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Breastfeeding and the Fast-Gaining Baby

Rebecca Butler
La Plata MD USA
From: LEAVEN, Vol. 42 No. 3, July-August-September 2006, pp. 54-55

Obesity is a new "hot topic," especially in the United States, and everyone is interested in ways to prevent and cure it. Recent studies have emphasized the role of breastfeeding in protecting against obesity. But what happens when a breastfed baby gets "too fat"?

According to the BREASTFEEDING ANSWER BOOK, "Average weight gain for the first three to four months is about six ounces (170 grams) per week" (Mohrbacher and Stock 2003). This average works for most babies, but what about the baby who gains double this, or more? Is his mother starting him on bad eating habits that will follow him into adulthood?

Recently, I worked with three mothers whose babies were gaining an average of one pound per week at around six weeks of age. All were healthy full-term babies who had gained well from the very beginning. Two mothers were exclusively breastfeeding, the other was combining formula and breastfeeding. Their pediatrician's advice varied from offering one ounce of water before every feeding, to decreasing feedings, to "don't worry about it." These women were not happy with the advice given to them, and all were worried that their babies would have lifetime weight issues.

There is "no evidence that a baby who gains rapidly on human milk will have weight problems as an older child, an adolescent, or an adult" (Mohrbacher and Stock 2003). I reassured all the mothers that responding to their baby's needs was both appropriate and beneficial. I also encouraged the mother who was using formula to try to rely only on human milk. The mothers were relieved, but I was uncertain. Can we really make a blanket statement that it doesn't matter how fast a breastfed baby gains? Secondly, how can we support mothers of fast-growing babies in a manner that would be both educational as well as supportive of their concerns for their baby's long-term health?

The research clearly demonstrates that breastfed babies are less likely to become obese. In the past few years, multiple large-scale studies have addressed the relationship between breastfeeding and obesity. A review of the literature published in May 2005 Pediatrics concludes that breastfeeding protects against obesity in later life (Owen et al. 2005). Some studies have considered the duration of breastfeeding and were able to demonstrate a dose-response effect, with babies less likely to become obese the longer they were breastfed (von Kries et al. 1999; Harder et al. 2005).

On the other hand, an overview of recent literature found no research to support putting breastfed babies on "diets" (Dewey 2003). Giving a breastfed baby water in the early months is, in fact, detrimental since the water displaces the high-calorie, high-fat human milk, which is necessary for optimal brain growth and development. Any substitute for human milk also includes the risk of contamination as well as the possibility that it will interfere with the delicate balance of the breastfeeding relationship. Research has demonstrated that breastfed babies who gain very fast in the first six months become leaner than formula-fed babies after the first six months (Dewey et al. 1993).

Opinions about how breastfeeding protects babies from obesity vary. One suggestion is that the breastfed baby better regulates his intake according to his needs. A mother with an oversupply may wonder if her baby can still self-regulate. This is a good question, since some babies appear to be overwhelmed by the mother's supply. Supporting the mother to reduce her supply to better meet the baby's needs is appropriate (Mohrbacher and Stock 2003). It is also worth mentioning to the mother, however, that babies regulate their needs depending on not only the number of ounces but the fat content of the milk. "Infants whose mothers produce higher-fat milk generally consume less milk, presumably reflecting self-regulation to match their energy needs" (Dewey 2003). Another hypothesis about the protective effect of breastfeeding is the composition of the milk itself. Breastfeeding may influence baby's blood plasma insulin levels and leptin (a protein hormone) metabolism both of which impact weight gain (Dewey 2003). A study that compares breastfed babies fed solely at the breast and those who receive only expressed human milk might help to clarify how breastfeeding protects against obesity. If infant demand is the most significant factor, then the babies who are fed expressed human milk by bottle would not receive the same protection from obesity. On the other hand, if the composition of the milk is more significant, then babies fed human milk by bottle should be equally protected from obesity.

Of course, genetics and family food practices play a large role in determining later obesity. Breastfeeding may mitigate the factors of genetics and social and cultural food practices, but it cannot eliminate them. Some breastfed babies will still be overweight children and adults. Parents can help by exclusively breastfeeding, offering healthy solid foods when the baby shows signs of readiness, and by demonstrating healthy eating and exercise habits.

A "fat" breastfeeding baby is the ideal for some and a source of concern for others. The societal focus on preventing obesity can lead some mothers and physicians to panic when they see a baby gaining very quickly in the first few months. Some mothers just need reassurance that their babies are individuals, with their own individual growth patterns, and that human milk is the perfect food for them to grow on. Others will appreciate knowing that there is no evidence to support "dieting" or substituting other foods or liquids for human milk to reduce weight gain.


Dewey, K.G. Is breastfeeding protective against child obesity? J Hum Lact 2003; 19:9-18.

Dewey, K.G., Heinig, M.J., Nommsen, L.A. et al. Breastfed infants are leaner than formula-fed infants at 1 year of age: the DARLING study. AM J Clin Nutr 1993; 57:140-45.

Harder, T., Bergmann, R., Kallischnigg, G. et al. Duration of breastfeeding and risk of overweight: A meta-analysis. Am J Epidemiol 2005; 162(5):397-403.

Von Kries, R., Koltezko, B., Sauerwald, T. et al. Breast feeding and obesity: Cross sectional study. BMJ 1999; 319:147-50.

Mohrbacher, N. and Stock, J. THE BREASTFEEDING ANSWER BOOK. Schaumburg, Illinois: LLLI, 2003; 148, 174, 116-17, 126-27.

Owen, C.G., Martin, R.M., Whincup, P.H. et al. Effect of infant feeding on the risk of obesity across the life course: A quantitative review of published evidence. Pediatrics 2005; 115(5):1367-77.

The Fast-Gaining Breastfed Baby
Facts and Suggestions to Share with Mothers

There is no evidence that a fast-gaining breastfed baby will become an overweight child or adult. In fact, research clearly indicates that breastfeeding protects against obesity later in life. So, how can a mother help her baby gain weight in a healthy manner?

  1. Exclusively breastfeed for the first six months. Exclusive breastfeeding means that a baby gets only the perfect food. Human milk has no additives, fillers, or empty calories.
  2. Wait until about six months to offer solid foods. Early introduction of solid foods can increase obesity as well as allergies. The American Academy of Pediatrics changed their recommendations several years ago. They clearly state that solids should wait until six months.
  3. When offering solid foods, start with very small amounts and offer them after breastfeeding. Breastfeeding should still be the basis of a baby's diet through the first year. Solids are an addition, not a substitute.
  4. If a baby is fed human milk in a bottle, pace the feedings so that the baby eats slowly and has control over the flow of milk. Take frequent breaks, allowing the baby to take a breath and begin to register his or her level of satiety. Resist the temptation to coax the baby to finish the bottle or just take a little more.
  5. If a baby may be overeating because the mother has too much milk, a La Leche League Leader or a lactation consultant can help a mother learn how to manage her supply.
  6. Remember, genetics play a big role in growth patterns. How quickly did other children gain? Were baby's mother or father big babies? No matter what the child's genetic background, however, breastfeeding gives him or her the best start.
  7. Rarely, some health conditions can lead to excessive weight gain. Mothers should speak with a health care provider about any health concerns.
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