The Best Diet Is No Diet, Some Researchers Believe

December 10, 1992|by JANE E. BRODY, The New York Times

Throughout history and in much of the world today, human survival has been a battle to get enough to eat.

But not in the United States, where more than a third of the population struggles daily NOT to eat from the cornucopia of high- calorie foods that has become the hallmark of American affluence.

Their goal is to lose and keep off the fatty flesh that once served as insurance against famine and replace it with a sinewy slimness that has become the national symbol of pulchritude for men as well as women.

But as even the most optimistic statistics from commercial programs show, it is a goal that at best only a relative handful of the nation's 60 million to 80 million dieters will ever achieve and that many diet researchers now say should be abandoned until further notice.

Instead of trying to design diets to help their clients achieve a culturally dictated ideal weight, growing numbers of weight-control specialists are focusing on why more than 90 percent of dieters are destined to regain all they lose and then some.

Their findings, in turn, point to a new individualized approach to weight control that they say is more realistic and wholesome and less likely to result in physically and mentally damaging cycles of weight loss and gain.

"What I have to say -- that there is no magical solution to losing weight -- the public doesn't want to hear," said Dr. Janet Polivy, a psychologist at the University of Toronto. "Diets teach people to ignore the natural biological signals of hunger and satiety. Then when they go off the diet they don't know when to stop eating."

Recent studies have highlighted many of the genetic, biological and biochemical factors that seem destined to undermine the resolve of all but the most determined dieters.

Some battle futilely against genes that have programmed their bodies to be efficient storage depots for even the slightest caloric excess. At least half the problems with obesity seem genetically determined, studies of twins and adopted children have shown.

The body cannot distinguish between intended calorie restriction to lose weight and enforced starvation that could threaten survival. Faced with a low-calorie diet, the body goes into a starvation mode: Fewer calories are used to maintain the body at rest and fewer calories are squandered on the production of body heat after eating. And when the diet ends or whenever an excess of calories are consumed, more of the calories are stored as fat.

In fact, many researchers have concluded that the body is programmed to defend a particular weight range or a certain amount of stored body fat that they call the "set point."

After weight loss, there is an increased production of the enzyme lipoprotein lipase that breaks down dietary fats and readies them for storage as body fat.

In addition to the diet-induced reduction in calories used at rest, after weight loss people are smaller and their daily caloric needs are understandably lower -- on average about 12 calories less for every 2.2 pounds lost. Even such a small change can lead to an inexorable weight gain.

The signals of satiety -- that feeling of satisfaction that prompts people to say "I've had enough to eat" -- are influenced not only by the quantity of food consumed but by the specific foods eaten.

Studies show many obese people prefer high-fat foods, foods that are more likely to be stored as fat than the same number of calories from carbohydrates. In this pattern, at least, childhood preferences rather than genetics may be at play.

Finally, many studies have shown that the people most likely to maintain their losses are not those who are the best dieters but those who use physical exercise as a weight-loss aid and continue to exercise regularly after reaching their weight goal.

Exercise is the only nondrug method known that significantly raises the rate at which the body burns calories at rest. Furthermore, exercise itself burns calories, curbs the appetite, relieves emotional triggers of overeating and increases the ratio of muscle to body fat, which in turn raises the rate at which the body uses calories.

Polivy is among several specialists who have come to rely on a nondieting approach to help people achieve and maintain what might be called their predestined, or natural, weight.

"It's time we started treating body weight more like height, as a biologically determined trait," Polivy said. "You don't see short people hanging from door frames trying to stretch themselves out or tall people carrying around heavy weights in hopes of shrinking a few inches."

Whether self-designed or medically directed, diets induce feelings of deprivation that are personally challenging and socially stigmatizing, said Dr. John P. Foreyt, a psychologist who with Dr. G. Ken Goodrick, wrote "Living Without Dieting" (Harrison Publishing, $16.95). "People on diets become obsessed with food, and the obsession itself is counterproductive, often leading to binge-eating."

Morning Call Articles