and mineral supplements should be required if an athlete is consuming adequate energy from a variety of foods to maintain body weight. Supplementation recommendations unrelated to exercisesuch as folic acid in women of childbearing potentialshould be followed. If an athlete is dieting, eliminating foods or food groups, is sick or recovering from injury, or has a specific micronutrient deficiency, a multivitamin/mineral supplement may be appropriate. No single nutrient supplements should be used without a specific medical or nutritional reason (eg, iron supplements to reverse iron deficiency anemia).
• Athletes should be counseled regarding the use of ergogenic aids, which should be used with caution and only after careful evaluation of the product for safety, efficacy, potency, and legality.
• Vegetarian athletes may be at risk for low energy, protein, and micronutrient intakes because of high intakes of low- energydense foods and the elimination of meat and dairy from the diet. Consultation with a registered dietitian will help to avoid these nutrition problems.