SERUM LEPTIN LEVELS AND ENERGY-EXPENDITURE IN NORMAL-WEIGHT WOMEN

To investigate whether circulating leptin levels are associated with e nergy expenditure in healthy humans, doubly labeled water energy measu rements and food intake assessment were carried out in 27 women (mean age, 48.6 years; weight, 61.9 kg; body mass index, 23.2). Energy expen diture was determined over 13 days. Food intake was measured by 7-day food records. Leptin was measured by radioimmunoassay. Leptin level wa s strongly associated with percentage body fat (r = 0.59; p < 0.001), fat mass (r = 0.60; p < 0.001), and body mass index (r = 0.41; p = 0.0 3), but no correlation was observed with energy expenditure (r = 0.02; p = 0.93). After controlling for percentage body fat, a positive asso ciation of leptin level with energy expenditure of marginal significan ce (p = 0.06) was observed. There were no significant univariate assoc iations of age, physical activity, lean body mass, height, or dietary variables with leptin level. When controlling for body fat, a signific ant positive correlation was observed for percent energy from carbohyd rate and negative correlations with dietary fat and alcohol intake. Th ese findings confirm previous associations between leptin and body fat content and suggest a relationship between serum leptin and energy ex penditure level in healthy humans.