Recently a paper was published in the Annals of Internal Medicine that compared national commercial weight loss programs to try and find which produced the best, long term results. It compared 4212 different studies and concluded that Weight Watchers and Jenny Craig produced weight loss that persisted beyond 12 months.
Why this study was done
The Affordable Care Act (ACA) will likely expand insurance coverage to 25 million previouslt uninsured Americans. People who get insured through the exchanges get coverage for a range of preventative services including obesity screening and counseling. That said, there are no guidelines on what doctors should prescribe. This study is an attempt to guide clincians on what they should recommend. It builds on a study conducted in 2005 that concluded that Weight Watchers was the only program with demonstrated weight-loss efficacy.
What programs were selected
The researchers generated a list of 141 proprietary weight-loss programs. Then they culled the list based on a range of criteria. Programs that qualified had to focus on dietary change, behavioral counseling or social support, did not promote medications or supplements and were nationally available. This left 32 programs to be studied. Well known programs include Weight Watchers, Jenny Craig, Nutrisystem, HMR, Medifast, OPTIFAST, Atkins, The Biggest Loser Club, eDiets, Lose It! and SlimFast.
How data was collected
The researchers included randomely controlled trials (RCTs) of overweight or obese results that compared a weight loss program and a control. These trials had to last for at least 12 weeks. The researchers also included RCTs without controles that lasted at least 12 months.
How these data were analyzed
The analysis was done by calculating and displaying the between-group mean differences with 95% confidence intervals for individual RCTs. These mean differences were then qualitatively compared between studies.
The results what they mean
The key takeaway is that Weight Watchers and Jenny Craig were the only programs that produced weight loss that was sustained past 12 months. That said, there are a few things to note when interpreting these results
#1: The magnitude of average weight loss is not huge
The range of 3 month weight loss observed for Weight Watchers is 2.7%-5.9%. At 12 months this drops to 2.6%-3.2%. For Jenny Craig observed weight loss was higher, 7.5% at 6 months and 6.4% at 12 months.
#2: Most of the programs failed because they didn’t have the studies, not because of efficacy
Nutrisystem, the 3rd largest competitor in weight loss, shows weight loss in the short term, but fail to be recommended by this study because of a lack of 12 month RCTs. In fact, the only other program that had +12 month data was OPTIFAST which showed unclear long term weight loss.
#3: Very-low-calorie programs carry higher risks
In addition to the lack of long term RCTs on very low calorie programs like HMR, Medifast and OPTIFAST, the researchers noticed a higher risk of bias in the available studies and potentially higher health risks. They discuss a study in which risk for gallstones is 3x higher in a very low calorie diet vs a low calorie approach. The researchers say that clinicians should use these diets in very limited circumstances under close medical supervision.
#4: The food is varied, the social support is consistent
It is interesting to note that the researchers say that “although we conclude that Weight Watchers has weight-loss efficacy, whether it is superior to behavioral counseling is unclear.” Usually these studies were compared against an education or counseling control group. Counseling turned out to be a fairly high bar for many weight loss programs signaling the importance behavioral modification in making sustained change.
If you are getting health insurance make sure you take advantage of your preventative care benefits and choose a program that can help you make long term change.