A new study sheds light on ways to fight childhood obesity — before infants are even out of the cradle. Formula-fed babies who begin solid foods too early — before they’re 4 months old — are six times as likely to become obese by age 3, compared with babies who start on solids later, according to a study of 847 in today’s Pediatrics. About 9% of children in the study were obese by age 3.
Although the American Academy of Pediatrics recommends that parents delay introducing solid foods until ages 4 to 6 months, 26% start on solids by 4 months old, according to background information in the study. Breast-fed babies face no additional risk of obesity, regardless of when they start solids, the study says. The academy recommends that mothers breast-feed exclusively for the first six months, combining nursing with other foods for at least a year.
Doctors have long known that breast-fed infants are less likely to become overweight. Surveys show that only 75% of American babies get any breast milk, however, and half are nursed for less than four months, the study says.
A 2005 study in the Journal of the American Medical Associationestimated that switching formula-fed babies to breast milk could reduce the child obesity rate by 15% to 20%. Doctors can’t fully explain why breast-feeding is so protective, say authors Susanna Huh and Sheryl Rifas-Shiman, of Children’s Hospital Boston. But it’s possible that breast-feeding mothers may stop nursing when a baby seems full, rather than encouraging an infant to finish a bottle, they say.
Experts note that the study has limitations.
It’s possible that the children’s obesity is more closely related to their parents’ educational levels than their feeding practices, given that people with less education may not be informed about the healthiest time to start solid foods, says Atlanta pediatrician Jennifer Shu. Obesity is more common among people with less education.
One positive message from the study is that parents and pediatricians may be able to help reduce obesity simply by delaying solids until at least age 4 months, Huh and Rifas-Shiman say.