The shows used a reality format to follow six people as they tried to eat less and exercise more. Those who were on camera lost an average of 8.1 percent of body weight.
Deneen Vojta, a physician and senior vice president of the UnitedHealth Center for Health Reform and Modernization, said even a small weight loss can reduce diabetes risk.
"At 3.3 percent, we were thrilled," she said.
Getting people to lose weight is notoriously difficult. She was heartened that "the more people watched and participated, the more they lost. It was linear."
Research results from the study were published Thursday in the journal Obesity. The program was designed in collaboration with Ronald T. Ackermann, a Northwestern University diabetes-prevention expert.
Of the 306 people in the study, 204 were from Philadelphia.
Thomas Wadden, an obesity expert at the University of Pennsylvania, said he thought the results were promising.
Doctors often tell people not to watch TV, he said, because being a couch potato puts the pounds on. "This is a show that you could get behind," he said.
He said the program likely needed to build in more accountability for participants. A control group would also have been a good idea.
Using recordings that can reach large numbers of people is the wave of the future in a country where obesity is at epidemic levels. "I do think this is where weight loss is moving," he said. "It's moving toward remotely delivered interventions."
The UnitedHealth approach was based on the Diabetes Prevention Program (DPP), a pivotal study published in 2002 that proved small improvements in weight and exercise could reduce the risk of diabetes. That program, which required more extensive face-to-face intervention, led to an average weight loss of 7.5 percent at six months, Wadden said.
A 5 percent loss is usually thought of as the cutoff for "clinically significant improvement in your cardiovascular disease risk factors," he said. Smaller losses are still good.
"A little bit of weight loss is good for your health," he said. "A bigger weight loss is better for your health."
Vojta said every 2.2 pounds of weight loss leads to a 16 percent decrease in diabetes risk.
She said recruitment for the study was so easy that UnitedHealth had to turn people away.
That said, the show didn't captivate everyone. Of those who signed up, 13 percent did not watch any episodes and 23 percent watched only one to four. Only 36 percent watched nine or more.
Vojta said study organizers quickly realized they needed to create stronger programming. "We really didn't have cliff-hangers, like they do in real reality shows," she said. Going forward, the program will use more incentives and gaming techniques. Episodes will be shorter. There will be more information about sleep, which is considered more important for weight loss now than it was when the original DPP was conducted.
UnitedHealth has no plans at the moment for further work with Comcast, although the shows, called Not Me, are still available on demand in Philadelphia. The insurer has already begun offering the program to big clients, such as General Electric, that pay extra for the program, as though it were a claim.
Wadden said the video-based approach, which is less expensive than standard weight-loss programs, makes sense as a first step for motivated employees. Others may still need one-on-one appointments with nutritionists and other diet experts.