Breastfeeding Reducing Childhood Obesity: Fact, Fiction or Sometimes?

Over the past 3 decades, an increasing number of studies and reviews have examined the relationship of breastfeeding and childhood obesity. The authors of Agency for Healthcare Research and Quality’s (AHRQ) Evidence Report on Breastfeeding meta-analysis concluded that children who were breastfed for at least 3 months were less likely to be obese than those never breastfed, taking into account multiple confounding factors.¹ The duration of breastfeeding was found to be inversely related to the risk of being overweight; each month of breastfeeding being associated with a 4% reduction in risk. A WHO meta-analysis from 2007 also concluded that longer breastfeeding (typically durations of 3 to 9 months), in comparison to no breastfeeding, was associated with lower rates of obesity.² The Framingham Offspring study noted a relationship of breastfeeding and a lower BMI in adults.³ A sibling difference model study showed that the breastfed siblings weighed 13 pounds less than formula fed siblings at a mean age of 14 and were less likely to reach BMI obesity threshold.⁴ Based upon these studies, the promotion of breastfeeding to prevent obesity has been recommended by the CDC, the Institute of Medicine, and the Surgeon General.

However, there are, however, other important studies that failed to find a relationship. The PROBIT study, the only randomized trial of breastfeeding in term infants, randomized an intervention to promote increased duration and exclusivity of breastfeeding in Belarus and found no significant differences in BMI, percent body fat, and obesity between the experimental and control group children at 11.5 years of age.⁵ The “discordant sibling study” looked at data obtained from the National Longitudinal Survey of Youth study and found that breastfeeding was not associated with significant improvements in childhood obesity when siblings who were fed differently during infancy, one breastfed, the other bottle fed, were compared.⁶

So how are we to interpret these conflicting studies? My opinion has been that, as the etiology of obesity is multifactorial, breastfeeding can play an important role in its prevention, but is unlikely to entirely prevent it. The limitation of most of these studies is that they look at breastfeeding alone. Future studies need to focus on the role of multiple modifiable factors on these conditions.⁷