Irritable Bowel Syndrome Message Boards | Consumer Reports on Popular Diets

Rating the diets from Atkins to the Zone:

With two-thirds of American adults now overweight or obese, the need for effective weight-loss diets has never been greater. But it's hard to know where to turn amid the sea of promises and glowing "results not typical" testimonials. Now Consumer Reports has taken the wraps off nine popular diets.

Using a powerful nutritional-analysis database, we calculated the calorie counts and nutrient composition of a week's worth of menus from each plan. We checked whether the diets conformed to the 2005 U.S. dietary guidelines, which our experts agree represent the current best advice on long-term healthful nutrition. To evaluate the diets' effectiveness--how much weight people actually lost and how many people were able to stick to the diet--we conducted a comprehensive review and synthesis of published clinical research. (We plan to update our analysis whenever new studies are published.)

The Ratings identified some diet winners and will help you choose one that makes sense for you. Among our findings:

Carbs, schmarbs. One of the top-rated diets, Weight Watchers, pointedly ignores the low-carb fad. It recommends even more carbohydrate calories than the typical American diet contains, with heavy emphasis on fiber from whole grains, fruits, and vegetables And it keeps fat calories to less than a quarter of the total. Weight Watchers had the best overall adherence rate of any that we studied.

Drink your diet. Slim-Fast, a commercial diet that replaces parts of two meals a day with its shakes or bars, rated favorably on the strength of its strong short-term weight-loss results and balanced
nutrition. But its high long-term dropout rate suggests that after awhile, people may tire of its limited menu.

What about Atkins? The Atkins diet worked very well in the short term, with results at least as good as our other top-rated diets. But its nutritional deficiencies--too much fat and saturated fat, too little fiber, too few fruits--depressed its overall Rating and might have a negative effect on some dieters' health.

Popular but unproven. The much-touted South Beach and Jenny Craig diets still lack scientific data to back up their claims. The South Beach Diet has been studied in two clinical trials that lasted just three months each, so we couldn't rate its overall efficacy. Jenny Craig offers good nutrition, but it has never been studied in a clinical trial.

Online: More info needed. We could not rate eDiets.com, the largest online diet site, because the only available research study was too small for us to rely on its results.

Our review of the diet studies also confirmed the value of four key techniques that should help you stick to any diet, including one you devise yourself.

COMBATing DIET DROPOUT

"The best diet is the one you can stay on," says Cathy Nonas, R.D., M.S., a longtime obesity researcher who heads the obesity and diabetes program at North General Hospital in New York.

As researchers have repeatedly found, the inability to adhere to diets is the main barrier to permanent weight loss. For example, researchers randomly assigned groups of 40 overweight volunteers to follow either the Atkins, Ornish, Weight Watchers, or Zone diet for a year, in a Tufts-New England Medical Center study published in the January 5, 2005, Journal of the American Medical Association. In the first two months, 21 percent of dieters dropped out; by the end of the year, 45 percent of them had quit.

Moreover, even the volunteers who stuck with the study didn't follow their diets very strictly. The Atkins people were supposed to be consuming no more than 30 to 35 grams of carbohydrates per day. After a month on the diet, they were eating about twice that much, on average. Those people assigned to the ultra-high-fiber Ornish diet ended the year consuming, on average, about as many grams of fiber per day as they had been before they started the diet. Regardless of the assigned diet, the average participant in the study didn't come close to the modest benchmark we had set for successful weight loss after one year: a weight reduction of at least 5 percent.

On the other hand, staying on a diet and losing a significant amount of weight is not impossible. In that same Tufts study, the participants who followed their prescribed diets the most faithfully shed the most weight. Our own survey of some 32,000 dieting Consumer Reports subscribers, published in our June 2002 report on diets), found that nearly a quarter managed to take off at least 10 percent of their starting weight and keep it off for a year or more. That is a weight loss that scientific research shows will markedly reduce the long-term risk of obesity-related ills such as diabetes. And five of the nine diets we analyzed for this report have at least one published study showing that people who stayed on the diet for at least six months lost more than 5 percent of their starting weight.

Adherence is important for another reason, too: To maintain lost weight, dieters must permanently reduce their calorie intake because they will need fewer calories to fuel their now-smaller body. That's why the best weight-loss diet is one that you can follow for life.

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