If you are an active athlete, you need to eat -- a lot! Low-calorie diets and aerobic exercise can compromise ...

strength. Muscle building requires muscle tension, anabolic hormones, amino acids, calories, and adequate recovery. Athletes who try to cut fat through a combination of low-calorie diets and endurance exercise, can compromise protein synthesis and muscle growth. Dr. Gustavo Nader from the Children’s National Medical Center in Washington D.C., in a review of literature, concluded that training simultaneously for muscle growth and endurance compromises strength, because strength and endurance training initiates different signaling pathways within the muscle cells. Endurance training activates AMPK— an important energy-sensing enzyme that monitors cellular energy status. AMPK inhibits mTOR, a cell-signaling chemical that promotes muscle protein synthesis and muscle hypertrophy. Minimize body fat year-round, so you don’t have to reduce large amounts prior to competitions. Emphasize high-intensity exercise (i.e., interval training or wind sprints) when trying to lose body fat to avoid stimulating AMPK. Finally, consume plenty of protein (1.5 grams of protein per kilogram bodyweight per day) to curb appetite and minimize muscle wasting during weight loss. (Medicine Science Sports Exercise, 38: 1965-1970, 2006)