A calorie is a unit of energy derived from food. Our body uses this fuel so it can do everything from breathing to secreting hormones to running a mile.
On average, your body needs 1,000 to 1,400 calories a day to keep your organs functioning, respiration going smoothly, and your brain focused.
If you take in more calories than you expend, the excess is stored as fat. If you eat fewer calories than that, you’ll lose weight.