Need a new incentive to help you stick with your diet? You may want to join one of those weight loss websites where you bet money on your success. According to the Annals of Internal Medicine, individuals who put just $20 bucks on the line every month lost four times as much weight as those who didn’t have money at risk. And those who were vying for a “winner take all” pot lost even more weight.

Researchers put obese volunteers on 5-man teams. If all 5 met their monthly weight-loss goals, each person got $100 bucks. But if only one of the team members lost weight, they got the whole $500 dollar pot. So, why was this so effective? The researchers say that we tend to overestimate our own abilities, and underestimate other people’s, and having a shot at the whole bonus pool made the reward seem much bigger.

So, how can this translate into the real world? Harvard University public health expert Dr. Jason Riis says a lot of employers are considering offering cash incentives to help employees lose weight, because overweight workers cost more to insure. So, talk to a company rep about setting up incentives.

Until then, he suggests creating your own office weight-loss pool. If you can’t find enough takers, there are goal-setting websites where you can put your money where your mouth is, and you can double your investment if you succeed, like Healthy Wage, and Stickk.com.