Breastfeeding and Later Obesity
Study Fails to Find Protective Benefit From Breastfeeding for Adult Overweight
April 24, 2007 -- Breastfed babies are just as likely to grow up to be
overweight adults as babies who are bottle fed, new research shows.
Results from a study involving more than 35,000 female nurses seem to
contradict earlier research, which prompted government health officials to
recommend breastfeeding as a strategy for reducing childhood obesity.
There was a suggestion of a protective effect during early childhood, but no
link was seen between breastfeeding and body weight after age 5, says Harvard
Medical School associate professor Karin B Michels, PhD.
“Even if breastfeeding is protective very early in life, this does not
appear to carry through to adolescence and adulthood,” Michels tells WebMD. “We
certainly encourage breastfeeding, which has many positive consequences for
both mother and child. But it should not be promoted as a solution for either
the childhood or adult obesity epidemic.”
12.5 Million Overweight Kids
The number of overweight children and teens has more than tripled in the
United States since 1980, according to the CDC.
According to CDC figures from 2003-2004, 12.5 million kids between ages 2
and 19 are overweight.
Though it is clear that breastfed infants tend to gain weight more slowly
during the first year of life, the link between breastfeeding and body weight
later on is much more uncertain, Michels says.
The latest study is the first attempt to examine the residual impact of
breastfeeding on body weight until age 40.
A total of 35,526 female nurses participating in the larger Nurses Health
Study II were followed from 1989 until 2001, and their mothers were surveyed to
determine if the nurses where breastfed during infancy and, if so, for how
Nurses exclusively breastfed during the first six months of life were no
less likely to be overweight or obese during adulthood as those who were bottle
fed during infancy.
A slight association was seen between infant breastfeeding and lower body
weight up until age 5, but it was not significant, Michels says.
The study appears in the latest online issue of the International Journal
‘Jury Still Out’
Michels says public health messages that encourage breastfeeding as a
strategy for reducing later obesity overstate the case for a protective
But the chief of the nutrition branch for the CDC disagrees.
Though there is little evidence that protection lasts until adulthood,
Laurence Grummer-Strawn, PhD, says the research as a whole continues to support
a protective role for breastfeeding, at least in early life.
“The best evidence we have indicates that the [protective] effect probably
diminishes over time, and that is what this study shows,” he tells WebMD. “It
is not very surprising that the evidence would fail to show a benefit for
breastfeeding 40 years later.”
Women in the U.S. who breastfeed tend to be better educated and more
economically advantaged than women who choose not to breastfeed their babies.
They also tend to lead healthier lifestyles, with the assumption that they
promote healthier behaviors in their children.
Grummer-Strawn acknowledges that these socioeconomic influences may explain
the link between breastfeeding and lower childhood body weight. But even if
this proves to be the case, there are still plenty of good reasons to
Among other things, breastfed babies have a lower risk for developing ear
infections, respiratory illness, and diarrhea early in life.
“The jury is still out on whether there is a causal relationship (between
breastfeeding and childhood body weight),” Grummer-Strawn says. “The CDC
continues to promote breastfeeding for a number of health reasons, including
the possible prevention of overweight in children.”