What's in a diet book?
Often, not much that will help you keep the weight off, concluded nutrition experts who reviewed and rated 13 of America's best-selling diet books.
Three of the books evaluated for The Washington Post were judged "excellent" by the experts: "Jane Brody's Good Food Book," "The New American Diet" and "The Setpoint Diet."
Three were rated "good": "The Bloomingdale's Eat Healthy Diet," "The Rotation Diet" and "The Snowbird Diet."
Three were rated "fair": "The Carbohydrate Craver's Diet," "The Pritikin Program for Diet and Exercise" and "Eat to Succeed."
One was rated "fair" to "poor": The Life Extension Weight Loss Program.
And three were judged "poor": "Dr. Berger's Immune Power Diet," "Fit for Life" and "The Rice Diet Report," which one expert called "dangerous."
These results are not surprising, since dietitians and nutrition researchers tend to be skeptical about weight-loss books -- with good reason. About 100 such guides are on the market, but few offer proof that weight-loss can be maintained long-term.
"If these diet books work, why do we need new ones all the time?" asks American Dietetic Association (ADA) spokeswoman Gail A. Levey, a registered dietitian and nutrition consultant in New York.
Although weight-loss theories have changed frequently in recent years, most experts now agree today that high-carbohydrate, low-fat diets are the best means of both eating well and losing weight, Levey says. Complex carbohydrates (vegetables, grains and beans) are highly nutritious and seem to stimulate the metabolism to burn calories, much as exercise does. They are relatively low in fat and aren't easily absorbed by the body. They are high in low-calorie fiber, which makes the body feel full and helps eliminate wastes.
Research by Judith and Richard Wurtman of the Massachusetts Institute of Technology also has found that consuming too little carbohydrate depletes the brain of the chemical serotonin, which they say is critical to controlling appetite. Serotonin levels that are too low lead to overeating, while small, periodic portions of nonfattening carbohydrates throughout the day help curtail food cravings, they say.
But any weight-loss plan must be accompanied by two other crucial "cornerstones" -- exercise and improved eating habits, says Pat Roginski, a registered dietitian in the District and also a spokeswoman for the ADA. Exercise helps use up excess fat, maintain a high metabolic rate and build lean body mass through muscle, which uses up more calories than the fatty tissue it replaces. Improved eating habits, such as consuming smaller portions and resisting fattening foods, are also vital to maintaining weight loss.
The books rated "excellent" all met several important requirements. They contained nutritionally balanced meal plans, variety and moderation of foods, realistic allowances for gradual behavioral change, clear goals, solid scientific information and reliance on real food over food supplements. Also, they lacked outlandish promises of quick weight loss and reliance on "magical" foods to dissolve pounds.
Many studies have shown that crash diets trigger metabolic responses that make it even harder to keep off fat long-term. "Besides, special foods are distractions," says Dr. C. Wayne Callaway, director of the Center for Clinical Nutrition at George Washington University Medical Center. "They are attempts to sound original."
Reliance on foods with so-called magical qualities are, he says, "the kind of eating patterns you see in people with eating disorders."
Authors of the top-rated books had training in nutrition, led by the wife-husband team of Sonja L. and Dr. William E. Connor, authors of "The New American Diet." She is a registered dietitian (RD) and research assistant professor of clinical nutrition at Oregon Health Sciences University. He is a physician and chief of the division of endocrinology, metabolism and clinical nutrition at Oregon Health Sciences University. He also is a member of the Food and Nutrition Board of the National Academy of Sciences and former president of the American Society of Clinical Nutrition.
This background contrasts sharply with another husband-wife team, Harvey and Marilyn Diamond, authors of the best-selling "Fit for Life." Their credentials came from an unaccredited correspondence school. Robert Haas, celebrity guru and author of popular "Eat to Win" and "Eat to Succeed," received his advanced degree by mail.
Even some relatively sound diet books, the ADA says, contain subtle or blatant nutritional misinformation, or lack effective methods for long-term weight loss. Many have incomplete instructions on proper exercise and necessary behavioral changes. Sometimes, conventional nutritional guidelines masquerade as something new and sensational.
Often diet books are "written with the mask of science and contain a kernel of truth, but that's stretched to the point where it's no longer good science," warns ADA's Levey. Add some gimmicks -- like amino acid supplements which allegedly prevent fat deposits, or not eating after 8 p.m. -- and the result is a diet book that, while not dangerous, may be misleading or ineffective.
An example, according to a recent ADA statement, is "The Rotation Diet" by Martin Katahn, a professor of psychology and director of the Weight Management Program at Vanderbilt University and author of two previous books, "The 200 Calorie Solution" and "Beyond Diet." His book received a "good" rating from The Post's panel.
