Serum leptin and weight gain over 8 years in African American and Caucasian young adults

Objective: There is considerable interest in how to prevent weight gain in adulthood. Leptin, a peptide hormone expressed in adipose tissue, is believ ed to signal the central nervous system about the level of body fat stores, and thereby may control appetite. Little information exists on whether the serum leptin concentration influences long-term weight changes in the free -living population. Research Methods and Procedures: From an ongoing cohort study of young Afri can American and white adults, we selected a sample of participants (n=492) , stratified on sex, race, and weight changes over 8 years. Serum leptin wa s measured on stored specimens using a radioimmunoassay. Weight change was modeled in relation to baseline leptin concentrations. Results: Cross-sectionally, leptin concentration was associated positively with body mass index, negatively with physical activity level, and was high er in women than men. These variables explained 72% of the variance in seru m leptin. Over the 8 years, the sample gained an average of 7.8 kg (standar d deviation = 10.8). There was no evidence that 8-year weight change was as sociated with initial leptin concentration: 8-year weight change was only 0 .5 kg less (95% confidence interval = -1.8 to 0.8, p = 0.47) per each 10 ng /mL increment (approximately one standard deviation) of baseline leptin. In contrast, leptin change correlated highly (r = 0.62) with weight change. Discussion: Our data corroborate evidence that adiposity determines leptin levels but do not support the hypothesis that leptin deficiency plays an im portant role in obesity in the general population.