[Nutrition and health--ideal body weight for the obese unrealistic; health benefit by moderate sustained weight loss].

The aim of achieving a normal or ideal body weight in the treatment of obesity is an obsolete goal. It stems from the time that obesity was not yet seen as a chronic incurable disease. A more realistic treatment goal is to reduce the body weight by 10-15% over a prolonged period of time. This moderate weight loss will result in a decreased risk for and incidence of obesity-associated diseases. Weight reduction and maintenance is countered by a decrease in resting-energy expenditure and in thermogenesis by food intake, a decreased energy expenditure through physical exercise, a reduced fat oxidation, a relative leptin deficiency and an excess of the gastrointestinal hormone ghrelin. Just as with hypertension and diabetes, the only option is life-long management with the normalisation of abnormal values within a given range.