Effect of dieting on plasma leptin, soluble leptin receptor, adiponectin and resistin levels in healthy volunteers

OBJECTIVE Recent findings demonstrating important effects of the adipokines on metabolism, energy homeostasis and body weight regulation have prompted research on the possible role of negative energy balance in altering adipocytokine regulation. The goal of this study was to evaluate the effects of a hypocaloric diet in healthy normal-weight volunteers. An additional goal was to help clarify the contribution of restricted caloric intake to altered plasma adipokine levels in the eating disorders anorexia nervosa and bulimia nervosa. DESIGN Participants were studied before and after a 4-week reduced-calorie diet (1000-12000 kcal/day). PATIENTS Subjects included 15 healthy, normal-weight women (age 22 +/- 3 years). MEASUREMENTS Plasma concentrations of leptin, soluble leptin receptor protein (sOB-R), adiponectin, resistin, thyroid hormones and beta-hydroxybutyrate were determined following overnight fast before and after the 4-week reduced-calorie diet. RESULTS Subjects lost a mean of 3.4 +/- 2.1 kg in response to the reduced-calorie diet. The weight loss phase was associated with a 60.3% decrease in plasma leptin levels (P < 0.001), a 43.5% increase in sOB-R levels (P < 0.002) and a 16.2% decrease in plasma adiponectin levels (P < 0.04). There was no significant change in plasma resistin levels. CONCLUSIONS These results demonstrate that a modest decrease in energy intake sustained over several weeks may play an important role in altering levels of plasma leptin and sOB-R. The findings also provide preliminary evidence that, in contrast to previous results in obese subjects, caloric restriction with accompanying weight loss in healthy, normal-weight volunteers may lead to decreased circulating adiponectin levels. Additional studies will be needed to clarify the contribution of altered energy intake to abnormalities in cytokine levels in the eating disorders.