A new study just presented at the meeting of the American Heart Association investigated the possible effect of weight cycling (repeatedly gaining and losing weight) on heart disease and death from heart disease in older women.
Lead investigator Dr. Somwail Rasla from Memorial Hospital in Rhode Island analyzed the weight history reported by nearly 160,000 postmenopausal women; follow up was about 11 years. Participants were categorized as underweight, normal-weight, overweight or obese at the start of the study. Then they were further listed as weight cyclers — those who repeatedly lost and regained weight, weight stable, steady weight gainers, and maintained weight loss.
There was an association between weight cycling — also known as "yo-yo dieting" — and the risk of sudden cardiac death. The increased risk was more than three-fold greater in these cyclers than in weight stable women. Weight cycling by overweight or obese women carried no excess risk of death, however. Similarly, women who reported a maintained weight loss or gain had no increased risk of death.
The moral of the story? For older women, if you're normal weight, be happy and leave well enough alone — that is if you accept the results of this study. And there are weaknesses that we should be aware of.
First, the weight data were self-reported, and thus depended on the accuracy and truthfulness of participants' reports. Second, this type of observational study can only provide associations, not causal links. Thus, an increased risk for only normal-weight women may underplay risks of yo-yo dieting for the overweight and obese. But further research will be required to tease out the importance of these associations.