Influence of serum leptin on weight and body fat growth in children at high risk for adult obesity.

Objective: Our objective was to examine serum leptin prospectively as a predictor of weight and body fat growth in children at high risk for adult obesity. We hypothesized that leptin measurements would be positively associated with increased growth of adipose tissue because children with high baseline leptin for their body fat mass have greater leptin resistance and thus would have greater susceptibility to weight gain. Methods: Children ages 6 - 12 yr at high risk for adult obesity because of early-onset childhood overweight and/or parental overweight were recruited from 1996 - 2004. Growth in body mass index ( BMI) was studied in 197 children, and growth in total body fat mass was examined in 149 children over an average follow-up interval of 4.4 yr ( range, 1 - 8 yr). Longitudinal analyses accounted for sex, race, socioeconomic status, initial body composition, age, skeletal age, and physical activity and included all available interim visits for each individual so that a total of 982 subject visits were included in the analysis. Results: At baseline, 43% of children studied were overweight ( BMI >= 95th percentile); during follow-up, an additional 14% became overweight. Independent of initial body composition, baseline leptin was a statistically significant positive predictor of increased BMI ( P = 0.0147) and increased total body fat mass ( P < 0.007). Conclusions: High serum leptin, independent of body fat, may be an indicator of increased leptin resistance, which predisposes children at high risk for adult obesity to somewhat greater growth in weight and body fat during childhood.