"We demonstrated that an incentive program that provides frequent positive feedback can be very effective at changing behavior," said lead study investigator Dr. Kevin Volpp, director of the Leonard Davis Institute of Health Economics Center for Health Incentives at the University of Pennsylvania in Philadelphia.
Although the study demonstrates the success of such incentive-based weight loss programs, the participants were not followed long enough to show whether such programs have long-term success.
"A key challenge in weight loss interventions is to both attain initial weight loss and to maintain that weight loss over periods of 12 months or more," the researchers said. "Further testing of longer term use of these incentives is needed to determine whether longer use would lead to sustained weight loss."
Still, many diet experts say that they encourage the use of incentives for weight loss to their patients.
"I use this philosophy when patients tell me that there is no way that they can possibly lose a lot of weight -- and I make the point to them that it all depends on what the incentive is," said Dr. Carl Lavie, medical director of cardiac rehabilitation and prevention at Ochsner University's Heart and Vascular Institute in New Orleans. "Let's say a man is 250 pounds and his ideal weight is 180, and he does not think that he can even lose 10 pounds, much less 30 or 40. I make the point of asking him if someone offered you $10 million if you lost 40 pounds in so many months, do you think you could do it -- they all say 'absolutely.'"
But many diet experts remain wary of the long-term success of such incentive-based approaches to weight loss.
"The problem with the reward approach is once the money was not available, the incentive is lost and weight is quickly regained," said Dr. Jana Klauer, a private practice physician specialist in nutrition and metabolism and author of "How the Rich Get Thin."
"The idea is really no different from that of losing weight for a special occasion and then regaining after the event has passed."
And although the most recent study on incentive-based weight loss programs bolstered the success of using financial rewards for meeting weight loss goals, it also showed that the effectiveness of this technique began to wane in time.
"While this intervention worked, the benefit was fast disappearing at the seven-month mark," said Dr. David Katz, director of medical studies in public health at the Yale University School of Medicine in New Haven, Conn. "That is about the same success seen with almost any fad diet."
So while experts believe that an incentive-based weight loss program is often successful in helping someone to jump-start weight loss, most agreed that the weight loss achieved through such a program cannot be sustained without finding a deeper motivation for weight loss that goes beyond the financial reward at the end of one program.
"If we are going to achieve lasting change in health behavior, we need to help people to internalize the sense of responsibility to self and self-care and to value their own well-being," said Martin Binks, director of behavioral health and research director at the Duke Diet and Fitness Center. "This speaks to the necessity of treating the whole person."
In Velarde's case, finding the larger goal beyond simply winning the lottery at the end of her weight loss challenge is what allowed her to keep the weight off for the last year and a half.