Guidance from health professionals will assist the significant proportion of athletes who desire a change in their body weight. Athletes who use drastic food or fluid restriction to lose weight may experience negative consequences, including loss of lean tissue, hormonal disturbances, and performance impairment. Excess food consumption for weight gain can increase body fat and risk factors for chronic diseases. Weight change is best done during the off-season, modifying energy intake up or down by 500 kcal/d. Adequate carbohydrate (60%-65%, > 5 g/kg) and protein (15%, 1.2-1.8 g/kg) and a low fat intake (20%-25%) is appropriate for either weight loss or gain. The athletic staff should be knowledgeable about the latest rules related to weight and appropriate weight control methods so they may guide their athletes using modest, safe approaches that will not negatively affect health or performance.