According to a new report, millions of Americans choose commercial weight-loss programs in order to shed excessive pounds. But still little scientific evidence is there to show whether these plans can help keep weight off for the long-term.

According to experts, only two out of 32 major commercial weight-loss programs marketed nationwide have scientific evidence to show that their clients maintain weight loss for minimum a year. As per researchers, the two that have evidence are Weight Watchers and Jenny Craig.

The study was published in Annals of Internal Medicine. The study authors indicated that two-thirds of adults in the US are overweight or obese and it increases risk for high blood pressure, type 2 diabetes and heart disease. As per background information in the study, weight-loss programs in the US were a $2.5 billion business last year. According to the study, Jenny Craig has about 13% of the market and Nutrisystem has about 14%.

"Because I'm looking for the health benefits associated with sustained weight-loss, I feel more comfortable recommending a program to a patient that's been scientifically proven to work", said Dr. Kimberly Gudzune, lead author and an assistant professor of medicine and a weight-loss specialist at the Johns Hopkins University School of Medicine.

About 4,200 studies have been reviewed by the researchers. They found randomized, controlled trials for 11 of the 32 major weight-loss programs. The programs involved Jenny Craig, Health Management Resources, Weight Watchers, Nutrisystem, The Biggest Loser Club, Medifast, eDiets, Lose It!, and SlimFast.

The researchers said that for those 11, only Weight Watchers and Jenny Craig had gone through studies and showed that people lost weight as well as kept it off for at least a year. It has been found by the researchers that Weight Watchers and Jenny Craig are effective for helping people lose weight and keep it off.