An Overview of Breastfeeding and Childhood Obesity

Mother breastfeeding her child. KidStock/Blend Images/Getty Images

Choosing whether or not to breastfeed her child is one of the most personal decisions a new mother will make for her newborn. When weighing the factors that contribute to that decision, it’s worth keeping in mind that the “breast is best” adage may apply to your child’s future weight as well as his or her health. After all, the benefits of breastfeeding to a child’s health are well established. These include a lower risk of sudden infant death syndrome (SIDS), ear and upper respiratory infections, pneumonia, urinary tract infections, eczema, gastroenteritis, and type 2 diabetes, and overall enhanced immune function, among others.

These are some of the reasons why the American Academy of Pediatrics recommends exclusive breastfeeding for the first six months of a baby’s life.

The Breast (Milk) Defense

Meanwhile, for mothers, the health perks of breastfeeding include a decreased risk of breast and ovarian cancer, and type 2 diabetes. Moms who breastfeed also tend to lose their pregnancy weight faster and the hormones that are released during breastfeeding help the uterus return to its normal size more quickly after childbirth. Nursing a child can also enhance the developing bond between mother and baby. 

There’s also some evidence that breastfeeding a child may help reduce his or her chances of becoming overweight. In a review of 17 studies on the subject, researchers from Germany found that one month of breastfeeding was associated with a 4 percent decreased risk of becoming overweight, and babies who were breastfed for 9 months or longer had a 32 percent lower risk of becoming overweight, compared to children who were never breastfed.

In general, the effect depends on how long a baby is breastfed and whether he or she is breastfed exclusively or has formula, too. Exclusively breastfeeding a child—as opposed to combining breastfeeding with formula feeding—appears to confer a stronger protective benefit when it comes to a baby’s weight.


The effect is so powerful that it might even override genetic influences. Here’s a real eye-opener: Researchers at Northwestern University conducted a study involving 488 pairs of siblings, one of whom was breastfed while the other wasn’t, and tracked their body mass index (BMI) into adolescence. What they found is that the siblings who were breastfed had BMIs, as teenagers, that were .39 standard deviations lower—the equivalent of more than 13 pounds lower for a 14-year-old of average height—than their formula-fed sibs did. That’s a significant difference!

What’s Behind the Weight Management Effect

While no one knows exactly how breastfeeding reduces the risk of obesity among kids, there are a few theories. One is that because breastfed babies control how much milk they consume at any given time (and when they consume it), they may become more attuned to their body’s hunger and satiety (or fullness) signals, which can help them better regulate their food intake as they get older.

Another theory is that breast milk leads to a lower concentration of insulin in the blood than formula does.

This is significant because higher insulin levels stimulate greater accumulation of fat tissue, which in turn increases the risk of weight gain and type 2 diabetes. A third theory: Breastfeeding may promote more favorable concentrations of leptin, the hormone that inhibits appetite and affects the accumulation of body fat. 

Long-Lasting Weight-Control Perks

Whatever is behind this effect, here’s the really good news: Research suggests that the weight-related protection conferred by breastfeeding doesn’t diminish over time. Rather, a breastfed child’s lower risk of becoming overweight seems to continue into the teenage years and adulthood. When viewed this way, a mother’s milk could be considered a gift that keeps on giving when it comes to a child’s ability to control his or her weight.


American Academy of Pediatrics. Breastfeeding Benefits Your Baby’s Immune System. Accessed online August 28, 2014.
American Academy of Pediatrics. Where We Stand: Breastfeeding. Accessed online August 28, 2014.
Centers for Disease Control and Prevention. Does breastfeeding reduce the risk of pediatric overweight? Accessed online August 28, 2014.
Harder T, Bergmann R, Kallischnigg G, Plagemann A. Duration of breastfeeding and risk of overweight: a meta-analysis. American Journal of Epidemiology, September 1, 2005 [Accessed online August 28, 2014]; 162(5): 397-403.
Metzger MW, McDade TW. Breastfeeding as obesity prevention in the United States: a sibling difference model. American Journal of Human Biology, May-June 2010 [Accessed online August 28, 2014]; 22(3): 291-6.

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