Energy utilization of breast-fed and formula-fed infants.

Breast-fed and formula-fed infants (n = 65) were studied at 1 and 4 mo of age to elucidate differences in energy utilization between feeding groups. Gross energy intake at 1 mo was comparable between groups but was statistically different at 4 mo. Weight, length, and weight gain were not different between groups. Energy expenditure 0-4 h postprandially did not differ between feeding groups. Sleeping metabolic rates (SMRs) were not different but minimal observable energy expenditures standardized by weight were lower among 4-mo-old breast-fed infants (p less than 0.03). No differences were found between feeding groups in thermic effect of feeding (TEF). Activity patterns revealed that breast-fed infants slept less than formula-fed infants (p less than 0.04). Disparities in energy intake observed between breast-fed and formula-fed infants at 4 mo of age did not result in statistically significant differences in growth rate, SMR, or TEF.