Objective: To investigate to what extent serum leptin concentrations in obese humans are influenced by a history of weight cycling.
Design: Cross-sectional study on serum leptin concentrations and body composition in a cohort of obese subjects in whom a retrospective recall of weight and diet history was made.
Subjects: One hundred and twenty-eight obese patients (89 females and 39 males), aged 18-61 y, 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 overweight 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 significantly correlated with weight, waist-hip ratio, percentage body fat, maximal percentage weight loss in a single diet episode, cumulative percentage weight loss in all diet episodes, cumulative weight regained in all diet episodes, but not with the number of diet episodes. All correlations related to anthropometric and body composition parameters were stronger for men, compared to women, although the male subgroup was smaller. On the contrary, there was a strong positive correlation between weight cycling parameters and serum leptin in women but not in men. Leptin concentrations were significantly higher in patients who were overweight at puberty than in those who were not overweight at puberty. After correction for percentage body fat, presence of overweight at puberty did not correlate any longer with leptin concentrations in either gender. In women, cumulative percentage weight loss in all diet episodes contributed an additional 5% to the variance of serum leptin in the overall model.
Conclusion: The positive correlation between weight cycling and leptin concentration in obesity is mainly accounted for the higher percentage body fat in obese weight cyclers, although in women weight cycling per se independently contributes to the variance of serum leptin.