The secret to eating less and being happy about it may have been cracked years ago—by McDonald's. According to a new study from Cornell University's Food and Brand Lab, small non-food rewards—like the toys in McDonald's Happy Meals—stimulate the same reward centers in the brain as food does. The researchers, led by Martin Reimann, carried out a series of experiments to see if people would choose a smaller meal if it was paired with a non-food item. They found that the majority of both kids and adults opted for a half-sized portion when combined with a prize. Both options were priced the same. Even more interesting is that the promise of a future reward was enough to make adults choose the smaller portion. One of the prizes used was a lottery ticket( 彩票 ), with a $ 10, $ 50 or $ 100 payout, and this was as effective as a tangible gift in persuading people to eat less. " The fact that participants were willing to substitute part of a food item for the mere prospect of a relatively small monetary award is interesting," says Reimann. He theorizes that it is the emotional component of these intangible prizes that make them effective. In fact, vaguely-stated possibilities of winning a prize were more effective than options with hard odds included. " One explanation for this finding is that possible awards may be more emotionally provoking than certainty awards," says Reimann. " The uncertainty of winning provides added attraction and desirability through emotional ' thrills. ' The possibility of receiving an award also produces a state of hope—a state that is in itself psychologically rewarding. " In other words, there's a reason why people like to gamble. How might this knowledge be used to help people eat more healthily? One possibility is a healthy option that offers the chance to win a spa( 温泉疗养 )weekend. Or maybe the reward of a half-sized portion could be a half-sized dessert to be claimed only on a future date. That would get you back in the restaurant—and make you eat a little less.