The real link between breastfeeding and preventing obesity

Claire McCarthy, MD

Senior Faculty Editor, Harvard Health Publishing

While we know that breastfeeding has many health benefits for mothers and babies, the studies have been a bit fuzzy when it comes to the link between breastfeeding and preventing obesity in children. Some studies show a clear link, but in others that link is less clear. A new study published in the journal Pediatrics may help explain the fuzziness. It showed that what really helped prevent obesity was getting breast milk directly from the breast.

That’s not to say that drinking expressed breast milk from a bottle isn’t healthy. After all, it’s the food that was explicitly designed for infants — and in the study, babies that got breast milk from a bottle did have lower rates of obesity at 12 months. Some of that benefit is thought to be related to the microbiome that breast milk helps create. Babies who drink breast milk are more likely to have certain bacteria in their digestive tracts that help prevent obesity.

But the babies that had the lowest risk of obesity in the study were those that got only breast milk directly from the breast for the first three months of life. Why would that be?

To be able to breastfeed directly from the breast for three months, you have to be able to be with your baby constantly for three months. Mothers who can do that either have access to paid maternity leave or have enough resources to take an unpaid leave — or to stay at home with their babies and not work outside the home at all. Studies have shown that mothers who breastfeed longer are more likely to have higher incomes, more education, and private insurance.

These, then, are mothers who are also more likely to have access to and be able to afford healthy foods, to live in areas where there are safe places to exercise — and to be able to pay for sports and other forms of exercise as their children grow. It’s not just about how these babies are fed, but also about the context in which they are born and raised.

The way in which they are fed, though, is important. Babies who feed directly from the breast are less likely to be overfed. When they are full, they stop sucking, or switch to a “comfort” kind of sucking that doesn’t produce milk. When babies are fed from bottles, parents and caregivers are more likely to push them to finish the bottle; feeding becomes a bit less about appetite and more about volume and schedule.

Learning to eat only when you are hungry and stop when you are full is a really good skill when it comes to preventing obesity. That’s why the American Academy of Pediatrics has encouraged parents to learn and use “responsive feeding,” that is, responding to the cues of babies and children of both hunger and being full. The motto is, “You provide, your child decides.”

What this study helps us see is that the link between breastfeeding and obesity prevention is part of a bigger picture we need to pay attention to if we want to fight the obesity epidemic. It shows us that we need to:

  • Do everything we can to help mothers stay at home with their babies for at least three months, which will require paid maternity leaves. The United States is way behind the rest of the world in this.
  • Help all parents, regardless of how they feed their infants, learn about responsive feeding, and thus help their babies learn to eat when they are hungry and stop when they are full.
  • Understand obesity risk as part of a bigger societal issue — truly, as a social justice issue. All children need — and deserve — access to healthy foods and exercise, and there is more we can do to make this happen.


  1. Rafael Perez-Escamilla

    Thanks for writing a good balanced editorial on what has been a “controversial” topic in spite of mounting evidence that breastfeeding does offer a small but significant overall protection against the risk of childhood obesity. What the CHILD cohort study adds is that this benefit may be much stronger if breastmilk is fed from the breast instead of through a bottle – which is how many…many women are feeding expressed breastmilk in the USA. The authors provide very reasonable biological explanations from their findings making their results even more meaningful.

  2. Ann LaFontaine

    I had two kids. Went to work after two weeks, since I was self employed. Both my babies a breast fed, or fed by pumping milk while away from home. If I can do it anyone can.
    Great way to prevent obesity in new moms too.

  3. D. Thomas

    Hello. Thank you for the information in your article. I would like to say from my own experience that I breastfed 4 of my 5 children. While I would recommend it to others, I have to say the 2 of the breastfed children are overweight adults, 1 breastfed child has been obese since a young age despite being active in sports year-round, and the bottle fed child is also an obese adult and has struggled with weight since childhood. I think it is difficult to say that breastfeeding might prevent obesity when there are so many other factors such as genetics and the food offered in our markets depending where you live in the world. I still recommend breastfeeding for many of its other benefits, but if one has to bottlefeed, know that your children will be fine. I was a bottlefed baby and have not experience obesity issues or other health complications.

  4. Alexandra

    Haven’t there been any reliable studies on this made in countries with generous parental leave benefits, where you could more easily rule out the correlation breastfed=higher income=lower obesity? In Scandinavia most parent regardless of income levels are home for three months or more and most who are physically able to opt for breastfeeding.

  5. Joann Love MD

    Babies who are breast fed have a lower risk of common infections and therefore are prescribed fewer antibiotics. We know antibiotic therapy in infants and children increases the risk of obesity. So this is a second factor in avoiding obesity in children, they come through the early part of their lives with an intact micro biome, a big big plus.

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