Early nutrition is recognized as a target for the effective prevention of childhood obesity. Protein intake was associated with more rapid weight gain during infancy—a known risk factor for later obesity. We tested whether the reduction of protein in infant formula reduces body mass index (BMI; in kg/m2) and the prevalence of obesity at 6 y of age. The Childhood Obesity Project was conducted as a European multicenter, double-blind, randomized clinical trial that enrolled healthy infants born between October 2002 and July 2004. Formula-fed infants (n = 1090) were randomly assigned to receive higher protein (HP)– or lower protein (LP)–content formula (within recommended amounts) in the first year of life; breastfed infants (n = 588) were enrolled as an observational reference group. We measured the weight and height of 448 (41%) formula-fed children at 6 y of age. BMI was the primary outcome. HP children had a significantly higher BMI (by 0.51; 95% CI: 0.13, 0.90; P = 0.009) at 6 y of age. The risk of becoming obese in the HP group was 2.43 (95% CI: 1.12, 5.27; P = 0.024) times that in the LP group. There was a tendency for a higher weight in HP children (0.67 kg; 95% CI: -0.04, 1.39 kg; P = 0.064) but no difference in height between the intervention groups. Anthropometric measurements were similar in the LP and breastfed groups. Infant formula with a lower protein content reduces BMI and obesity risk at school age. Avoidance of infant foods that provide excessive protein intakes could contribute to a reduction in childhood obesity. This trial was registered at clinicaltrials.gov as NCT00338689.

Lower protein content in infant formula reduces BMI and obesity risk at school age: follow-up of a randomized trial