Science of yo-yo dieting

Conway McLean, DPM

I am happy to report that we now know more about nutrition than we ever have. Clearly, we are making progress. We have advanced to the level of “horrendous” after moving up last month from “abysmal.” There are many reasons for this, one being humans make poor subjects when it comes to participating in multi-year nutritional studies. In addition, the genetic make-up of each individual introduces a massive group of variables that are nearly impossible to account for.

Often, when the subject of nutrition comes up, the conversation leads to body weight. Unfortunately, this discussion is multi-faceted, and encompasses cultural norms, myths, and a host of unscientific beliefs and mores. In recent years, lay and popular literature has claimed that weight cycling may be more detrimental than simply remaining overweight. What does the scientific literature tell us about dieting, obesity, health, and the associated risk of developing chronic diseases? If we had better research on nutrition, it probably could, but we don’t!

The psychological ramifications of society related to body image are far beyond the scope of this brief article. One need only open the pages of any popular magazine to see the incredible amount of attention paid to dieting. The obvious conclusion is that being overweight is viewed with tremendous disdain in our culture. Forty-five million Americans will go on a diet this year, and many will lose weight. Yet the chances of keeping that off for more than a year or two are poor, about 3 per cent. Still, people are looking for an answer, and naturally, something quick and easy is preferable. Hence, the weight loss industry is estimated at approximately 61 billion dollars.

But is being fat really bad for you? We hear it often enough, and from every possible source of medical information. Apparently, how obesity affects your health depends on many things, including your age, gender, where you carry your body fat, and how physically active you are. Some studies have indicated a high body mass index (the oft quoted BMI), which is one of the most popular measures of obesity, is not necessarily unhealthy. Perhaps it is not necessarily better for your health to be thin, especially taking into consideration what some people have to do to get there.

The national obsession with weight got a boost back in the 40’s when a particular insurance company collected numerous data points to create “desirable” height and weight charts. For the first time, people and their doctors could compare themselves to a standardized notion of what they “should” weigh. The BMI distills numerous components of health into one number, based solely on height and weight. Although commonly used, one’s BMI does not take into account where you carry extra weight.

It turns out, this is of tremendous importance. If fat builds up mostly around your stomach (sometimes called apple-shaped), you are at greater risk for type 2 diabetes, high blood pressure, high cholesterol, and coronary artery disease, as compared to people who carry extra fat around the hips (sometimes called pear-shaped). Therefore, your waist size is a strong predictor of your risk of health problems. If you are obese and have unhealthy eating or activity habits, you have a higher risk for the previously mentioned conditions, as well as gallstones, a stroke, sleep apnea, among other diseases.

One of the consequences of an emphasis on weight in our culture is the phenomenon known as weight cycling. The popular aphorism for this situation is yo-yo dieting, a termed coined by a researcher at Yale. This refers to the cyclical loss and gain of weight, resembling the up-down motion of a yo-yo. All the studies performed consistently reveal the over-all success rate of diets, in general, is extremely poor. Thus, when someone tries one “diet” and is not successful over time, they will often assume it was not the right plan for them. Then it’s off to another!

One new study found repeated dieting can ultimately lead to weight gain since your brain interprets these oscillations in eating patterns as brief, repeated periods of famine. Your body goes into survival mode and prompts the storage of fat for future shortages. This is an evolutionary measure; animals respond to shortages in food supply by gaining weight to stay alive. But the reasons that so many people are dieting is more than just cultural: for years, medicine has been telling us that being overweight is unhealthy, and ultimately dangerous. But is this what the research tells us? Actually, it seems it depends on how you define’obesity and, as mentioned, where you carry those extra pounds.

Women are more likely to change their weight frequently versus men. This is because they are more likely to attempt various diet programs, ie they are practicing yo-yo dieting. This is physically dangerous according to many studies. One reason weight cycling may be harmful is the “overshoot theory.” When someone changes weight frequently, gaining weight increases health risk by raising blood pressure, cholesterol and body fat. When one loses the weight, these levels drop, but not all the way to their healthy baseline. If these cycles keep repeating, a person’s health will decline, even if they appear “normal.”

Yo-yo dieting can result in fluid shifts and electrolyte changes, including potassium, that can cause deadly heart arrhythmias, especially in susceptible middle-aged women. Men are also negatively affected by weight cycling. Popular diets want you to lose weight quickly, often by reducing your caloric intake excessively, some by as much as a 1,000 calories a day. When this happens, the dieter’s levels of electrolytes are depleted, a potentially hazardous situation.

When you’re constantly taking your body in different directions-from heavier to thinner-and switching gears in how you get there, it also takes an emotional toll on your mental well-being. Yo-yo dieting is not only physically damaging, but psychologically as well. But you can still lose weight, even if you’ve been a yo-yo dieter. One recommendation concerns the mind-body connection. Start by connecting with your body. Cultivate an appreciation for yourself just as you are.

Remember: moderation is the key. Do not think you are going to lose your extra pounds in a month, when it took you years to gain them. The most successful weight loss programs practice moderation. Attempt a gradual reduction in calories, accompanied by adding exercise, ideally at least 45 minutes several times a week. When someone can make these changes long term, they will feel better, and be healthier. So, the take-home message today: don’t diet! It’s so much easier than that: just eat healthy, and, of course, get exercise.

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at