Many women will lose and regain the same 10 or more pounds several times over the course of their lifetime. It seems innocent enough, if not typical. In fact, up to 40% of adult women say they have tried to lose weight, but now new research suggests those repeated gains and losses might actually be harmful.

In a study of women undergoing tests for chest pain, those who reported losing 10 or more pounds at least three different times, known as yo-yo dieting, had lower levels of "good" HDL cholesterol than women who maintained a stable weight. Low HDL cholesterol is a major risk factor for heart disease. The study appears in the November issue of the Journal of the American College of Cardiology.

Of 130 women in the study who reported yo-yo dieting, 19% gained and lost 10 to 19 pounds, 6% gained and lost 20 to 49 pounds, and 2% gained and lost 50 or more pounds. The heaviest women who reported gaining and losing the greatest amounts of weight also had the lowest levels of HDL cholesterol.

Yo-yo dieters had an average of 7% lower HDL levels compared with women who did not yo-yo diet. Although the dips in cholesterol were not directly associated with heart disease, the researchers say over time, reductions in HDL cholesterol could increase one's risk.

But lead author Marion Olson, MS, says people should be careful about interpreting the findings since all the women in the study were being evaluated for chest pain. Olson, a research associate the University of Pittsburgh Graduate School of Public Health, says, "there should be further investigation in this area to see if it does apply to all women."

Alice H. Lichtenstein, DSc, says studies like this one are difficult to draw firm conclusions from because they rely on the women recalling their various attempts at weight loss.

"If you asked me over my lifetime how many times I've changed my weight by 10 pounds, I don't think I could tell you,"

says Lichtenstein, who is associate professor of nutrition at Tufts University's Jean Mayer Human Nutrition Center on Aging in Boston. She says the potential for error in remembering those details as well as the special health concerns of the group of women being studied limit the ability to apply the findings to all women. However, she says women who need to lose weight for health reasons shouldn't avoid doing so because of this study.

C. Noel Bairey-Merz, MD, another co-author of the paper, believes that too much emphasis on "dieting" may be keeping the yo-yo dieting syndrome alive.

"[Physicians] don't have a good diet to recommend to anyone. There is no effective long-term weight-loss diet," says Bairey-Merz, medical director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Research Institute in Los Angeles.

Bairey-Merz says in some cases, doctors telling patients to diet is "worse than saying nothing." She points to diet crazes like Phen-Fen and herbal weight loss aids that have been shown to have serious side effects.

"I really think we should probably stop talking about 'diet.' We are not talking enough about exercise, which is very effective for sustained weight loss,"
suggests Bairey-Merz.