Anthropometry and Body Composition in Childhood: Follow-Up of a Randomised, Double-Blinded Controlled Trial With a Modified, Low-Protein Infant Formula During Infancy

Introduction: Formula feeding is associated with an increased obesity risk compared to breastfeeding, possibly due to its higher protein content. We aimed to investigate the influence of feeding a modified, low-protein infant formula during the first 6 months of life on growth and body composition at 6 years. Methods: Healthy term-born infants were randomised to receive a low-protein (mLP) infant formula with modified amino acid composition (n = 90; 1.7 g protein/100 kcal) or a control infant formula (CTRL) (n = 88; 2.1 g protein/100 kcal) up to 6 months. A breastfed (BF, n = 67) group served as a reference. At 6 years, anthropometry and body composition (air-displacement plethysmography) were measured. Results: A total of 106 infants were measured at 6y follow-up, (n = 39 mLP; n = 33 CTRL; n = 34 BF). No significant differences were observed in mean weight, length, BMI, or fat mass percentage. However, the mean fat-free mass was lower in the mLP compared to the CTRL group (−1240 g; 95% CI: −1889 to −591, p < 0.001). Moreover, both formula groups had a higher absolute fat mass when compared to the breastfed group (p = 0.01). Conclusions: Feeding a mLP formula during early life did not have beneficial effects on body composition in a subset of infants studied at age 6 year.