The study was carried out by scientists from Johns Hopkins University School of Medicine, and their findings have been published in the Annals of Internal Medicine. The purpose of the study was to provide reliable information to doctors and clinicians, who are not sure which diet plans they should advise overweight and obese patients to follow.
“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,” says Dr. Gudzune, an assistant professor of medicine at the Johns Hopkins University. “Our review should give clinicians a better idea of what programs they might consider for their patients.”
According to Science Daily, the project involved a review of some 4,200 trials of 32 of the major commercial weight-loss programs. The data came from medical literature databases and the weight-loss programs themselves. The studies involved participants who had followed a diet plan over at least a 3 month period and up to 1 year.
The researchers point out that two-thirds of U.S. adults are overweight or obese, and nearly two-thirds of adults say they have tried to lose weight. In 2014, weight-loss programs were a $2.5 billion-per-year business in the US and it is expected to keep growing.
But, the research revealed that the vast majority of these commercial programs showed no evidence for their claims of success, either for reducing weight or keeping it off – even though many charge between $570 and $682 per month for participants to buy replacement meals.
The team discovered that only 39 trials had ever been carried out on just 11 of all the weight-loss programs available.The overwhelming majority of the programs had never undergone testing in strict clinical trials and very few of those that had, met the scientific gold standard of reliability.
Therefore, says Medical News Today (MNT), the researchers decided to only include randomized controlled trials in the study, in which participants were assigned to either a commercial weight-loss program or a less comprehensive intervention.
Studies of these programs, it said, lasted for at least 1 year, and could prove that participants lost more weight than people who dieted alone or only received health information or weight-loss counseling.
In the end, Weight Watchers and Jenny Craig proved to be the most effective programs for long-term weight loss. The success of these “high intensity programs” appears to be down to a combination of self-monitoring, goal setting, nutritional information and counseling.
Science Daily reports that this also included NutriSystem, which showed similar results over a 3 month period, but lacked any longer term trials to prove if they were successful over a longer period.
The research also included other categories such as low-calorie, meal replacement programs, the Atkins, low-carb, high protein diet, and four self-directed programs.
The former involved HMR, Medifast and OPTIFAST and, although, they showed that participants lost more weight than control groups after 4-6 months, the only long-term study failed to prove any gains after 12 months.
The self-directed programs – SlimFast, the Biggest Loser Club, eDiets and Lost It! – met the gold standard of medical research, but the researchers said they could not make any firm conclusions about their effectiveness.
On the other hand, the researchers said that the trials of the Atkins diet “appear promising,” showing that participants lost more weight at 6 and at 12 months, than people receiving just counseling.
On the John Hopkins’ website, Dr Gudzune advised that, “Clinicians could consider referring patients who are overweight or obese to Weight Watchers or Jenny Craig.”
However, even here, MNT says “the team cautions that, although Weight Watchers and Jenny Craig were found to be the most effective commercial weight-loss programs, the weight loss was still “modest,” with participants losing around 3-5% more than control participants.”
The team says that more rigorous research over a longer period is required. Jeanne Clark, M.D., M.P.H., the Frederick Brancati, M.D., M.H.S., Endowed Professor of Medicine, director of the Division of Internal Medicine and a study co-author said, “losing weight for three months, then regaining it, has limited health benefits. That’s why it’s important to have studies that look at weight loss at 12 months and beyond.”
