Philadelphia ? A review of 10 of the nation’s most popular weight-loss programs found that except for Weight Watchers, none of them offer proof that they actually work at helping people shed pounds and keep them off.

Only Weight Watchers had strong documentation that it worked — with one study showing that participants lost around 5 percent (about 10 pounds) of their initial weight in six months and kept off about half of it two years later.

However, the researchers who conducted the review published in today’s Annals of Internal Medicine stressed that the lack of scientific evidence should not be viewed as an attack on diet programs.

“There are no data on weight loss when you go to a health club, either,” said Thomas Wadden, a University of Pennsylvania weight-loss expert and the study’s co-author. “We hope that doctors and patients will use this information to make more informed decisions.”

The review aimed to replace glossy ads and dramatic testimonials with information about program components, safety, staff qualifications, cost and effectiveness — and should serve as a call to programs to conduct more strenuous research, Wadden said.

The authors of the latest review could not find any published evaluations about Jenny Craig Inc. of on self-help programs like Overeaters Anonymous and Take Off Pounds Sensibly.