A new study says healthy workplace initiatives don't work – at least as they're currently designed.

Researchers at the University of Pennsylvania said that even paying obese employees money to shed pounds won't work, either.

"More than 80 percent of large employers use financial incentives for health promotion," said Penn researcher Dr. Mitesh Patel. "Many use health premium adjustments, but these incentives are often delayed and, even when they aren't, they are typically hidden in paychecks." In other words, human resources mangers pay attention: reducing healthcare premiums in exchange for losing weight doesn't appear to be effective.

Patel added that those small bonuses strung out per paycheck seem "less noticable. Our findings suggest employers should consider testing design alternatives" to the premium-based incentive model.

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The study looked at 197 obese employees enrolled in three types of workplace wellness programs, each valued at $550. After one year, there were no significant changes in average weight loss for any of the participants. The problem seems to be the fact that the incentives to lose weight are too spaced out, despite being comparatively generous programs.

"Though participants in our study didn't experience significant weight loss, that doesn't mean that all incentive programs are ineffective," explained researcher Dr. David Asch, "only that we need to move to more creative designs."

"There is often a presumption that the size of the reward is all that matters," concluded Dr. Kevin Volpp. He's director of the Penn Center for Health Incentives and Behavioral Economics.

"In reality, incentive systems vary in effectiveness according to how well they are designed."