Yo-Yo Dieting Raises Risk of Heart Attack and Stroke

By Jane Farrell

Fluctuations in weight, blood pressure, cholesterol and/or blood sugar levels in otherwise healthy people may be associated with a higher risk of heart attack, stroke and death from any cause compared to people with more stable readings, according to new research in the American Heart Association’s journal Circulation.

This is the first study to suggest that high variability of these risk factors has a negative impact on relatively healthy people. The study is also the first to indicate that having multiple measures with high variability adds to the risk.

Compared to people who had stable measurements during an average 5.5 year follow-up period, those with the highest amount of variability (in the upper 25 percent) on all measurements were:

127 percent more likely to die;

43 percent more likely to have a heart attack;

41 percent more likely to have a stroke.

Using data from the Korean National Health Insurance system, researchers examined data on 6,748,773 people who had no previous heart attacks and were free of diabetes, high blood pressure, or high cholesterol at the beginning of the study. All participants had at least three health examinations between 2005 and 2012 (every two years is recommended in the system). Records of the exams documented body weight, fasting blood sugar, systolic (top number) blood pressure and total cholesterol.

Because high variability could result from either positive or negative changes, the researchers looked separately at the effect of variability in participants who were more than 5 percent improved or worsened on each measurement. In both the improved and the worsened groups, high variability was associated with a significantly higher risk of death.

“Healthcare providers should pay attention to the variability in measurements of a patient’s blood pressure, cholesterol and glucose levels as well as body weight. Trying to stabilize these measurements may be an important step in helping them improve their health,” said Seung-Hwan Lee, M.D., Ph.D., senior author of the study and professor of endocrinology at the College of Medicine of the Catholic University of Korea in Seoul, South Korea.

The study was observational, which means that it cannot prove a cause-and-effect relationship between high variability and the risk of heart attacks, strokes or death from any cause. The study also did not delve into the reasons behind the fluctuations in the participants’ risk factor measurements.

“It is not certain whether these results from Korea would apply to the United States. However, several previous studies on variability were performed in other populations, suggesting that it is likely to be a common phenomenon,” Lee said.

Statements and conclusions of study authors published in American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect the association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. The Association receives funding primarily from individuals. Foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The Association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations and health insurance providers are available here.

About the American Heart Association

The American Heart Association is devoted to saving people from heart disease and stroke – the two leading causes of death in the world. We team with millions of volunteers to fund innovative research, fight for stronger public health policies and provide lifesaving tools and information to prevent and treat these diseases. The Dallas-based association is the nation’s oldest and largest voluntary organization dedicated to fighting heart disease and stroke. To learn more or to get involved, call 1-800-AHA-USA1, visit www.heart.org or call any of our offices around the country.