Study Links Exclusive Breastfeeding to Reduction in Obesity

woman breastfeeding her baby

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Key Takeaways

  • Exclusive breastfeeding for the first six months of life can lead to a lower BMI in kids genetically predisposed to obesity.
  • Breastfeeding allows babies to control their intake and helps the brain learn to regulate hunger cues.
  • There are many other lifestyle choices that can also positively influence BMI.

If you’re planning on breastfeeding your baby, you’re certainly not alone. During pregnancy, the overwhelming majority of moms plan to breastfeed after their baby is born. And while the 2018 Breastfeeding Report Card published by the Centers for Disease Control and Prevention found that more than 83% of moms started off breastfeeding their babies, only a meager 25% were exclusively breastfed by the time they were six months old.

But a new study finds that exclusive breastfeeding of children that are genetically susceptible to obesity may have a beneficial effect on their body mass index later in life. 

Body Mass Index (BMI) is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age.

Despite being a flawed measure, BMI is widely used today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.

Study Findings

The study, which was conducted on a group of 5,266 children, found that exclusively breastfeeding a baby for the first five months of life had a “substantial effect in decreasing BMI among children at higher genetic risks.” The bad news, however, is that babies who were exclusively breastfed for the first three months of life, or were mixed fed (fed a combination of formula and breastmilk) did not enjoy the same protective benefits.

With the majority of maternity leaves in the US coming to an end around a baby’s third month of life, moms may need greater workplace support to continue breastfeeding in an attempt to hit this critical milestone. 

Childhood Obesity in America

The latest findings by the CDC indicate that more than 13 million kids in the US are obese, which is defined as having a BMI at or above the ninety-fifth percentile among other kids of the same age and gender. Obesity, even in childhood, can lead to life-threatening conditions like diabetes and heart disease. 

Experts point to the prevalence of processed foods, increased amount of time spent playing video games or watching TV, and obesity among parents as some of the top causes of childhood obesity.

While overweight and obese kids are often dealing with several contributing factors, one of the leading causes of childhood obesity is simply a child’s genetics.

Hannah Gentile, a pediatric nutritionist and positive psychology practitioner and owner of the website Empowered Mother says, “If close family members like Mom, Dad, siblings or grandparents are overweight or obese or have struggled with weight management, that's a good hint that baby will have a similar genetic susceptibility.” 

Of the many initiatives set forth in the United States to curb childhood obesity, breastfeeding is one that can start at day one of life, and set your baby up for a lifetime of healthy habits. And there’s a chance it can help keep your child’s BMI in check, even if there is a genetic component present in your family. 

Why Does Breastfeeding Cut Down on Obesity Rates?

At first, the connection between exclusive breastfeeding and reduced obesity might seem fuzzy at best. But there are two main reasons why babies who only breastfeed might have a lower BMI later in life.

First, says Gentile, “breastmilk positively influences gut bacteria. Basically, it supports the growth of healthy bacteria living within all of our digestive systems." These gut bacteria are partially responsible for things like energy metabolism, gene functioning, and immune system function.

Hannah Gentile, pediatric nutritionist

Having a healthy gut microbiome (the mix of bacteria, viruses, and fungi living in our digestive system) seems to influence our weight as we grow up.

— Hannah Gentile, pediatric nutritionist

The second way exclusive breastfeeding can lead to lower BMI later in life has less to do with chemistry and more to do with mechanics. If you think about how breastfeeding works, it’s clear that your baby is in charge of how much he eats, and when. The baby eats on demand, and over time, the amount of milk that’s produced perfectly aligns with the baby’s demand.

“When a baby is bottle-fed, parents often feel compelled to have the baby ‘finish’ the bottle, even if the amount supplied was more than the baby needed. This can essentially provide feedback to the baby's body that they should keep eating even if they aren't hungry,” says Aubrey Phelps, MS, RDN, LDN, IFNCP, PPCES, Functional Perinatal and Pediatric Nutritionist.

What Can Parents Do to Curb Obesity in Genetically Predisposed Children?

If there’s any good news here, it’s that there are certainly plenty of other things you can do to prevent obesity in your little ones, even if you and your partner struggle with weight issues, and even if you don’t exclusively breastfeed.

According to Phelps, many of her recommendations are the same things anyone should do, regardless of weight concerns. Here are some things you can put into practice to give your kids the best start possible when it comes to lifelong health. 

  • Be a role model for healthy eating. Incorporate plenty of fresh fruit and vegetables into your family’s diet. Make it fun by allowing your kids to choose a few recipes to try. 
  • Limit processed, high sugar, and saturated fat foods. With high levels of salt, sugar, and fat, these foods are almost always the culprit behind childhood obesity.
  • Get kids active. Get them involved in sports at a young age, and show an interest in their sport. Do family activities together such as a family bike ride, walk places where you can, and set up fun physical activity games at home. 
  • Don't make a fuss about food. Food should not be used as a reward. Your time, or a fun activity for the kids, should be rewards. Food is for nourishment, not punishment.

What This Means For You

In short, there’s no reason to assume that if you’re unable or simply don’t want to breastfeed exclusively, your little one’s fate is sealed when it comes to lifelong weight gain. Much more impactful are the everyday choices you make for your family, such as exercise and encouraging healthy eating choices.

But if you find yourself in a position where you’re able to exclusively breastfeed for longer than the national average, know that your baby will enjoy many benefits—one of which may be a healthier BMI later in life. 

Learn More

Exclusive Breastfeeding to Reduce the Risk of Childhood Obesity (WHO)

The Real Link Between Breastfeeding and Preventing Obesity (Harvard Health)

3 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. CDC. Breastfeeding report card.

  2. Wu Y, Lye S, Dennis CL, Briollais L. Exclusive breastfeeding can attenuate body-mass-index increase among genetically susceptible children: A longitudinal study from the ALSPAC cohortPLoS Genet. 2020;16(6):e1008790. doi:10.1371/journal.pgen.1008790

  3. CDC. Childhood obesity facts.

By Christin Perry
Christin Perry is a freelance writer and editor. Her work has been published in The Bump, The Knot, Scary Mommy, LittleThings, Parents, Qeepsake, and more. She has experience writing email marketing campaigns, website copy, and SEO-optimized content. Christin is also a mom of three.