The Yo-Yo Dieting Linked to Bad Cholesterol

      Women who "yo-yo" diet have significantly lower levels of "good" cholesterol than women who maintain a steady weight, putting the dieters at increased risk of death from heart disease, researchers report in a new study.

      "These findings may have great significance, because 40 percent of adult women report attempts to lose weight, and many will gain it back," said Marian Olson, a research associate at the University of Pittsburgh Graduate School of Public Health and first author of the study, published Wednesday in the Journal of the American College of Cardiology.

      Although doctors have noted for years that up-and-down dieting is associated with an increased risk of death from heart disease, the new research is the first to suggest the mechanism behind the link.

      The cholesterol subcomponent called high-density lipoprotein "is particularly important for women, because it appears to be a better predictor of cardiovascular disease in women compared to men,'' said Dr. C. Noel Bairey Merz. She is the medical director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Medical Center in Los Angeles and senior author of the study.

      For the study, weight cycling was defined as intentionally losing at least 10 pounds at least three times during a person''s lifetime. Twenty-seven percent of the 485 women in the study fit the criteria. All the women in the study were undergoing coronary angiographs to evaluate chest pains at one of four medical centers.

      Overall, the women who reported weight cycling had HDL levels 7 percent lower than those who reported no weight cycling. And the good cholesterol levels decreased more among women who had lost the most weight.

      On average, there was about a 4 milligram per deciliter of blood difference in good cholesterol between the weight cyclers and the noncyclers. That''s a big difference, since earlier studies have shown that for each milligram''s increase of HDL, coronary heart disease risk drops 3 percent.

      "While obese weight cyclers tended to have the lowest HDL levels among all weight cyclers, even thinner women who repeatedly gain and lose weight showed lower HDL levels than those who maintained their weight,'' Olson said.

      The effects of weight cycling held true independent of other factors that are known to affect HDL levels, like body mass index, excess abdominal fat, smoking, lack of exercise, alcohol intake, hormone replacement therapy, diabetes and race.

      But Dr. Mary Malloy, of the Cardiovascular Research Institute at the University of California-San Francisco, observed that while weight cycling does seem to predict lower HDL, it''s still "not nearly as strong a predictor as other factors such as smoking, diabetes and high levels of triglycerides.

      "More severely obese women may weight cycle more in their attempts to lose weight. And often their chosen diet is low in fat, and these diets are associated with lower HDL levels,'' Malloy added.

      "The bottom line is, while severely overweight women should try to reduce their weight to avoid the many health problems caused by obesity, women who are not obese should try to maintain a stable weight and weight cycling should be discouraged for everyone."

Copyright 2000 Scripps Howard News Service