By CATHERINE SAINT LOUIS


When Jessica Jochim returned to work after her three-month maternity leave, she was the envy of her co-workers at Babies “R” Us. Mrs. Jochim, who had gained 18 kilograms carrying her first child, steadily slimmed until she was a size 4 again. Yet, exercise was a pre-baby relic. She wasn’t dieting, either. In fact, every two hours, she snacked as if on cue.

What was her secret? Breastfeeding her newborn James on demand, and using a breast pump to take milk home to him.

“All the ladies at work started joking they were going to go in back and pump so they could start losing weight like I was,” said Mrs. Jochim, a mother of three from Vancouver, Washington. “I had a baby suckling 600 calories a day out of me.”

That breast-feeding gives mothers an edge shedding baby weight has long been suspected. But lately, a parade of celebrities has attributed their postpartum slimming to nursing, bringing this age-old topic back into the spotlight. Adding to the conversation is a large study that suggests that weight loss through breast-feeding is not a myth.

Earlier this year, the actress Rebecca Romijn called breast-feeding her new twins “the very best diet I’ve been on.” After Angelina Jolie posed for the November 2008 cover of W magazine nursing one of her twins, she said that it had helped her regain her figure. (That cover inspired a bronze statue of a nude Ms. Jolie double-nursing her newborns that was exhibited in London last month.)

“Nobody wants to admit they are doing it for themselves, or ‘I’m doing it to help myself look hot again,’” said Jesse Comer, from Portland, Oregon, whose main motivation to breast-feed was her baby’s health. “It’s tough to admit to other people that everything isn’t about the baby.” But Ms. Comer “felt like until the weight was off, I wouldn’t feel myself.”

Last year, an epidemiological study of 36,000 Danish women found that the more a mother breast-feeds, the less weight she retains six months after birth. A few factors determined how much she lost: whether a woman was overweight before pregnancy, what she gained while expecting and duration of nursing, said Kathleen M. Rasmussen, an author of the study and a nutrition professor at Cornell University in Ithaca, New York.

The study’s convincing data impressed experts like Cheryl A. Lovelady, a nutrition professor at the University of North Carolina at Greensboro. But, she said, referring to the Danish women, “we don’t breast-feed as long as they do.” Other studies have found that breast-feeders don’t necessarily shed fat quicker than women who feed their newborns formula. A small double-blind randomized study conducted at Cincinnati

Children’s Hospital Medical Center found that non-lactating women lost more body fat than lactating women at six months, and at a faster rate. Karen Wosje, its lead author, suggested that the appetite stimulant prolactin could lead nursing mothers to overeat. Or the fact that non-lactating mothers were able to exercise more vigorously than the nursing mothers in the first half year may have tipped the scale in their favor.

What then to make of tales of prodigious eating among thinning breast-feeders? Dr. Lovelady suspects some of them who say they eat without consequence used to be “restrained eaters.” That is, they ate fewer calories than they expended - say, 1,700 calories instead of 2,000 - which, counterintuitively, slowed their metabolism. Once pregnant, they ate enough to keep their metabolism humming for the sake of their baby. Postpartum, they are losing about half a kilogram a week, Dr. Lovelady. Yet, “they are eating a whole lot more” since making milk requires about 500 calories daily.

Others suggest that women who view breast-feeding as a dieting tool may have “deeper body issues,” said Claire Mysko, an author of “Does This Pregnancy Make Me Look Fat?”

Melissa Ramsay Miller, a nursing mother of 4-month-old Luella in South Hadley, Massachusetts, is clear-eyed about the limits of breast-feeding’s ability to “get her body back.” She has two kilograms left to lose, but said she has a “soft stomach.” “It doesn’t make sense it would go back to what it was before,” she said matter-of-factly. “I’m O.K. with that.”


JODI HILTON FOR THE NEW YORK TIMES / Melissa Ramsay Miller doesn’t expect nursing to help her regain her toned figure.