Long-Term, Two-Year Data Shows That One Year on Weight Watchers Results in More Weight Loss, Greater Health Benefits and is Cost Effective

NEW YORK (May 3, 2017) – Weight Watchers International, Inc. (NYSE: WTW) announced results from a two-year study published today in The Lancet which found that adults with obesity referred to Weight Watchers for one year lost significantly more weight and were able to keep it off for longer compared to those who either received brief advice and self-help materials, or were referred to a 12-week Weight Watchers program. Those on both the 12- and 52-week Weight Watchers program also had greater blood sugar control and greater reductions in body fat than those on the brief intervention program. 

Lead author Dr. Amy Ahern of the MRC Epidemiology Unit at the University of Cambridge stated, “We’ve seen before that a 12-week program can help people lose weight, but for the first time we’ve shown that extending this to a full year leads to greater weight loss over a longer period and a lower risk of diabetes. Although the initial costs of the year-long program are greater, it’s very likely that it will be good value for money over the long term because of the reduction in weight-related illnesses.”

The randomized, prospective, controlled clinical trial looked at weight loss among 1,267 participants randomized to attend Weight Watchers for a 12- or 52-week period, or to receive brief advice, alongside self-help materials and regular weigh-ins. The large independent study was conducted by research teams led by Dr. Amy Ahern at the University of Cambridge; Professor Jason Halford and Dr. Emma Boyland at the University of Liverpool; and Professor Susan Jebb and Professor Paul Aveyard at the University of Oxford.

This trial was funded by a National Prevention Research Initiative grant and the cost of the Weight Watchers program and blood sampling and analysis were funded by Weight Watchers as part of an MRC Industrial Collaboration Award. 

At one year, participants assigned to 52 weeks of Weight Watchers lost, on average, more than twice as much weight as those in the brief intervention group. They were also more likely to lose 5% and 10% or more of their initial weight as compared to the brief intervention and 12-week Weight Watchers groups, which are weight loss milestones that are associated with significant health benefits. Additionally, compared to participants in the other groups, those in the year-long Weight Watchers program also had significantly greater reductions in fasting blood glucose and glycosylated haemoglobin, which are important markers of the future risk for developing type 2 diabetes.

Study participants attended a final measurement appointment at 24 months, a full year after treatment had ended. Although there was weight regain among all groups, the group assigned to 52 weeks of Weight Watchers, as compared to the other two groups in the study, experienced superior weight losses and improvements in waist and fat mass that were sustained even two years down the line.

The researchers also modelled the impact of the three programs over the next 25 years to predict cost effectiveness, among other factors. They found that the incremental cost effectiveness ratio for the 52-week program was cost effective compared to the brief intervention and the 12-week program.

“These data replicate earlier and smaller studies proving that Weight Watchers provides clinically meaningful weight loss in a cost effective manner. This study of over 1,200 people is notable in that, as compared to the brief intervention or 12-week Weight Watchers groups, the superiority of the one year Weight Watchers program was still evident after two years,” said Gary Foster, PhD, Chief Scientific Officer, Weight Watchers International, Inc. “These two-year data indicate that our liveable, scalable program can provide long-term sustainability.”

According to the CDC, as of 2014, more than one-third of U.S. adults have obesity. Additionally, the estimated annual medical cost of obesity in the U.S. was $147 billion in 2008 U.S. dollars; the medical costs for people who have obesity were $1,429 higher than those of normal weight[1].

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About Weight Watchers International, Inc.

Weight Watchers International, Inc. is one of the most recognized and trusted brand names among weight-conscious consumers. Weight Watchers provides commercial weight management services through a global network of Company-owned and franchise operations and offers innovative, digital weight management products through its websites, mobile sites and apps. These services and products are built on the Company’s weight management program, which helps millions of people around the world lose weight through sensible and sustainable food plans, activity, behavior modification and group support. Weight Watchers has an unparalleled network of service providers to assist members on their journey and also offers a wide range of products, publications and programs for those interested in weight loss and healthier living.


This trial was funded by the UK National Prevention Research Initiative (a collaboration of government departments, research councils and major medical charities). The cost of the Weight Watchers program and blood sampling and analysis were funded by Weight Watchers as part of an MRC Industrial Collaboration Award. 

Conflicts of Interest

ALA, SAJ, EJB, BRM and JCGH have received research funding to their institutions from Weight Watchers International and have given and received hospitality from providers of commercial weight loss services on a small number of occasions. PA and SAJ have conducted another publicly funded trial in which part of the intervention was delivered by and donated free by Slimming World and Rosemary Conley, and they are principal investigators on a trial funded through a grant to the University of Oxford from Cambridge Weight Plan. JCGH is Principal Investigator on studies funded through research grants to the University of Liverpool from the California Prune Board, Ingredion and American Beverage Association (ABA), and has studentships funded through BBSRC and ESRC with Unilever, Coca-Cola, and Tate & Lyle. JCGH provides expertise on health, weight management and appetite control to the food and beverage, commercial weight management, pharmaceutical and ingredient sectors.

[1] Adult Obesity Facts. CDC. Last accessed: May 1, 2017