Although "The Rotation Diet" will promote weight loss, notes the ADA, " 'Eat less fat and walk' is just common sense . . . Katahn, PhD in psychology, uses psychological incentives and the 'crutch' of fixed menus to win the reader over and prompt the dieter to follow the traditional theory of calorie balance. He advocates specific low-calorie meals and daily exercise. This is the mainstay of any successful weight reduction program . . ."
According to the ADA, "The Rotation Diet" also:
Contains calorie levels which are too low to be considered safe for the first and third week of each "rotation," when the female dieter is required to consume only 600 calories for three days and 900 calories for four days.
Does not address the issue of target heart rate (optimal rate for age and physical fitness), "an important consideration for safe exercise."
Teaches very little about long-term moderation and self-control, although it will initiate short-term weight loss "if followed carefully under the supervision of a qualified health professional."
"All of these diets will work short-term, because they induce initial weight loss -- which is water loss," says GW's Callaway. But few will work long term, he says.
Even "the good books lack evidence that they are clinically effective for long-term weight control," contends Dr. William Bennett, author of "The Dieter's Dilemma" (Basic Books, $6.95), which chronicles in detail the problems with fad diets.
"A person picking up these books on a whim is taking a chance," adds Aaron Altschul, director of Georgetown University Medical Center's diet management and eating disorders program. "It is said that people need multiple attempts to lose weight, so if there is no learning in the process, it doesn't count. They go from one trivial book to another."
Sometimes the result is a serious eating disorder, warns Dr. Sue Bailey, medical director of the Chevy Chase Psychiatric Center and the Eating Disorders Clinic of Washington Hospital Center.
"Dieting is a deadly weapon," she says. "There seems to be a real correlation between dieting and eating disorders later on, and I think these crazy diets are part of the problem."
Each new wave of diet books seems to bring a repackaging of an earlier popular attempt, says GW's Callaway. "You see the same gimmicks -- a monotonous diet in which you can't eat but certain types of food, which forces people to lower caloric intakes," he says. "From this they claim special benefits and explain what's happening, but the claim is never really substantiated and they quote people who are long since dead.
"'Fit for Life' and 'The Beverly Hills Diet' are both the kind of eating patterns you see in people with eating disorders, where foods have magical qualities . . . If it sounds too good to be true, it probably is."
One such "magical food" is rice, according to "The Rice Diet Report," which advocates a bland diet of rice and fruit for at least two weeks. Author Judy Moscovitz writes, "after only a few days your appetite largely disappears." She based her plan on the Duke University "Rice Diet" -- which was developed 40 years ago to counteract hypertension, heart and kidney disease and diabetes -- and adapted it for weight loss. However, such a severe 700-calorie eating plan used without strict supervision by a physician is "dangerous," Georgetown's Altschul warns.
An important aspect of many diet books' appeal is the desire to fit a standardized schedule for "average" height and weight, Callaway contends. These sometimes unrealistic goals may result in harmful eating behaviors.
For example, in his work with dieters as director of the Lipid Clinic at the Mayo Clinic from 1982 to '85, Callaway found that two thirds of the women with weight problems were not overeating and, in fact, were eating less than other women of the same size. But "they were often chronic dieters or they skipped meals," he said. "We got them to eat three meals, to exercise a lot and to develop weight goals that were more consistent for them as individuals, not according to some standardized chart."
Does any diet work? "There is not one clear answer yet," says Rudolph Leibel, associate professor at Rockefeller University in New York. Weight is controlled by a combination of variables, he says, including "genetics and environment."
Exercise and behavior change are critical both to losing weight and keeping it off, according to current studies, including one that evaluated clinically administered extremely low-calorie diets at the University of Pennsylvania Medical Center's Obesity Research Group.
Metabolism research is also uncovering information about how the body uses calories and can shed weight. New "weight recycling" studies by Thomas Wadden and his colleagues in the University of Pennsylvania's group have found that very obese people who lose weight lower their metabolic rate and consequently require less food to maintain their body weight, a condition known as "the starvation response." When they stop dieting, the consequence is often dramatic weight gains because their metabolism has slowed down. Their bodies have become more efficient in using food and burn calories slower.
For the average dieter, says Wadden, "it looks like you'd be much better off to consume a 1,000- to 1,200-calorie diet and take your own time to lose the weight."
Does this mean give up and get fat? No, but with knowledge of their body's individual quirks, people often are capable of devising their own effective diet plan.
"I tell people to cut down on or cut out unnecessary calories -- like alcohol, sweets and fats -- and set up in their heads three columns of food -- normal, better and best," says Gail Levey. "That means, for example, whole milk is 'normal,' 2 percent milk is 'better' and skim milk is 'best.' "
Add to this exercise and, if you have lots of weight to lose, guidance and support of a professional counselor, she adds. "You can lose 50 pounds this way. A lot of your success has to do with your mindset."
Janis Johnson, a free-lance writer based in Philadelphia, frequently writes for Health.