Yo-yo dieting, a.k.a. “weight cycling,” a continuing pattern of losing and regaining weight, can be one of the most frustrating experiences people with weight problems may experience.

The term, first created by Dr. Kelly D. Brownell of Yale University’s Rudd Center for

Food Policy and Obesity, refers to a decrease of 10 pounds or more of body weight through significant calorie restrictions, followed by sometimes rapid, sometimes gradual weight gain after the regimen ends. It is an unproductive process that can lead to emotional upheaval and serious health problems.

Some diet regimens require participants to adopt radical changes in their existing eating patterns, including cutting out entire food groups such as fat or carbohydrates. While this can result in quick weight loss, it also makes it tempting to revert to old eating habits later on.

When a diet, any diet, includes starvation-like low-calorie intake, the body first adapts to conserve energy by slowing down the metabolism (the way it burns food for energy). But when the near starvation period is then followed by a return to former eating habits (e.g. regular overeating or bouts of binge eating), the body reacts by storing fat faster. That is why many dieters end up heavier than they were before their initial weight loss efforts.

Also, with each new cycle of weight gain and weight loss, the metabolism becomes less efficient, making it even harder to repeat former successes.

“Unfortunately, yo-yo dieting is probably the most common outcome of efforts to lose weight,” said Dr. Thomas Wadden, director of the Center for Weight and Eating Disorders at the University of Pennsylvania School of Medicine in an interview (http://www.usatoday.com/news/health/weightloss/2009-05-26-yo-yo-diet_N.htm) on the subject with USA Today. “People do lose weight, but the majority regain some or all of their weight, whether it’s over one year, two years, three years or five.”

The experience of seeing one’s initial successes being undone time and again takes a toll on people emotionally, which can be quite stressful, Dr. Wadden said. “People often feel ashamed, humiliated and powerless.”

But it’s more than just feelings of shame and humiliation that aggravates the problem, according to Dr. Tracy L. Bale of the University of Pennsylvania who conducted a study (http://www.jneurosci.org/content/30/48/16399.full?sid=8e37e3e6-c80b-4007- bf89-1fdc7d327a1b) on the high failure rate of weight management, published in the Journal of Neuroscience. Dr. Bale and her colleagues found that dieting itself can change how the brain responds. Based on experiments with mice, the researchers observed that alternating eating behavior – like switching from near-starvation to overeating – lead to changes in the brains of the animals. In other words, the experience of famine (dieting) “taught” the rodents to overindulge in highly caloric foods as soon as they had access to them, just in case there would be more lean times in the future. From an evolutionary perspective, this makes a lot of sense and there is no reason to think that these mechanisms won’t apply to humans as well. The problem is that in our food environment today with its plentiful supplies these effects often work against us.

However, not everyone agrees that yo-yo dieting is an all-around bad thing. At least one study (http://www.ohio.edu/research/communications/yoyodiet.cfm) suggests that losing weight, even if it’s gained right back, is better than remaining obese all the time. Based on experiments with mice, researchers found that yo-yo dieters may be healthier and live longer than those who do nothing about their weight. Dr. Edward List, a scientist at Ohio University’s Edison Biotechnology Institute and lead author of the study report thinks that gaining and losing weight by itself does not seem detrimental to one’s life expectancy.

Still, some damage that is hard to reverse can result from significant weight fluctuations, one being muscle loss during rapid weight reduction, which is often replaced by fat gain afterwards. Both affect the metabolic rate, and not in a good way.

So what are workable alternatives to yo-yo dieting? Obviously, there are no easy answers. Setting realistic weight loss goals is certainly a part of it. Opting for small changes over time instead of trying for dramatic results is also recommended. So is observing appropriate portion sizes. And the need for regular exercise goes without saying.

Deprivation alone will rarely do the trick. If you don’t enjoy the kind of food your weight loss diet requires, you will not stick to it no matter how beneficial it may be to your health. So, eat the food you like, get as many important nutrients as possible and give your body the time it needs to readjust. After all, you want to lose weight not only for the pounds but for your health’s sake.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog, “Food and Health with Timi Gustafson R.D.” (http://www.timigustafson.com), and at amazon.com. You can follow Timi on Twitter (http://twitter.com/TimiGustafsonRD) and on Facebook (http://www.facebook.com/TimiGustafsonRD).