I cut my daily calorie intake drastically but haven't lost weight. Why?

Simple: Your body is used to a certain amount of food, and when that amount falls drastically it doesn’t think, “Ah, it must be swimsuit season.” Instead, it assumes there’s a famine going on. And because your body cares more about keeping you alive than slimming your thighs, your metabolism (the rate at which you burn calories) slows down. “Imagine your metabolism is a fire, and food is what feeds that fire,” says personal trainer and registered dietitian Gina Crome of Lifestyle Management Solutions. “Without food, the fire dies down and so does your metabolism.” To optimize weight loss, Crome recommends you keep that metabolic fire at a comfortable burn by eating small healthy meals and snacks throughout the day. 

The other culprit: Guessing. Unless you are weighing out all of your food portions and keeping a food diary of every calorie (including that milk in your coffee), there’s a good chance you’re actually consuming more than you realize. “People have a better sense of what they’re actually consuming when they write it down,” says Laura M. Rosch, D.O., who specializes in obesity and nutritional disorders at the Garrett Wellness Center in Chicago.