Leptin does not respond to 48 h fat deposition or mobilization in women.

OBJECTIVE:: To test the hypothesis that acute responses of plasma leptin concentration to energy balance manipulation are mediated by fat flux. DESIGN:: Ten healthy women aged 31-63 y, mass 48-113.5 kg, fat mass 8.5-62.5 kg, were studied for 3 days in a whole-body calorimeter on two occasions. After a control day (D1) during which energy balance was maintained, diet was manipulated to induce fat deposition (FD) or mobilization (FM) of 50 g/day for 2 days (D2 & D3). A difference totalling of 194+/-18.6 g fat was achieved between manipulations without significant effects on carbohydrate or protein balance. Fasting plasma leptin was measured on D2 and D4. RESULTS:: After the control day plasma leptin concentration averaged 19.01+/-9.8 ng/ml, and was found to be linearly related to body fat mass. After 2 days manipulation of fat balance, leptin concentrations were 21.4+/-10.3 ng/ml (FD) and 21.2+/-11.3 ng/ml (FM). There was no significant difference between treatments in either control day or postmanipulation leptin concentrations, nor did the treatments induce any differences in glucose or insulin concentration responses. CONCLUSION:: Although in states of energy balance leptin concentration is linearly related to fat mass, acute modulation of leptin concentration during energy imbalance is not mediated by fat flux.International Journal of Obesity (2003) 27, 457-462. doi:10.1038/sj.ijo.0802252