Assessing risk factors for obesity between childhood and adolescence: I. Birth weight, childhood adiposity, parental obesity, insulin, and leptin

Objective. To assess the effects of body weight, body composition, parental obesity, and metabolic variables on the development of obesity in a large cohort of 5-year-old Native American children with a high propensity for obesity. Methods. During the summer months of 1992 to 1995 and again 5 years later, 138 (65 boys and 73 girls) 5-year-old Pima Indian children were studied. Height; weight; body composition; parental obesity; and fasting plasma insulin, glucose, and leptin concentrations were determined at baseline and follow-up. Linear regression models were used to assess the effect of the baseline variables on the development of obesity. Results. At both 5 and 10 years of age, Pima Indian children were heavier and fatter than an age- and gender-matched reference population. All anthropometric and metabolic variables tracked strongly from 5 to 10 years of age (r greater than or equal to 0.70). The most significant determinant of percentage of body fat at 10 years of age was percentage of body fat at 5 years of age (R-2 = 0.53). The combined effect of high maternal body mass index, elevated fasting plasma leptin concentrations, and low fasting plasma insulin concentrations at baseline explained an additional 4% of the total variance in adiposity at follow-up. Conclusions. Although parental obesity and metabolic variables such as insulinemia and leptinemia at baseline account for a small percentage of the variance in adiposity at follow-up, early childhood obesity is the dominant predictor of obesity 5 years later. These results suggest that strategies to prevent childhood obesity must be initiated at a very early age.