Contribution of weight cycling to serum leptin in human obesity

OBJECTIVE: To investigate to what extent serum leptin concentrations in obe se humans are influenced by a history of weight cycling. DESIGN: Cross-sectional study on serum leptin concentrations and body compo sition in a cohort of obese subjects in whom a retrospective recall of weig ht and diet history was made. SUBJECTS: One hundred and twenty-eight obese patients (89 females and 39 ma les), aged 18-61y, body mass index (BMI) 31.2 - 63.4 kg/m(2.) MEASUREMENTS: Serum leptin; various fatness and fat distribution parameters (by anthropometry and bioelectrical impedance analysis); history of overwe ight at puberty; number, magnitude and timing of previous diet episodes and of consequent weight regain by interview. RESULTS: By univariate analysis, serum leptin concentrations were significa ntly correlated with weight, waist-hip ratio, percentage body fat, maximal percentage weight loss in a single diet episode, cumulative percentage weig ht loss in all diet episodes, cumulative weight regained in all diet episod es, but not with the number of diet episodes. All correlations related to a nthropometric and body composition parameters were stronger for men, compar ed to women, although the male subgroup was smaller. On the contrary, there was a strong positive correlation between weight cycling parameters and se rum leptin in women but not in men. Leptin concentrations were significantl y higher in patients who were overweight at puberty than in those who were not overweight at puberty. After correction for percentage body fat, presen ce of overweight at puberty did not correlate any longer with leptin concen trations in either gender. In women, cumulative percentage weight loss in a ll diet episodes contributed an additional 5% to the variance of serum lept in in the overall model. CONCLUSION: The positive correlation between weight cycling and leptin conc entration in obesity is mainly accounted for the higher percentage body fat in obese weight cyclers, although in women weight cycling per se independe ntly contributes to the variance of serum leptin.