Keeping It Off : Maintaining: Scientists have come up with a number of theories about why dieters’ weight always seems to come creeping back.
Backsliding is almost universal among dieters. It leaves feelings of frustration and failure--along with a fresh layer of fat.
But weight-control experts are finally focusing on the mysteries of maintenance. Studies indicate that enzymatic changes in a dieter’s body may be partly responsible when pounds creep back. Other findings suggest that the tendency to be heavy and regain pounds easily is etched in the genes. While you can’t change the biological and genetic forces that conspire to put pounds back on, there’s plenty you can do to fight them.
For some time, scientists have grappled with the question of why some bodies gravitate toward leanness while others tend to be heavy. Much research has focused on the “set-point” theory--the idea that after pounds are shed, the body inexplicably will return to a specific weight.
One explanation offered for set points stems from various studies that found that a dieter’s metabolism tends to decelerate during dieting and remain slowed even when normal eating is resumed. This would mean that calories are burned more slowly, allowing weight to creep up easily.
New research disputes this widely accepted phenomenon, however. In one study, obese women who lost weight did experience significant drops in resting metabolic rate (RMR) while dieting, but their RMRs did not remain low.
“Our study, which monitored metabolism over the course of a year, indicates that once you’ve stopped dieting and achieved a stable body weight, your RMR increases to a level that’s appropriate for your new weight,” says the study leader, Thomas A. Wadden, associate professor in the department of psychiatry at the University of Pennsylvania School of Medicine in Philadelphia.
However, he cautions, this doesn’t mean RMR will soar back up to pre-diet levels, “so to maintain a lower weight, you will have to watch your calorie intake carefully.”
The latest research into the mechanisms that may stymie weight maintenance involves lipoprotein lipase (LPL), an enzyme in fat tissue thought to contribute to obesity in two ways. First, it extracts triglycerides (fats) from blood and converts them into a form in which they can be stored in the fat cells, which plumps them up. Second, animal experiments suggest that LPL may signal the central nervous system to stimulate increased food consumption.
It’s no surprise that obese people tend to have high levels of LPL. But what is startling is that dieting doesn’t cause their LPL levels to drop. In fact, weight loss may make their LPL levels surge.
Dr. Philip Kern and colleagues at Los Angeles’ Cedars-Sinai Medical Center put nine obese men and women (average weight: 300 pounds) on a supervised very-low-calorie diet. The subjects shed an average of 93 pounds in six to nine months. LPL was measured at the start of the study and after each subject had maintained the weight loss for three months. All of their LPL levels had increased significantly. The heavier they were to begin with, the greater the rise in LPL. Kern thinks that their LPL levels rose to nudge their bodies into reestablishing an obese state.
Kern’s findings may help explain why the formerly obese find it so tough to keep off pounds. But does LPL hinder the dieting efforts of those with comparatively little to lose? Probably not, Kern speculates. He believes there is a “threshold of weight” that needs to roll off before LPL activity increases.
It’s unclear what that threshold, if it exists, might be. Kern speculates dieters would have to drop 10% to 15% of their body weight for LPL to kick in (his subjects lost 15% to 50%, though the exact threshold probably varies among individuals).
Still, normal-weight folk who lose a few pounds often put them back on as easily as obese people do, and two recent studies may provide some clues as to why. Though neither focuses on weight maintenance per se, they do reveal that the tendency to sustain a particular weight may be hereditary.
In one of the studies, scientists at the University of Pennsylvania in Philadelphia compared the lifelong health records of 93 pairs of identical twins who were raised apart. They found that genetic factors were twice as important as childhood environment in determining adult weight.
A study conducted by Claude Bouchard and colleagues at Laval University in Quebec yielded similar results. Twelve pairs of male identical twins, average age 21, were put on a three-month overfeeding program. Six days a week, each twin was fed 1,000 calories over the amount he normally consumed.
All 24 men gained--up to 29 pounds--and all experienced an increase in body-fat percentage and, specifically, in estimated subcutaneous fat (located just beneath the skin and thought to increase the risk of diabetes and heart disease).
But there was three times as much similarity in the weight-gain pattern of each pair as of the group as a whole. If one man put on an extra 10 pounds, for example, his twin gained about 10 as well; and if most of the extra weight wound up around his belly, his brother’s added layer of fat also formed there.
While genetic factors can strongly influence weight, a tendency to put on excess pounds can be overcome. The struggle may soon get easier, in fact, because experts are focusing more and more on how to help people keep those pounds from reappearing.
According to Sandra Haber, a psychologist in New York specializing in food issues, successful maintenance starts with a sensible weight-loss plan. Most people consider dieting a temporary measure, she says. “They deny themselves food on the basis that the diet won’t last forever.”
However, being hungry and passing up favorite foods creates a sense of deprivation. When restrictions are released, there’s a natural tendency to overcompensate. Add that to a hereditary or behavioral tendency to gain back the weight, and the diet is almost bound to fail.
Though you may not be able to quash the biological imperative that pressures you to put the pounds back on, you can control habits and attitudes that affect weight gain.
“I ask people to rate foods on a scale of one to 10, with the 10s being those they like best,” Haber says. “Together we design an eating plan that includes sevens through 10s in healthy amounts.”
She feels a structured approach works best. “If you like ice cream, try this: After dinner, go to the ice cream store, buy a small cup of your favorite flavor, eat it, then take a walk. You’ll burn calories, your desire for the ice cream will be satisfied and, most important, you will be in control of the entire situation.”
Successful dieters who are serious about sustaining their svelter selves might want to buy a copy of the “Weight Maintenance Survival Guide” (Brownell & Hager: 1990) by psychologists Kelly Brownell of the University of Pennsylvania School of Medicine in Philadelphia, and Judith Rodin of Yale University. (Call (800) 736-7323 to order; the book costs $19.90, including shipping and handling.)
Brownell and Rodin outline strategies that should be familiar to any dieter, such as learning to recognize real hunger and keeping a healthy fat-protein-carbohydrate ratio.
They also stress the importance of exercise to weight maintenance. They cite a study that compared the exercise habits of women who put pounds back on after dieting with those who kept them off. About 92% of the maintainers said they worked out regularly, while only 34% of the regainers claimed to exercise.
Brownell and Rodin point out that you don’t have to sweat buckets to burn calories. A daily brisk walk will do. What’s more, they write, “Each time you exercise, no matter how you do it, you are sending a signal to your self-esteem that you are making positive changes.”
Their bottom-line advice is to make the same commitment to maintenance that you made to dieting. For example, periodically you may keep a written record of what, when and how much you eat and how you feel while eating--an exercise routinely used by fledgling dieters. Brownell and Rodin liken this practice to having regular medical checkups, which “will allow you to nip problems in the bud . . . and also show you how many positive changes you have made.”
The book includes guidelines for building self-esteem, avoiding deprivation, using social support and thinking positively. If you pig out, for instance, instead of berating yourself, Brownell and Rodin suggest you find a way to remedy the situation and assuage your guilt, perhaps by planning extra-long walks for the next few days.
Being able to turn a potential post-diet disaster into a positive occurrence is one way of taking control of eating--and maintaining a hard-earned, healthy weight.
