Why Dieting Backfires The Best of Intentions
Rebound weight gain in dieters is so common that it has become an adage. We witness the weight-loss rebound all around us—in movie stars, diet spokespersons, our neighbors, ourselves. And, we speculate: Is loss of willpower to blame? Is it just falling back into old eating patterns? Is it apathy —do dieters just not care enough to keep it off?
Well, it’s more complicated than that, as you know by now. Diet rebound is not just a function of overeating, emotions or lost willpower, even though we have thought this way for decades. Remember, the underlying truth is in the principles of adaptation and survival. The rebound phenomenon is about bodies surviving diet famines by prompting necessary feasts. The principles of adaptation and survival offer compelling explanations for these maddening realities. And, these explanations challenge, and even contradict, the typical diet regimen in this country. At the same time, they provoke other questions that must be answered: Exactly how do bodies fight against dieters’ eat-less efforts, and how do dieters gain back the weight they lose?
Exactly How Bodies Sabotage Dieters
There are five specific ways that bodies react to dieting, fighting dieters’ efforts to lose weight and, ultimately, causing dieters to fail. These five adaptations to dieting (famine) can be divided into two categories: energy conservation and preventing weight loss.
Bodies protect fuel reserves by
1. Lowering the metabolic rate
2. Lowering energy and activity levels
Let’s look at the first way bodies fight dieters:
Bodies protect fuel reserves by lowering the metabolic rate.
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Many dieters complain that this “problem” applies to them. It does! Dieters really do experience lowered metabolic rate when they restrict their eating. This decrease in metabolism is simply an adaptation to the decreased food intake. In order to continue functioning on a limited fuel supply, a body must lower its basic fuel needs. So, a body in famine adjusts to getting along on the restricted fuel intake. Oxygen consumption goes down and the core body temperature drops. These are a few of
the obvious changes the body goes through. The problem with this energy conserving change is that these fuel efficiency tactics may continue beyond the end of the diet, even afer food is plentiful.
Marian Apfelbaum, M.D. was involved in hundreds of research studies on obesity and weight loss. His research showed that the metabolic rate of people who are dieting drops by 15 percent to 30 percent. This is why dieters ofen complain of feeling tired, apathetic and unmotivated.
George Bray M.D. discovered a 20 percent decrease in metabolic rate in as little as two weeks of dieting—a decrease measurable within 48 hours of caloric restriction. This big decrease in baseline energy expenditure suggests the bodies become even more metabolically efficient, lowering energy use because food restriction from any source, external or internal, signals danger to the body, he said.
A number of obesity researchers (Boyle, Storlien and Keesey, and others) showed that repeated calorie restriction in animals might have permanent effects on metabolism The researchers interpreted the findings to mean that that these metabolic depressions were adaptations to food restriction. So, simply put, bodies react fast to under eating by lowering energy expenditure, and over time repeated food restriction may cause a lasting depression of metabolic rate. This implies that there is a possibility that, with long-term dieting, individuals may actually make it more and more difficult to lose weight at all. I have heard such testimonies.
The Best of Intentions
When metabolism is depressed, dieters’ bodies reflect this:
Bodies protect fuel reserves by lowering energy and activity levels.
Underfed bodies are likely to be more tired and less inclined to move around unnecessarily. This is easy to understand if you think about a real famine. Let’s say you get lost in a forest without any food for several days. During that time, your body adjusts to the lack of food by conserving surface heat. You get cold, literally. And you want to sit down. You may even get sleepy.
Among dieters, those who drop out of an exercise program are the rule rather than the exception. In a 1980 study, researchers Kelly Brownell, PhD, and Albert Stunkard, M.D., found that 50 percent of overweight people who were prescribed a weight-loss exercise program drop out, even when they had “compelling medical reasons” to adhere to it. Many other researchers confirmed this finding.