## Fighting out Fat and Calories

### What Are Fat and Calories?

Fats, or lipids, are nutrients in food that the body uses to build cell membranes, nerve tissue (like the brain), and hormones. The body also uses fat as fuel. If fats that a person has eaten aren't burned as energy or used as building blocks, they are stored by the body in fat cells. This is the body's way of thinking ahead: By saving fat for future use, it plans for times when food might be scarce.

A calorie is a unit of energy that measures how much energy food provides to the body. The body needs calories to function properly.

### Food Labels: Calories

Food labels list calories by the amount in each serving size. Serving sizes differ from one food to the next, so to figure out how many calories you're eating, you'll need to do three things:

1. Look at the serving size.
2. See how many calories there are in one serving.
3. Multiply the number of calories by the number of servings you're going to eat.

For example, a bag of cookies may list three cookies as a serving size. But if you eat six cookies, you are really eating two servings, not one. To figure out how many calories those two servings contain, you must double the calories in one serving.

When you start looking at food labels, you may be surprised at some of the serving sizes. For example, on the labels of six cold breakfast cereals, the serving size ranges from ½ cup to 1¾ cups. You would have to more than triple the smallest serving size to compare the calories in that cereal with the calories in the cereal with the largest serving size (1¾ cups). A small bag of corn chips may contain two or more servings — although most people would eat the entire bag! That's why it's always important to check the serving size of all foods on the label.