Weight Fluctuations Among Normal-Weight Individuals Increases CVD Risk

March 05, 2010

March 5, 2010 (San Francisco, California) — Weight cycling, where an individual's body-mass index (BMI) fluctuates during a two-year period, is associated with an increased risk of cardiovascular disease among normal-weight individuals, according to the results of a new study [1]. These weight cyclers have a risk of adverse events similar to individuals who are overweight, while overweight individuals who cycled did not experience an additional increased risk of cardiovascular events over and above the risk associated with their increased weight, report investigators.

"We were looking at the overall weight status--how heavy the individual was between the ages of 40 and 55 years--and whether or not the weight went up and down during that period," lead investigator Dr Molly Waring (University of Massachusetts Medical Center, Worchester) told heartwire . "We found that compared with people who were normal weight, or pretty steady weight, the normal-weight individuals whose weight went up and down during the two-year period, as well as those who were overweight and obese, all had a higher risk of cardiovascular disease and death."

The results of the study were presented here this week at EPI|PNAM 2010, the Cardiovascular Disease Epidemiology and Prevention and Nutrition, Physical Activity, and Metabolism 2010 Conference.

Weight Across Time Rather Than a Point in Time

To heartwire , Waring said the purpose of the study was to examine patients' weight across a spectrum of years rather than a point in time to determine whether changes in weight influenced their health risk. The thinking, she said, was that a patient's weight at age 40 or 50 was less relevant than weight over the course of a lifetime.

Using data from the Framingham Heart Study, the researchers quantified the effect of overall weight status and weight cycling in 1429 participants aged 40 to 55 years old. Weight status and weight cycling was categorized using component scoring that allowed researchers to capture the weight patterns across middle age. In this study, weight cycling was defined as a change of one BMI unit within the two-year period. That works out to be about five pounds for an individual who is five feet tall and seven pounds for six-foot tall male, said Waring.

Results showed that compared with an overall normal-weight trajectory without weight cycling, normal-weight individuals whose weight went up and down over the study period had a 50% greater risk of cardiovascular disease events and a 40% greater risk of cardiovascular mortality. These normal-weight cyclers were also at a significantly increased risk of cerebrovascular accidents and coronary heart disease events when compared with normal-weight individuals whose weight did not fluctuate.

Risks of Cardiovascular Disease and Cardiovascular Mortality

Events Adjusted hazard ratio (95% CI)
Cardiovascular disease events  
Normal weight, no cycling Referent
Normal weight, cycling 1.5 (1.2–2.0)
Overweight, no cycling 1.7 (1.3–2.2)
Overweight, cycling 1.8 (1.4–2.2)
Obese 2.7 (2.0–3.5)
Cardiovascular mortality  
Normal weight, no cycling Referent
Normal weight, cycling 1.4 (1.0–2.0)
Overweight, no cycling 1.3 (0.9–2.0)
Overweight, cycling 1.6 (1.1–2.2)
Obese 1.8 (1.1–2.9)

Comparatively, overweight individuals who maintained a constant weight and those whose weight cycled during middle age had similar risks of cardiovascular, cerebrovascular, and coronary heart disease events. In addition, they had similar risks of cardiovascular and overall mortality.

"Among people who are overweight, those whose weight varied within the two-year period were not at any higher risk of cardiovascular disease and death than those overweight individuals whose weight remained steady," said Waring. "I think that's a positive finding from the study, because we know how difficult it is for patients to lose weight and to keep it off. It's encouraging in that if they are trying to lose weight but gain it back because they're not able to maintain the lifestyle changes, it's not putting them at greater risk. The message is to keep trying."

For normal-weight patients, this study emphasized the importance of keeping the weight off, because even periods of normal weight won't protect against cardiovascular disease events if the patients' weight fluctuates up and down, she said.

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