Does breastfeeding protect from growth acceleration and later obesity?

Nutrition in infancy has been suggested to have a major influence or program the long-term tendency to obesity. Breastfeeding, in particular, appears to protect against the development of later obesity, a conclusion supported by data from four systematic reviews and evidence that a longer duration of breastfeeding has greater protective effects. The size of the effect (up to a 20% reduction in obesity risk) although modest has important implications for public health. The mechanisms involved, although poorly understood, probably include the benefits of relative undernutrition and slower growth associated with breast rather than formula feeding - the growth acceleration hypothesis. This hypothesis is now supported by data from animal studies and two recent systematic reviews, which suggest an association between faster growth in infancy and later obesity in both richer and low-income countries and for both faster weight and length gain. The present review considers the evidence for a role of early growth and breastfeeding in the programming of obesity and the underlying mechanisms involved.