The yo-yo is a toy that dates back to Ancient Greece and may have originated even earlier in China. There is, however, nothing playful about our experiencing unintentional weight fluctuations that go up and down like a child's yo-yo. According to the Oxford English Dictionary, the first reference to "yo-yo dieting" appeared in an advertisement in the New York Times in the early 1960s. In the scientific literature, the term began appearing in the 1970s and 80s, where it is also referred to more technically as "weight cycling." Since about 75 to 95% of those who lose weight will tend to regain some, all, or even more than their initial weight before their weight loss, weight cycling is a common enough occurrence. In fact, some researchers like Foster and his colleagues believe "Weight regain remains the most common long-term outcome of obesity treatment."

Weight cycling can be an intentional pattern, such as seen with professional ballet dancers, wrestlers, or boxers (e.g. remember Robert DeNiro's considerable weight gain when he played the boxer, Jake La Motta, in Scorsese's Raging Bull.) It can also be a normal pattern, such as seen in the weight gain during pregnancy and subsequent weight loss after a baby's birth. Mostly, though, it is a pattern all too familiar to dieters: cycles of intentional weight loss and subsequent unintentional weight regain over time. For years, researchers have grappled with both the medical and psychological consequences of this pattern. Results, though, have been inconsistent, partly because there is no definition of what constitutes weight cycling: For example, there is no standard regarding how much weight loss is involved, over what period of time, or even how often or how many weight cycles do occur. Some studies don't even specify whether the weight loss is intentional (e.g. through dieting or exercise) or unintentional (e.g. through disease, medication, mood disorders). Furthermore, investigators may rely on self-reports of their patients, often years after the fact such that data are subject to the inevitable and natural distortions of memory. Typically, as well, we know that both men and women tend to overestimate their height and underestimate their weight when they self-report.

Those who have lost weight appreciate that it is often much easier to lose than to maintain that loss over time. After all, weight maintenance is much less reinforcing than weight loss. And often dieters are not realistic in terms of the amount of weight they can actually lose. Weight maintenance may involve accepting a shape and weight previously regarded as unacceptable or just "not good enough." When dieters fail at weight maintenance, many inevitably try again, often subjecting themselves and their bodies to countless weight fluctuations over time. Incidentally, a recent study by Erez and colleagues from Israel suggests that it may be possible to predict from both genetic studies and from levels of the hormone leptin which people are most susceptible to weight regain.

What about the clinical significance of this yo-yo pattern? After all, if there are negative medical or psychological consequences to weight cycling, should health professionals always be recommending weight loss again to those who have regained their previously lost weight?   For example, there have been suggestions in the scientific literature, particularly in some (but not all) animal studies, that metabolism may be negatively affected such that less weight is lost after a subsequent regain. There has also been the suggestion that bone density may be affected by repeated cycles. Probably, though, it is more likely that those on diets may fail to get adequate amounts of supplemental calcium and vitamin D. 

What about the psychological consequences of weight cycling? Clearly, for some predisposed to anxiety and depression, weight regain may lead to decreased self-esteem and self-confidence and particular feelings of loss of control. There is even the suggestion that weight cycling is associated with binge-eating.

Though weight cycling may not be a completely benign phenomenon, some researchers, such as Prentise and colleagues, have suggested that weight cycling may have been common in primitive times when our ancestors had to deal with intermittent cycles of famine and plenty.

The jury is still out on all the possible effects of weight cycling. A report some years ago from the National Task Force on the Prevention and Treatment of Obesity concluded that the "available evidence" of any adverse effects of weight cycling did not override all the potential benefits of weight loss.  And even a weight loss of ten pounds can have substantial positive effects on cardiac health, diabetes, blood pressure, sleep, and sex.  Drs. Mehmet Oz and Michael Roizen have had an effective campaign this past year of "Just ten"-indicating that even a weight loss of just ten pounds in those overweight or obese is worthwhile, a conclusion supported by weight expert, Dr. Louis Aronne, of Weill Cornell Medical College.

Bottom line: still 'tis better to have lost and regained than never to have lost at all!

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