Yo Yo Dieting

By Michael Anchors, MD, PhD​

Last week an article in the New England Journal of Medicine furnished evidence that yo yo dieting increases the chance of a heart attack or stroke. You should not believe this right away because the data were epidemiological, i.e. there was an association between yo yo dieting and heart attack, but association does not prove causation. It might have been for instance that yo yo dieters ate more sugar than no yos or did less exercise. The “dieters” may not have even been dieters at all; the study wasn’t even about yo yo dieting; the data were extracted from a study of Lipitor’s effect on heart disease. The authors merely remarked that people in the study whose weight varied a lot were more prone to heart attack. But weight can vary for many reasons other than dieting.
 
Nevertheless, it is beyond doubt that each time you lose weight and regain, it is more difficult to lose weight the next time. Yo yoing leads to insulin resistance. 
 
Sometimes patients, returning many times, complain that the phen-pro medicines aren’t working like they used to. Usually the problem is not the medicines; it’s yo yoing.