From Jennifer R. Scott,
Your Guide to Weight Loss.
FREE Newsletter. Sign Up Now!

About.com Health's Disease and Condition content is reviewed by our Medical Review Board

The first step to losing weight by counting calories is to understand what a calorie is and how it applies to your weight. A calorie is a unit of measurement that measures the amount of energy contained in a food or beverage.

Your body uses caloric energy to perform everything from basic biological functions to typing on your keyboard or jogging around the block. We all have a certain caloric requirement needed to maintain our current weight; if you eat fewer -- or burn more -- calories than that, you will eventually lose weight. This is called a caloric deficit. A good rule of thumb is that a caloric deficit of 3,500 calories leads to a weight loss of approximately one pound.