Breastfeeding reduces risk of obesity - Bulletins: news about pregnancy, birth, and parenting

SIXTY-FIVE PERCENT OF ADULTS IN THE US ARE OVERweight or obese. It's no wonder that the Centers for Disease Control has named four priorities for fighting the obesity epidemic: reduced TV viewing, more physical activity, increased consumption of fruits and vegetables, and--surprise--higher rates of breastfeeding.

Adding to the growing body of evidence supporting the health benefits of breastfeeding, a conclusive and significant link has been discovered between breastfeeding in infancy and obesity later in life. Researchers at the University of California, Davis, analyzed several years' worth of breastfeeding studies that included tens of thousands of children from seven countries and found that those who were breastfed were 30 percent less likely to be obese. Harvard researchers surveyed about 15,000 children, ages 9 to 14, and found that those who were fed only or mostly breastmilk during their first six months of life were 22 percent less likely to be overweight during adolescence than those who were fed only or mostly formula. (Researchers tried to control for mothers' weights and other socioeconomic factors that could also explain the results.) In addition, the risk of becoming overweight went down with each additional month a child was breastfed.

That's not all. The longer babies were exclusively breastfed before switching to formula or food, the lower their chances of starting school overweight or obese. One study, which tracked 9,357 children in Bavaria, found that infants given only breastmilk until they were three to five months old were more than a third less likely to be obese by age five or six than babies given only formula from the start. Those exclusively breastfed for six months to a year fared even better: they were 43 percent less likely to be obese. Breastfeeding beyond a child's first birthday was better still, decreasing a baby's risk of obesity by 72 percent.

Even some breastmilk proved to be better than none. Children who were breastfed for only the first month or two of their lives were 10 percent less likely to be obese by the time they entered elementary school, the risk continuing to diminish the longer breastfeeding went on.

What is it about breastmilk that can have such a preventive impact on weight years later? There appear to be many answers to that question. Breastfed babies have higher levels of leptin, a hormone that helps to regulate appetite. They are better able to program themselves to stop eating when they are full, learning to self-regulate their caloric intake over time. Bottle-fed babies are often overfed because parents encourage babies to empty the entire bottle. This overfeeding can increase the number of permanent fat cells. In addition, babies fed formula during the critical early weeks experience changes in their pancreatic islets that lead to overproduction of insulin and adult obesity. Formula is made with sucrose (essentially white table sugar), which is much sweeter than lactose, the sugar found in breastmilk. So formula-fed babies develop a natural affinity for sweet, fatty foods.

Experts caution that breastfeeding is not the sole answer to the epidemic of childhood obesity. The clearest predictor of which children will grow up too fat remains genetic: Children with fat parents are five times more likely to be overweight. And kids who eat unhealthy diets and do not exercise will become overweight no matter what shape their parents are in. Still, this new research makes the list of reasons to breastfeed just a little longer.

REFERENCES

Department of Health and Human Services, Centers for Disease Control and Prevention. "Resource Guide for Nutrition and Physical Activity Interventions to Prevent Obesity and Other Chronic Diseases," 32-36. www.cdc.gov/nccdphp/dnpa/obesityprevention.htm.

Hediger, M. L., et al. "Association between Infant Breastfeeding and Overweight in Young Children." The Journal of the American Medical Association 285 (2001): 2453-2460.

Hellmich, Nanci. "Breastfeeding May Prevent Obesity in Kids." USA Today (May 15, 2001). www.usatoday.com/news/health/2001-05-15-breastfeeding.htm.

Ross, Emma. "Breast-feeding Babies Reduces Childhood Obesity, Study Says." Milwaukee Journal Sentinel (July 16, 1999). www.jsonline.com/alive/family/jul99/breast-feeding-obesit071599.asp.

Severson, Kim. "Breast Milk May Help Control Growing Appetite." San Francisco Chronicle (January 8, 2003). http://sfgate.com/cgi bin/article.cgi?f=/c/a/2003/01/08/MN194123.DTL.

Von Kries, R., et al. "Breastfeeding and Obesity: Cross Sectional Study." Institute for Social Paediatrics and Adolescent Medicine, Ludwig Maximilians University, Heiglhofstrasse 63, D-81377 Munich, Germany. www.ncbi.nlm.nih.gov/entrez /query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10406746&dopt=Abstract.

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