Infants who gain weight rapidly in their first eight days may risk being overweight as young adults. Researchers at the Children’s Hospital of Philadelphia studied 653 subjects aged 20 to 32 years, of whom nearly one-third were overweight. All had been bottle-fed as part of an infant-formula study. For each 100 g (3.5-oz.) gained in that first week, the risk of being overweight two or three decades later increased by almost a third.
It may be that babies “programmed” to eat too much as newborns may eat too much later. Or perhaps some had a genetic predisposition to be heavy, which came out in early eating patterns. Breastfeeding has been linked to slower infant weight gain and less obesity in adolescence.