Yo-Yo Dieters Show Lower Levels of "Good" Cholesterol, Could Pose Heart Disease Risk, Say Researchers from National W.I.S.E. Study
PITTSBURGH, October 31, 2000 — Women who repeatedly gain and lose weight, especially if they are obese, have significantly lower levels of HDL or "good" cholesterol than do women who maintain their weight, putting the weight cyclers at increased risk of cardiovascular disease.
These findings were published in the November issue of the Journal of the American College of Cardiology by researchers from four institutions conducting the Women’s Ischemia Syndrome Evaluation (W.I.S.E.) study, sponsored by the National Heart, Lung and Blood Institute.
"These findings may have a great significance because 40 percent of adult women report attempts to lose weight, and many will gain it back," said Marian Olson, M.S., research associate at the University of Pittsburgh Graduate School of Public Health and first author of the paper. "While obese weight cyclers tended to have the lowest HDL cholesterol levels among all weight cyclers in the study, even thinner women who repeatedly gain and lose weight showed lower HDL levels than those who maintain their weight." Low HDL cholesterol is a major risk factor for heart disease.
In this cross-sectional study, weight cycling was defined as intentionally losing at least 10 pounds at least three times during one’s life. The study involved 485 women who were undergoing coronary angiography to evaluate chest pains.
Of the 130 participants who reported a history of weight cycling, 19 percent cycled 10-19 pounds, six percent cycled 20-49 pounds and two percent cycled 50 pounds or more. Women of greater body mass index (BMI) tended to cycle more weight and to exhibit the lowest HDL levels. However, the effects of weight cycling on HDL levels were independent of other factors known to affect HDL levels, such as BMI, excess abdominal fat, smoking, lack of exercise, alcohol intake, hormone replacement therapy, diabetes and race.
Weight cyclers had an average of seven percent lower HDL levels (52 mg/dl) than did non-cyclers (56 mg/dl). This 4-mg difference is important because previous studies have shown that for each 1 mg/dl increase in HDL cholesterol, women may reap a three percent decrease in coronary heart disease risk. Also significant is that total cholesterol levels were eight percent higher in weight cyclers.
"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," said C. Noel Bairey-Merz, M.D., medical director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Research Institute, and senior author of the paper.
Compared with women who maintained their weight, cyclers had higher BMI, exercised more and had a greater physical capacity for performing everyday activities. The two groups did not differ in cardiac risk factors such as blood pressure, blood sugar or waist-to-hip ratio, or in menopausal status, use of hormone replacement therapy, or prevalence of diabetes or coronary artery disease. Weight cyclers also tended to be white, as well as younger and better educated than the non-cyclers.
While low HDL levels constitute a significant risk factor for coronary artery disease (CAD), the investigators did not note a direct association between weight cycling and CAD.
"It is possible that there could be a lag time between the drop in HDL levels and its effect on the development of heart disease," explained Steven Reis, M.D., assistant professor of medicine at the University of Pittsburgh, director of the women’s Heart Center at the University of Pittsburgh Medical Center (UPMC) Cardiovascular Institute, a W.I.S.E. principal investigator and co-author of the paper. "Additional research is necessary so that these women can be followed over a period of time."