Will dieting affect my performance?

Many athletes believe that losing weight improves their chances of winning but, in practice, rapid or strict dieting can have an adverse effect on your performance.

Firstly, rapid weight loss results in a diminished aerobic capacity. A drop of up to 5% has been measured in athletes who had lost just 2-3% of body weight through dehydration. A loss of 10% can occur in those who lose weight through strict dieting.

Anaerobic performance, strength and muscular endurance are also decreased, although researchers have found that strength (expressed against body weight) can actually improve after gradual weight loss. Strict dieting also reduces vitamin and mineral status, since a lower food intake almost always means a lower intake of micronutrients. Supplements may, therefore, be advisable if dieting for more than three weeks.

Prolonged dieting or food restriction can have more serious health consequences. In female athletes, low body weight and body fat have been linked with menstrual irregularities, amenorrhoea and stress fractures; in male athletes, with reduced testosterone production. It has also been suggested that the combination of intense training, food restriction and the psychological pressure for extreme leanness may precipitate disordered eating and clinical eating disorders in some athletes. Scientists say that those who attempt to lose body fat for appearance are more likely to develop an eating disorder than those who control it only for performance purposes.

Rapid Weight Loss

To make weight for a competition (e.g. boxing, bodybuilding, judo), athletes may resort to rapid weight loss methods, such as fasting, dehydration, exercising in sweat suits, saunas, diet pills, laxatives, diuretics or self induced vomiting. Weight losses of 10 Ib in 3 days are not uncommon. In one study [1] of 180 female athletes, 32% admitted they used more than one of these methods. In another [2], 15% of young female swimmers said they had tried one of these methods.

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