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1. Make Your Sandwiches Greek

We've all heard of swapping mayo for mustard, a lower-calorie choice. But what if you don't like the yellow stuff? Go Greek—yogurt, that is. Per tablespoon, nonfat Greek yogurt contains a healthy dose of protein and good-for-the-gut probiotics, plus about 80 fewer calories than mayo, says Keri Gans, a registered dietician and the author of The Small Change Diet says. Plus...that tangy taste.