A New Look At Weight Loss

By: Lisa Sanders, M.D.

For the past several years, I've been working with a team of researchers at Yale and Stanford Universities. We've conducted a systematic analysis of hundreds of weight-loss studies dating back to the turn of the last century. Initially, we were looking at whether low-carbohydrate diets, such as the Atkins diet, were any better or worse than other types of diets. That study was published in the Journal of the American Medical Association (JAMA) in 2003. Now we're looking at the drugs used in dieting. In the course of my research, I have read literally hundreds of studies on the effect of different diets on weight loss and other aspects of health. After years of sifting through these studies, I was struck by a surprising pattern that seemed to defy conventional medical wisdom: All these diets did work -- for some people.

Time after time, a study would show that a diet worked rather dramatically for, say, 10, 20, even 30 percent of the people who tried it. How is it that nearly every good diet had winners and losers? Each seemed to have a cadre of people for whom the diet worked wonders, while other dieters failed miserably.

I became intrigued by the possibility that there was no single diet that worked for everyone but, rather, different diets that worked for different people.

Perhaps the key to weight loss was not the single best diet, or the most motivated person who was trying to lose weight -- though clearly, diet and motivation are important. Perhaps the key lies in matching the right dieter to the right diet.

One of the conclusions of my research, and the research of many who came before, is that there are aspects of any diet that help predict how well it will work. For example, the lower the calorie content of the diet, the faster you will lose weight. And the longer the diet lasts, the more weight you will lose. But I realized that the key to eating fewer calories and staying on that diet depends on which diet and which individual.

This realization led me down a new path of inquiry: How could we use what we now know about weight loss to do for dieting what is already being done in other areas of medicine? More specifically: What list of questions would let you figure out which diet will work best for you? The search for that questionnaire was the genesis of the Perfect Fit Diet.

For the past year, I've been working to distill my research findings and extrapolate my clinical experience in treating overweight patients into a comprehensive questionnaire that anyone could complete. The questions range from simple "driver's license" information, such as age, gender, weight, and medical and family history, to detailed questions about lifestyle, eating habits, and dieting history.

Once you've completed and scored your self-test, you'll be able to choose a weight-loss diet that best fits you and then further customize it based on specific aspects of how you eat, how you live, and how your body works. The Perfect Fit Questionnaire takes an hour or so to complete, but the results will save years of searching for the right diet.

The Perfect Fit Questionnaire will:

The Perfect Fit Questionnaire is a direct translation of the doctor-patient Q&A I've been using to design personalized weight-loss plans for my patients. The answers to this questionnaire will empower aspiring dieters -- whether obese or merely overweight -- to successfully lose weight and keep it off, despite previous failed attempts.

Why Taste Matters

The Perfect Fit Diet is a customized dieting strategy built around your life and your preferences. In recent research, food preference has emerged as a key factor in satisfying hunger, and thus, in dieting success. (Nutritionists who work with people with diabetes have led the way in recognizing the importance of structuring a diet that works with a dieter's individual tastes.)

The Perfect Fit Questionnaire systematically uncovers what makes you eat, what tastes good to you, what relieves your cravings, and what makes you feel satisfied. It incorporates that information into a personalized diet plan that will let you lose weight and maintain your ideal weight -- because it's a satisfying eating plan that's a perfect fit for your lifestyle, your food preferences, your satisfaction -- in short, a perfect fit for you.

Doctors, and just about everyone else, have thought of food preference as something trained and therefore malleable. If you wanted to lose weight, you would learn to love broccoli. If you couldn't, then you weren't serious about weight loss. Science is beginning to show us how little of food preference is really learned behavior and how much is in our genes.

Recent research here at Yale reveals that what we think of as food preference or taste is actually a complex variety of factors, both genetic and acquired, physical and emotional. One of the most interesting findings is that some foods taste very different from one person to another, and that this sensibility exists on a genetic level. For example, some people have tastebuds that are keenly sensitive to even a trace of bitterness, and to them, vegetables like broccoli and Brussels sprouts and fruits like grapefruit can be extremely unpalatable.

In experiments, researchers have used a chemical called 6-n-propylthiouracil, or PROP for short, to test for this trait. Some people can detect even a trace of this chemical, while others cannot taste it at all. And it runs in families. If one of your parents has the ability to taste PROP, there's a good chance that you will have it too.

Researchers at the National Institutes of Health recently identified a gene, called TAS2R, on chromosome 7. There are five forms of this gene, and which one you inherit determines whether you can even detect this bitter taste or to what degree you are sensitive to it. If you inherit a high degree of sensitivity to PROP from both parents, you will be able to taste even the tiniest amount of it. If you can taste PROP, then you may not be able to enjoy broccoli, because it simply tastes bitter to you. This means that hating vegetables may not be so much a moral failing as it is a genetic trait, like hair color or the presence of freckles.

That's just one reason why accommodating individual food preferences is so important to a successful diet. My research, and that of others, shows that the primary predictor of a dieter's success is longevity: The longer you can stay on your diet, the more weight you'll take off and keep off. Deprivation diets only work in the short run; you can only stay on a diet that satisfies your fundamental food cravings. Unless your diet reflects your individual food preferences, it can't be sustained -- because it won't be satisfying. The Perfect Fit Diet is the first weight-loss program that respects this immutable law of human nature.

The bottom line of the new science of dieting is clear: If you can customize a diet to reflect your individual profile -- your genes, your metabolism, your lifestyle, and your food preferences -- you can stay satisfied, and stay on your diet.

That's how you lose weight, and that's what this book is all about.

(Reprinted from The Perfect Fit Diet: Combine What Science Knows About Weight Loss With What You Know About Yourself by Lisa Sanders, M.D. (Rodale Inc., Hardcover, $24.95). Permission granted by Rodale, Emmaus, PA 18098. Available wherever books are sold.)

© 2004 Lisa Sanders, M.D.

Lisa Sanders, M.D., is an internist practicing in Connecticut and is on the faculty of Yale University School of Medicine. In her research and practice, she specializes in the treatment of overweight and obese patients. Before entering medical school, she was an Emmy Award-winning producer at CBS News, where she covered medicine and health. Her widely read "Diagnosis" column appears monthly in The New York Times. Dr. Sanders lives in New Haven, Connecticut, with her husband and two daughters.

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