Science Center

What Research Says About WeightWatchers

Leading researchers have studied the WeightWatchers program for more than four decades. Here’s what they have to say.
Published February 1, 2021

Since its foundation in 1963, WeightWatchers has always been rooted in science. Our dedicated Science team uses credible, cutting-edge research to inform our consistently-evolving program, and works closely with the academic scientific community to ensure we meet the highest standards. WeightWatchers is committed to research that addresses knowledge gaps in the field of weight management.

Over the past four decades, over 140 studies have been published on WeightWatchers, including more than 35 publications using gold standard randomized controlled trials examining the efficacy and impact of the WeightWatchers program. The body of evidence is clear: WeightWatchers is an effective, scalable, and cost-effective program with sustained weight loss and wellness outcomes.

The research doesn’t stop here though: we’re committed to continuing to work with the scientific community to advance the scientific literature and stay up to date on the latest in weight management-related science.

Significant & Effective Weight Loss

WeightWatchers has been evaluated across the world and was found to produce significant weight loss, defined as at least 5% of body weight, across the globe including the United States, United Kingdom, Germany, China, and Australia.

In numerous randomized, controlled studies, WeightWatchers was found to be more effective for sustained weight loss—defined as 6 to 12 months—compared to:

  • Do-it-yourself approaches: WeightWatchers is greater than 2 times more effective for weight loss than DIY.1
  • Physician counseling: WeightWatchers is 2 times more effective for weight loss than physician counseling.2
See below a selection of studies highlighting the efficacy of WeightWatchers:

Weight-Loss Maintenance

WeightWatchers is effective as a long-term weight management strategy, producing clinically significant weight loss at two years, which is the gold standard for long-term data in the field.

In addition to our randomized controlled trial data showing maintenance of weight loss at 2-years, see below a selection of studies evaluating the behaviors of WeightWatchers weight loss maintainers who make up the WeightWatchers Global Success Registry, a growing group of 13,000+ WW members. We are consistently doing additional analyses in this group, who upon the last publication (n=6139) have lost an average of 50+ pounds and maintained it for 3.3 years.

See below a selection of studies evaluating the long-term efficacy of WeightWatchers:


WeightWatchers' diabetes-tailored plan is based on guidelines from the American Diabetes Association and the International Diabetes Federation. Both have been evaluated and found to be effective for:

Type 2 diabetes

  • WeightWatchers is 2 times as effective for weight loss than standard diabetes nutrition counseling and education, and produced greater improvements in glucose control in those with type 2 diabetes.5
  • Results from the six-month clinical trial evaluating the diabetes-tailored program showed clinically meaningful and statistically significant effects on weight loss, glycemic control, and reducing diabetes distress.6
  • WeightWatchers is 27 times more effective for weight loss than a self-initiated program and produced greater improvements in glucose control in those with prediabetes.7
  • WeightWatchers is recognized by the U.S. Centers for Disease Control and Prevention (CDC) as a diabetes prevention program.

See below a selection of studies evaluating the efficacy of the WeightWatchers program for members living with diabetes and prediabetes:

Weight Stigma

WeightWatchers is a fierce advocate against weight stigma, bias, and discrimination and has funded, conducted, and published 10+ papers to better understand the experiences rooted in weight bias for those living in larger bodies, including consequences of stigma, with the goal of helping those affected and ultimately supporting policy-based solutions.

See below a selection of studies to better understand weight bias, stigma and discrimination:

Cost Effective

In a review of weight-loss programs, WeightWatchers was shown to be the most cost-effective when compared to other clinically proven nonsurgical programs such as Vtrim, Qysmia, Orlistat, and Jenny Craig.

See below a selection of studies highlighting the cost-effectiveness of the WeightWatchers program:

Other notable research related to the WeightWatchers program:

For the full compendium of research evaluating the WeightWatchers program, please email