Predictors of body size in the first 2y of life: a high-risk study of human obesity

OBJECTIVE: To ascertain the predictors of body size at 2 y of age. DESIGN: Prospective, longitudinal study of risk factors for weight gain of infants at high or low risk of obesity by virtue of their mothers' obesity or leanness. SUBJECTS: A total of 40 infants of obese mothers and 38 infants of lean mothers, equally divided among boys and girls. METHODS: Measurement of dependent variables: weight, length and skinfold thicknesses at 3, 6, 9, 12, 18 and 24 months and percent body fat at 3, 12 and 24 months. Measurement of independent variables: average daily caloric consumption at 3, 6, 9, 12, 18 and 24 months; and, at 3 months, nutritive sucking behavior during a test meal, total energy expenditure ( TEE), sleeping energy expenditure ( SEE), estimation of nonsleeping energy expenditure ( TEE - SEE) and socioeconomic status. Parental weights and heights were obtained by self-report at the time of recruitment. Partial correlation and mixed effects linear regression analyses were performed. RESULTS: Measures of body size ( weight, length, skinfold thicknesses) and percent of body fat were almost identical between high- and low-risk groups at all times. Energy intake during six occasions over the 2 y, sucking behavior, family income and TEE predicted weight gain, controlling for body length. Parental body mass index was not associated with the child's body size during the first 2 y. During the first year, there were strong lagged correlations between energy intake and body weight and smaller correlations between protein intake and body weight. CONCLUSION: Energy intake, and not energy expenditure, was the determinant of body size in these infants at 2 y of age, as it had been at 1 y. Sucking behavior and TEE ( positively) and family income ( negatively) also contributed to body weight at 2 y. The novel finding of a lagged correlation between energy intake and body weight early in life suggests that energy intake is programmed for future growth and development.