Influence of preweaning food intake on body composition of young adult baboons.

The hypothesis that infant overnutrition increases fat cell number and promotes obesity in the young adult primate was tested. Newborn baboons were fed similar volumes of Similac formulas with caloric densities of 40.5 (underfed, n = 8), 67.5 (normally fed, n = 12), and 94.5 (overfed, n = 12) kcal/100 g formula until 4 mo of age. Afterwards all baboons were fed the same diet until they were young adults. At 5 yr of age body composition, mean fat cell size, and total fat cell number were measured. Infant food intake did not significantly influence body composition or fat cell number in the 5-yr-old male baboons. Five-year-old female baboons, overfed as infants, had significantly greater body fat mass, percent of body mass that was fat, and mean fat cell volume compared with females that were underfed or normally fed as infants. There was no difference in total fat cell number between the obese baboons that were overfed as infants and the lean baboons that were underfed or normally fed as infants. Fat cell number was not associated with body fat content; males had more fat cells than did females. These results demonstrate that infant overnutrition in a primate species promotes obesity in young adult females by increasing primarily fat cell size and not fat cell number.