Top Diets 2004: The Skinny About Diets

What works when you want to lose weight? Here's what the experts say--plus how our testers fared on the most popular diets.

Contributing editor John Pekkanen has been covering medical issues for 30 years. He's won two National Magazine Awards for Washingtonian stories.

Reading the statistics on weight loss is enough to drive a dieter into the arms of a pastry chef. At any one time, half the nation's men and two-thirds of the women are trying to lose weight. The more we try to lose, the more we seem to gain. Nearly two-thirds of adult Americans are overweight or obese, say the Centers for Disease Control and Prevention. We've gained, on average, nearly eight pounds apiece since 1986.

We pay a price–$61 billion a year on medical treatment for obesity and its complications, plus another $50 billion a year feeding the weight-loss industry–diet centers, low-cal foods, health clubs.

The American Obesity Association estimates that being obese is linked to 300,000 premature deaths a year, making being overweight a health problem rivaling smoking.

*There are more than 4,000 books on diets and dieting, and publishers keep churning them out, each one touting another "weight-loss revolution."

To find out if some diets work better than others, a Tufts University study randomly divided overweight volunteers ranging in age from 22 to 72 into four groups of 40. Each group agreed to try one of four popular diets for a year with no required lifestyle changes. The four diets:

*Atkins. A high-fat, high-protein, low-carbohydrate diet that specifies eating meats, cheeses, eggs, poultry, fats, and oils and restricts carbohydrates such as grains, fruits, and vegetables.

*Ornish. Everything the Atkins diet isn't. A very-low-fat diet that specifies eating lots of complex carbohydrates as well as very little meat, dairy, or fat.

*Zone. A diet that calls for eating the "right foods." This includes 40 percent carbohydrates,30 percent protein, and 30 percent fat.

*Weight Watchers food plan. A low- to moderate-fat diet that emphasizes portion control and calorie restriction by assigning a point value to foods.

Presented at an American Heart Association meeting last fall, the Tufts study concluded: If you're trying to lose weight, it doesn't matter which diet you follow.

On average, the participants lost about the same amount of weight, whether on Atkins or Ornish or something in between.

Although some who remained in the study for the full 12 months lost as much as 10 percent of their body weight, on average the subjects lost only 5 percent of body weight.

*Those results don't surprise Dr. Arthur Frank, medical director ofthe George Washington University Weight Management Program.

"It doesn't matter if you're on a low-fat diet or a high-fat diet or a low-carb diet," says Frank. "What matters is how many calories you consume." He says many diets help take off weight because they are "gimmicks" that make people pay attention to what they eat so they eat less.

Dr. Michael Dansinger, lead investigator on the Tufts study, found that participants who stuck with their diets for the full year improved their cholesterol levels, reducing their heart-attack risk estimates up to 15 percent.

Frank says weight loss will improve cholesterol levels, regardless of the type of diet. He challenges the notion that the high-fat Atkins diet actually reduces cholesterol levels. After weight stabilizes on the Atkins diet, Frank contends, continued consumption of high-fat foods to maintain weight loss will probably increase cholesterol levels.

The Tufts study also found what many veteran dieters already know–that weight-loss diets of any kind are very tough to maintain, and extreme diets are even more so. Only about one quarter of the participants stuck closely with theirdiets for the full12 months. For a weight-loss program to be successful, it must be long-term.

Most diets are self-defeating because people think of them as "temporary measures" to drop some pounds rather than as a "lifelong eating strategy" to maintain a healthy weight, says Dansinger. When people achieve a desired weight by dieting, they often declare victory and return to their old ways of eating, only to regain the weight.

We are often told that the best way to lose weight is to "eat sensibly." But what does that mean?

For years, the federal government has told us to cut down on fat consumption. Average fat consumption has dropped slightly. Yet obesity has increased.

The US Department of Agriculture's "food guide pyramid" says that the key to a healthy diet is to eat fats, oils, and sweets "sparingly" while vegetables, bread, cereal, rice, and pasta can be eaten almost at will.

The problem with this advice, says Dr. Walter C. Willett, chair of the Department of Nutrition at the Harvard School of Public Health and author of Eat, Drink, and Be Healthy, is that it's wrong.

Willett contends that labeling all fats and oils as bad and all fruits and vegetables as good is doing us harm. He says that certain fats and plant oils–including olive, canola, soy, corn, sunflower, and peanut oils as well as the oil in avocados–are healthful.

Some vegetables are unhealthful. Take the potato, the most widely consumed vegetable in America. Willett says the body breaks down glucose in potatoes almost as fast as it does pure sugar. The result is a rapid spiking of blood-glucose levels that makes us hungry sooner and puts us in jeopardy of developing Type II diabetes.

Willett turns the pyramid on its head. He puts the "white diet"–white potatoes, white rice, white bread, white pasta along with red meat, butter, and sweets–in the "use sparingly" section while urging the consumption of good fats along with most fruits, legumes, and vegetables. He says the coarser the grains the better, because they are digested more slowly and produce steady blood-glucose levels. He says fish, poultry, and eggs can be eaten up to twice a day.

Willett believes that women have been misled into believing they should consume lots of calcium-rich diary products to ward off osteoporosis. He finds no evidence of insufficient calcium intake and argues that women mostly get unwanted fat and calories from dairy products.

*The secret to losing weight is simple: Burn more calories than you consume. Would that it were so simple.

To keep off weight, Frank says, we have to override the "regulating system" that causes us to overeat. Frank has seen a number of patients succeed. The key is to focus on the long term. Dansinger says any weight-loss program should be approached with the mindset that you're looking for a "lifelong match."

Alexandria dietitian Hope Warshaw notes that Washingtonians face an additional challenge–restaurant meals. In a city of two-career couples, dining out isn't just an occasional luxury. The problem is that we too often approach restaurant meals with "a special-occasion mentality."

"People can eat healthfully in 99 percent of the restaurants they go into," Warshaw says. In her book Eat Out, Eat Right, she suggests such strategies as splitting or sharing entrées so that you have less food in front of you. Starving all day so you can then indulge at dinner is not good, she adds. Not only are you more likely to overeat as a result, but not eating regularly can slow your metabolism.

Which brings usto the missing ingredient in most diets: regular exercise, which speeds up metabolism and helps the body burn calories more quickly.

Although Frank and Dansinger have treated patients who have lost and kept it off without exercising regularly, that's the exception. Exercise, says Frank, makes losing and maintaining weight easier.

One final piece of advice: Keep trying. Frank says that almost everyone who ultimately succeeds in long-term weight loss has failed before.

*We tested five strategies for losing weight. Three of our experimenters went on popular diets: the Atkins diet, the South Beach diet, and the Weight Watchers plan. The fourth adopted a vegan diet. The fifth maintained her normal eating habits but began working out with a personal trainer.

We asked each person to dine out as often as he or she normally would, then report on how easy or hard it was to stick with the regimen as well as how much weight each lost. Here are their stories.