According to research team at Johns Hopkins Medical School in Baltimore, very few weight-loss programs work and people should carefully choose a program to maintain weight in long term. A review of 4,200 studies has been conducted by medical experts in order to find out evidence of the effectiveness of weight-loss programs. It has been found that very few programs out of more than 32 commercial weight loss programs are helpful.

According to Kimberly Gudzune, research lead, "Primary care doctors need to know what programs have rigorous trials showing that they work, but they haven't had much evidence to rely on. Our review should give clinicians a better idea of what programs they might consider for their patients".

It has been found by the researchers that out of 32 major commercial weight-loss programs marketed throughout nation, just 11 have been studied thoroughly in randomized controlled trials.

The researchers found that of these studies, only two programs are supported by gold-standard data. It indicated that participants, on average, were able to lose more weight after one year in these programs. The researchers wrote that clinicians could think of referring obese or overweight patients to Weight Watchers or Jenny Craig.

Other programs, like NutriSystem, also show good weight-loss results. However, more studies evaluating long-term outcomes are required to be conducted. The new research was a face-lift to a survey from 2005. That survey took a glance at the feasibility of business health improvement plans.

In September in 2014, the earlier study was published in the Journal of the American Medical Association. It was found that low-carb and low-fat diets in branded weight loss programs also work well. These weight loss programs are suggested through books, or in-person or online.