April 6th, 2015
Weight-Loss Programs: Slim Evidence and Thin Results
A new study concludes that some weight-loss programs may be slightly better than other programs but that in the long run none of the programs have been able to show a substantial weight loss over a sustained period. For even the best programs, an editorialist writes, “weight loss is modest and likely below patients’ expectations.”
In a paper published in Annals of Internal Medicine, researchers report on an updated systematic review of studies evaluating weight-loss programs. They looked for U.S. trials involving 31 different programs but were able to find only 45 studies that qualified (and only 39 of these were randomized, controlled trials) involving only 11 of the weight-loss programs. (The 11 programs were Weight Watchers, Jenny Craig, Nutrisystem, Health Management Resources, Medifast, OPTIFAST, Atkins, The Biggest Loser Club, eDiets, Lose It!, and SlimFast.)
The trials that were performed were plagued by numerous shortcomings, including limited duration and followup, high rates of dropouts in people participating in the trials, poor adherence to the diet programs, and a high risk of bias.
As the one-eyed man is king in the land of the blind, only two weight-loss programs, Jenny Craig and Weight Watchers, were able to show even a modest weight loss at one year. Compared to controls, who generally received traditional counseling and education, weight loss was only 2.6% greater for Weight Watchers and 4.9% greater for Jenny Craig. At three months Nutrisystem led to a 3.8% greater weight loss. Very low-calorie programs like Health Management Resources, Medifast, and OPTIFAST resulted in a 4.0% greater short-term weight loss but these losses were attenuated over time. The evidence to evaluate most self-directed programs was weak. Low-carb programs like Atkins had promise but the trials were limited by design problems and bias.
In an accompanying editorial, Christina Wee writes that the study “highlights something that researchers in the behavioral weight-management field have known for decades: Structure and intensity of contact are highly correlated with program success. It is unsurprising that highly structured programs with in-person social support, such as Weight Watchers and Jenny Craig, seem more effective in the long term than less structured interventions.”
The study authors concluded with a very modest endorsement of Weight Watchers and Jenny Craig, stating that “clinicians might consider prioritizing referral only for those commercial programs that have a substantial body of evidence showing a consistent, long-term effect.”
But, writes Wee, the weight loss with such programs, including Weight Watchers and Jenny Craig, “is modest and likely below patients’ expectations.” She concludes: “Whether patients value the modest weight loss produced by these programs enough to absorb the financial cost and sustain behavioral change is also unclear.”