The results of the study showed that formula-fed babies who begin solid foods before they're 4 months old are six times more likely to become obese by the age of 3, compared to breast-fed babies.
Meantime, breast-fed babies faced no additional risk of obesity regardless of when they started solids.
It was unknown why breast feeding is so protective of obesity.
Experts speculate that breast feeding moms may stop nursing when a baby seems full, rather than encouraging an infant to finish a bottle.
