Do Apps That Pay You to Lose Weight Really Work?

They say there's no such thing as a free lunch. But what about a healthy lunch you get paid to eat? That's more or less the premise of weight-loss apps like DietBet and HealthyWage. Users place bets on losing X pounds in Y months, and those who achieve their goal win money or at least, don't lose money.

There are also similar apps to encourage people to exercise. RunBet pays you to run. Sweatcoin pays your for steps. Achievement pays you not just to exercise but to meditate, track your sleep and tweet about your health.

Do the financial incentives these apps offer actually motivate people? Research says yes — as long as you keep using them. An August 2019 study published in ‌JAMA‌ found that Achievement users increased their physical activity if they got paid regularly for it.

Researchers rewarded participants for the number of steps they took, with amounts from $0.10 to $3.50 per 10,000 steps. People responded especially well to consistent payments (as opposed to increasing or decreasing the amount). Unfortunately, after the experiment ended, everyone returned to their pre-study behavior.

The relapse was no fluke. Contestants on ‌The Biggest Loser‌, a reality TV competition that awarded $250,000 to the person who lost the highest percentage of their weight, encountered a similar outcome. Six years after being on the show, all but one participant regained significant weight or got heavier than they were before the show, according to an August 2017 study published in ‌Obesity‌.

A 2014 review in the ‌Journal of the Academy of Nutrition and Dietetics‌ took a broader look at incentive models for losing weight, including a lottery setup resembling various betting apps. Whatever the model, the result was essentially the same. "Financial incentives were found to have a positive short-term effect on dietary behavior," the review's authors wrote, but "behavior change did not appear to be maintained."

‌Read more:‌ 9 Things You DON'T Have to Do to Lose Weight

Fortunately, incentive apps don't have an end date. As long as you keep using them, you can keep benefiting. The trick is to find something you ‌want‌ to use. "Pick an app that sparks your interest," says Erin Morse, RD, chief clinical dietician at UCLA Health. "If you don't love it, you won't use it."

Yoni Freedhoff, MD, medical director of the Bariatric Medical Institute, agrees that enjoyment is vital. "What matters most in terms of efficacy long-term is liking the life you're living while you're losing the weight," he says. "If you don't — even if you're getting paid — you're not likely to stick with [it]."

Alternatively, you can find something you dislike to reverse-motivate you. "Losses tend to be about twice as motivating as the same gains," says Katherine Milkman, a behavioral economist at the University of Pennsylvania and coauthor of the JAMA study. "You can either give me $10 or take away $5 and get the same motivational result."

One app leveraging this is stickK. Users set a goal (like losing 20 pounds) and bet money on achieving it. If they fail, the money goes to an organization they particularly dislike.

Another strategy is finding an app with a check-in or reminder feature. Dr. Freedhoff says anything that cues you to maintain a behavior change is useful. That might mean a push notification, calendar reminder or a simple sticky note on the fridge.

And DietBet structures some of its programs around check-ins. Its Transformer game, in which people bet on losing 10-percent of their weight over six months, has participants submit their weight each month. If they stay on track, they can win money every time.

‌Read more:‌ How to Lose Weight Fast — the Healthy Way

Ideally, though, people would internalize their healthy changes and no longer need prodding. Despite the studies in which participants returned to their old ways after the incentive period ended, there's also evidence that financial rewards can help new behaviors stick under the right conditions.

"We can create habits with incentives if they last long enough," Milkman says, pointing to a 2009 study on gym attendance in ‌Econometrica‌. Non-regular gym attendees were paid to go to the gym, some for one week and others for eight weeks.

The researchers, who continued tracking participants for seven weeks after payments stopped, discovered that those in the eight-week group kept going to the gym at a significantly higher rate than those in the one-week group, even though they were no longer getting paid for it.

Encouraging as these findings are, Dr. Freedhoff urges people to recognize that "there are no rules that apply to everybody." Similarly, Morse notes that financial incentives don't address mental or emotional health and may leave some people cold. "See what motivates you as an individual and find the tools you need to achieve your personal nutrition, fitness, weight and wellness goals," she says.