This study assessed nutritional and body weight patterns in 6 female body- builders approximately a month before and after a competition. The women kept dietary and body weight records and two of them also agreed to collect morning urine samples to provide information about their menstrual cycle. All women lost weight before and gained weight after competition. Energy intake was modestly restricted and the subjects consumed a moderate-protein, low-fat, high-carbohydrate diet just prior to competition. Energy intake doubled, and total grams of fat increased approximately tenfold just after competition. Urinary data indicated that the cycle following competition was prolonged, with reduced reproductive hormone concentrations. In summary, the women practiced extreme dietary control while preparing for a competi- tion but followed the event with a higher energy and fat intake. These changes in diet and body weight may contribute to the disturbances previously observed in the menstrual cycle of these athletes.