What is a calorie?
A calorie is a unit of measurement, like ounces or inches. Just as ounces measure weight, and inches measure height, calories measure energy - both the energy you get from food, and the energy you use with activity.
Calories are good for you
You need calories to stay alive. Everything you do – from sleeping to climbing trees – requires calories. A 20 minute walk, for example, burns about 90 calories (depending on your height, weight, and age).
Exercise burns more calories than sleeping of course, but it is important to remember that your body is constantly burning calories, regardless of what you are doing.
Most people burn between 1200 and 2000 calories each day simply by breathing, thinking and doing all the other things that require energy. Any significant exercise – whether it’s walking or vacuuming – burns additional calories on top of this basic 1200 to 2000.
But too many calories are bad for you
Your body gets the calories it needs from food. The number of calories depends on the type of food or drink, and how big the serving is. A medium-sized apple, for example, has 95 calories. A big apple has 116 calories. A piece of apple pie with cream on top has about 330 calories.
Eating is good - it gives you the calories you need to live. BUT the problem is, if you eat more calories than your body needs, these extra calories are stored by your body. Over time, storing calories in this way makes you gain weight.
If, on the other hand, you burn more calories than you eat, you will slowly lose weight.