Minding your food portions is crucial to losing weight. But relying on small, pre-portioned packages to do the work for you may backfire, says a new study in the Journal of Marketing. People actually ate multiple packages and up to twice as many gumdrops when they were wrapped in small packages versus loose in a bowl. "People thought they didn’t have to worry about watching calories or how much they ate because the package would help them, but once they made that decision, they basically couldn’t stop eating," says Jennifer Argo, Ph.D., Cormie professor of marketing at the University of Alberta in Canada. To help fight the urge, stick to one single-packaged treat at a time or portion a serving out from a larger package (eating straight from the bag can also cause you to eat more food) before sitting down to eat.