Breastfeeding and Risk of Obesity in Adulthood

A Longitudinal Study of Infant Feeding and Obesity Throughout the Life Course

A Harvard research study, published in the April 2007 edition of International Journal of Obesity, found that women who were breastfed did not have lower incidence of overweight or obesity in adulthood when compared to women who were not breastfed.  Researchers acknowledge that breastfeeding promotes the health of both mother and child but concluded, “it is unlikely to play an important role in controlling the obesity epidemic.”  This conclusion is based on data collected on 35,526 women participating in the Nurse’s Health Study II (NHS).  Information on infant feeding method was provided by the mothers of the NHS participants and was used to evaluate the relationship between infant feeding and the development of overweight and obesity throughout life.  To date, the Harvard NHS study is the largest study examining breastfeeding and its influence on adult weight status.  In addition to its large sample size, another strength of the study is the repeated measure of body mass index (BMI) during adult life.

Further, the study finds that exclusive breastfeeding (for at least six months) is associated with leaner body shape at five years; however this association does not persist into adolescence or adulthood.  The findings of this study contradict conclusions of previous epidemiologic studies that report a modest protective effect of breastfeeding on the development of adult overweight and obesity.  When asked about these earlier studies, the lead researcher, Dr. Michels, on the Harvard study concluded, “many of those [previous] studies failed to properly account for socioeconomic factors that also may have had an influence [on adult weight].”  

Michels KB et al.  A longitudinal study of infant feeding and obesity throughout life course. International Journal of Obesity.  2007; Jul. 31(7): 1078-85.

http://www.nature.com/ijo/journal/v31/n7/full/0803622a.html