There is little evidence to suggest that low body weight automatically improves sports performance. Diet and performance are inextricably linked - dieting has a major impact on sports performance, as do training and genetic endowment.
Strict dieting will effect performance significantly owing to a reduced vitamins and mineral intake. If dieting is continued for a period of 3 weeks or longer it is advisable to take vitamin supplements to ensure that required vitamin and minerals are obtained.
For female athletes dieting will effect sports performance but may also have additional health implications. Low body weight, strict dieting and low body fat is linked to menstrual irregularities and amenorrhoea. There is also a link between intense training and dieting and eating disorders. A study by Rosen et al illustrated that 32% of female athletes (in a study of 132 female athletes) had tried extreme measures including induced vomiting, dehydration, laxatives, dehydration compulsive exercise to achieve rapid weight loss.
Dieting will have a major impact of sports performance and health. Fogelhorn (1994) found a 5% drop in performance when athletes lost 2.5% of body weight through dehydration. For sports performance an intake of at least than 60% carbohydrate is critical for preserving muscular endurance, aerobic and anaerobic capacity. If consumption falls too low we will deplete glycogen levels and our body may begin to break down muscle as fuel.