Effects of Yo-Yo Dieting

If you’ve heard them once, you’ve heard them a millions times: “Dieting decreases your metabolism” and “I can’t lose weight because I have been dieting my whole life and I gain back more than I lose.” I have even heard these excuses used by clients when they are deciding whether it’s the right time to make lifestyle changes. “Why even bother?” they ask. “My metabolism is so slow from years of being on and off diets.” If these phrases are all too familiar to you, then you are going to be thrilled by what you learn in this month’s article.

Yo-yo dieting is technically called “weight cycling” by researchers, and, although a specific number of pounds or dieting attempts isn’t universally accepted, it is generally agreed that the term refers to the repeated loss and regain of body weight. Two-thirds of Americans are overweight or obese; it’s probably not surprising that there are approximately 108 million Americans on a diet in the United States at any given time. Most dieters will make four to five weight loss attempts per year. My guess is that at least three of those attempts coincide with January resolutions, bathing suit season, and the holidays.

The origins of the yo-yo dieting/decreased metabolism theory might stem from a few small studies that reported mixed results with regard to the effects of weight cycling on physiological and psychological outcomes. With that in mind, the researchers at the Fred Hutchinson Cancer Research Center in Seattle wanted to study whether the yo-yo dieting theory was correct. The authors of the Nutrition and Exercise in Women (NEW) study stated that it “remained unclear whether repetitive cycles of weight loss and regain have any significant effect on subsequent success in achieving weight loss, or on the metabolic changes that typically accompany it.” The 12-month long NEW study was conducted on postmenopausal woman who were overweight or obese and had a lifetime history of weight cycling. The women were placed into either a diet and exercise intervention group or the control group. It is important to note that this study looked only at the physiological impact of yo-yo dieting. In what is fabulous news for many, the NEW study results indicated that a “history of weight cycling does not impede successful participation in lifestyle interventions or alter the benefits of diet and/or exercise on anthropometric and metabolic outcomes in women.”

Does this finding surprise you? If you have been on and off the diet train for years and are concerned that you have “ruined” your metabolism, then you have some assurance that you have not. The results of this study don’t suggest that you should continue to yo-yo diet; rather, the recommendation is that you not let concern over a decreased metabolism stand in the way of making lifestyle changes. Metabolism is affected by many factors including, but not limited to, body composition, gender, physical activity, and age. After the age of 20, your metabolism slows down about 2 percent every ten years, and, as we age, we tend to become less active, all of which can lead to extra pounds.

The scientific community may be able to establish that there is minimal physical impact from yo-yo dieting, but what happens psychologically? As dieters lose weight, there is a sense of accomplishment, control, and hopefulness but, as we know, most diets eventually fail; thus, those same feelings of joy can turn instead to feelings of deprivation, frustration, low self-esteem, and mislabeling of hunger and fullness cues. These negative feelings can be huge barriers to making some permanent lifestyle changes. Breaking down these barriers by focusing on small behavior changes that can lead to slow and gradual weight loss is a good place to start. Confidence builds with small successes, such as not overeating at dinner by paying attention to fullness levels, adding in a day of strength training, switching from a grande frappacino to a small, and so on.

With small steps, weight loss goals can be reached and become a permanent way of life, and you will avoid all the drama of getting on and off a diet again. Sure—making significant lifestyle changes is slower and not as dramatic as dieting, but I promise the sense of victory at the end is even sweeter. afm