Which Diets Really Work?

The Daily Beast’s resolution for 2010: Your diet should work. So we crunched the numbers, using clinical studies, for the ultimate rankings of weight-loss effectiveness.

01.03.10 10:49 PM ET

Diet commitments follow New Year’s as surely as New Year’s follows Christmas. For most people, however, what then follows is equally predictable: diet failure.

So The Daily Beast made a resolution for 2010: Let’s figure out, as definitively as possible, which diets really work. We took the largest, most recent clinical studies for the nation’s most popular diets, and compared the raw data using consistent criteria: six-month and 12-month figures for weight loss and participant retention, as well as 12-month change in Body Mass Index. (The last time, as best we can tell, that anyone undertook a similar exercise was back in 2007 by Consumer Reports, but they did not measure for BMI changes.) In doing so, we were able to find some clear differentiations in terms of which of 10 popular diets work better than others.

The answers were surprising. Mainstays like Jenny Craig and the Zone fared relatively poorly, while Atkins and the Mediterranean diet did well. The No. 1 diet overall? The answer may surprise you.

Gallery: Most-Effective Diets

“To me, a diet is something that you count the days until it’s over and you miss the big picture,” says Dr. Connie Guttersen, nutritionist and author of The Sonoma Diet. Guttersen says a diet should instead be “a way of eating that becomes a lifestyle.”

Susan B. Roberts: 10 Ways to Lose 10 Pounds FastExperts agree that the most effective diets are feasible over an extended period of time, but there’s not a single solution for the entire population. “What I believe makes a diet ‘effective’ is that you can stay on it and that your body feels good on it. This will not be the same for each person,” says Brooke Castillo, a weight-loss coach and author of Why Can’t I Lose Weight? “Any diet that makes you feel hungry (liquid shakes) or tired (Atkins) may work temporarily, but won't last long-term because they put you at war with your own body… cooperation with our bodies is what lasts.”


To compile our rankings, we combed journals of medicine and nutrition and university publications to find clinical studies on specific diets that included six-month and 12-month figures for weight loss and participant retention, as well as 12-month change in BMI. Each category was equally weighted at 20 percent of the total rank for each diet. In instances where one category was unavailable, the remaining categories were weighted at 25 percent. If there was more than one recent clinical study available, we used the data with the greatest number of participants.

Additionally, while we didn’t include nutrition in the ranking calculation, we recorded the dietary quality of diets when available, based on the clinical study “A Dietary Quality Comparison of Popular Weight-Loss Plans, “ published in the Journal of the American Dietetic Association in October 2007.

In an effort to keep the data as consistent as possible, some popular diets, such as the South Beach and Abs diet, are absent from the list due to lack of published, long-term clinical studies.

Plus: Check out Hungry Beast for more news on the latest restaurants, hot chefs, and tasty recipes.

Lauren Streib reported and wrote this article.