Association of leptin and hunger-satiety ratings in obese women

To measure leptin, insulin and cholecystokinin (CCK) concentrations in obese women on calorie restriction and to determine their correlation with hunger-satiety ratings. Although it has been proposed to play a role in appetite regulation, the effects of physiological concentrations of these hormones on hunger-satiety in humans have not yet been well established. Prospective metabolic study. A two week 'wash-in period' followed by a three-week observation period, during which each subject underwent six measurements of satiety, blood parameters and body weight. Energy Metabolism Research Unit, Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA. 22 moderately to severely overweight women (mean age: 45 +/- 8 y; body mass index (BMI): 33 +/- 6 kg/m2). Energy restriction, in the form of a 3.3 MJ (800 kcal) diet during five weeks. Fasting blood levels of leptin, insulin, glucose and CCK, fasting hunger-satiety scores and body weight. The mean (+/- s.d.) fasting serum leptin concentration at the beginning of the observation period was 26.1 +/- 15.9 ng/ml (range: 6.7-59.8 ng/ml). Leptin concentrations correlated positively with body weight (P < 0.0001). Furthermore, reductions in body weight were associated with decreases in fasting leptin levels (P = 0.002). Leptin concentrations correlated with serum levels of insulin (P = 0.0001) and CCK (P = 0.06), but in multivariate analysis including insulin, CCK and glucose, only leptin had a significant relationship with satiety (P = 0.04). This relationship was linear. These results confirm the association between leptin levels, body weight and serum insulin. We also showed that higher serum leptin levels correlated with greater feelings of fullness, a relationship which was not blunted in the more obese subjects. These findings suggest that leptin is a satiety hormone that reduces appetite, even in obese individuals, and that weight gain must be due to other factors, overriding this feed-back regulation.