For new mothers trying to lose those extra pounds, breastfeeding may not be the surefire answer that many women consider it to be, according to two Cincinnati researchers.
In their study, all women - whether they breastfed or not - lost body fat after giving birth. However, the moms who did not breastfeed lost weight quicker during the first six months after delivery than did breastfeeding mothers.
“It is important that women are aware that, although there are many advantages to breastfeeding, faster loss of the fat gained during pregnancy is not likely to be one of those advantages,” study author Dr. Karen S. Wosje, of the Cincinnati Children’s Hospital Medical Center told Reuters Health.
Despite anecdotal evidence cited by some women, conflicting reports exist about the link between breastfeeding and postpartum weight loss. In one study, researchers reported greater weight loss among breastfeeding mothers up to 12 months after delivery in comparison to mothers who did not breastfeed. In another, no such association was found.
In the current study, Wosje and co-author Dr. Heidi J. Kalkwarf monitored the body composition of a total of 326 lactating and nonlactating women to determine the effect of breastfeeding on postpartum weight loss. About half that number were also randomly assigned to take a calcium supplement, which some researchers have said may also promote weight and fat loss after delivery.
The team found that the loss of overall body fat, as well as fat in the arms and legs occurred at a faster rate among women who did not breastfeed than among those who did, and calcium supplementation did not affect the reduction in fat mass.
Yet, all of the women, regardless of their breastfeeding status, lost fat in their trunk area - the chest, stomach and pelvic region - during the study period, which lasted from two weeks to six months after delivery, Wosje and Kalkwarf report in the American Journal of Clinical Nutrition.
“Women who did not breastfeed lost fat, not weight, at a faster rate than women who breastfed,” Wosje said. The reason for this is unknown, but Wosje speculates that the “non-breastfeeding women were restricting their calorie intake in the effort to lose weight, whereas breastfeeding women did not restrict calorie intake because they presumed they would lose weight by breastfeeding.”
The extra body fat gained during pregnancy is typically deposited in the thighs and trunk, which, research shows, seems to be the primary energy sources used to support women’s breastfeeding. This might explain the finding that breastfeeding women seemed to use the energy in their trunk and leg fat but gained fat in their arms, whereas the non-breastfeeding women were able to reduce their overall percentage of body fat as well as lose fat in specific areas.
“It is possible that the small increase in arm fat of the breastfeeding women was part of the overall shifting of fat stores that occurs during breastfeeding,” Wosje said. “We do not know if the arm fat gain persists beyond six months post-childbirth.”
Another possible reason breastfeeding mothers did not lose more fat or weight than mothers who did not breastfeed may involve their increased levels of the hormone prolactin. Research shows that this hormone not only stimulates milk production early in lactation but also stimulates the appetite of breastfeeding women.
Breastfeeding is still better for the health of the infant, however, as various studies have shown that breastfed babies are less likely to be underweight or overweight and are less susceptible to disease than formula-fed babies. But based on the current study’s findings, mothers should not choose the breast over the bottle as a means of quickly losing the fat gained during pregnancy.
“Mothers should choose to breastfeed their infants for reasons other than achievement of faster fat loss,” Wosje said.
SOURCE: American Journal of Clinical Nutrition, August 2004.
Revision date: July 4, 2011
Last revised: by Janet A. Staessen, MD, PhD