Dieting and aerobic exercise can safely be combined to help breast-feeding moms lose excess weight gained during pregnancy, report UC Davis nutritionists. While dieting-plus-exercise or dieting alone can achieve just about the same amount of weight-loss, the researchers recommend the combination approach because it reduces fat, rather than lean body tissue. "There is strong evidence linking excess maternal weight retention after childbirth to adult obesity," says Kathryn Dewey, a professor of nutrition and a lead researcher on the UC Davis study. "Consequently, women need guidelines for how they can safely lose weight while still breast-feeding " In 1994, Dewey reported research findings indicating that moderate aerobic exercise was compatible with breast-feeding. The current study is the first to scrutinize the effects of both dieting and exercise while a woman is breast-feeding. During the 11-day study, graduate student Megan McCrory, Dewey and colleagues monitored 67 participants who were either dieting, dieting and exercising or making no change in their diet and activity. Women in the two test groups trimmed their available calories by 35 percent. The dieters did so only by reducing the amount of food they ate, while participants in the other group restricted their food to a lesser extent but also walked, jogged, did aerobics, bicycled, swam or used exercise machines. At the end of the study, women in both of the test groups had lost an average of 2.8 kg (nearly 4 pounds). Those in the control group had lost .16 kilograms (about one-third of a pound), which is normal for breast-feeding women. The quality and quantity of the participants' breast milk was not affected, nor did the nursing infants' growth and weight-gain suffer. However, the researchers caution that this was a short-term study and do not recommend such a rapid rate of weight loss over longer periods. Findings from the study are reported in the May issue of the American Journal of Clinical Nutrition.