Most likely, though, you've just hit a plateau, which is a fancy way of saying your body has adjusted to your lower calorie intake. To bust out of it, you need to change your workout by exercising longer or more intensely. "Cutting calories could also work, but it's not advisable to consume fewer than 1,500 calories a day because it's extremely difficult to fulfill all your nutrient needs," Sass says.
Sure, there's your one friend who swears by the Taco Cleanse. And that other friend who ate nothing but broccoli soup for a month and dropped 20 pounds, found the love of her life, and got promoted at work. But before you start blending 80 stalks of broccoli into a cup or crunching your way through a crate of tacos, check out which diets are backed by science. Because don't you want to try one that will do the trick for you?