A better way to think about it: "You'll see more impressive results by focusing on changes that are part of a regular routine," says registered dietician Keri Glassman, the author of The New You (and Improved!) Diet. "Consistency is key." For example, if you drink an 8-ounce glass of soda every afternoon, switching to sparkling water could save 700 calories a week. But if you only drink soda at the movies, say, once a month, try to find a smarter substitution (the bagels you pick up on your way into the office, perhaps) with a bigger payoff.