About 45 million Americans go on slimming diets each year, spending roughly $2 billion on the 10 most popular commercial programs, according to a University of Pennsylvania study published in the Annals of Internal Medicine. Yet researchers who reviewed the top-selling methods available in 2004 found that most have not been subjected to rigorous clinical testing.
A team led by Michael Dansinger of Tufts-New England Medical Center in Boston compared four programs over one year: Weight Watchers, the low-carbohydrate Atkins diet, the vegetarian Ornish plan, and Zone, which targets macronutrient and glycemic balance. The findings appeared in the Journal of the American Medical Association.
Results across all four were modest. One in four participants shed at least five percent of their starting weight, but the Atkins and Ornish programs recorded particularly high dropout rates. Weight Watchers was the only plan to have undergone credible clinical trials beforehand, with 423 participants, results published in JAMA in 2003.
More than 1,000 diet methods were being promoted in American media at the time, most without supporting evidence. Dr. Robert Eckel of the University of Colorado emphasized that prevention through careful dietary choices and regular physical activity remains the most effective approach to avoiding obesity in the first place.
Historical summary. TurkishPress restated this AFP wire report, first published in January 2005, in its own words.