ELI5: What is a calorie?

A calorie is like a tiny unit of energy that your body uses to do everything.

Think of your body like a car. A car needs gasoline to drive. Your body needs calories to run, play, think, and even sleep! Calories come from the food and drinks you consume.

Imagine a little worker inside you. This worker takes the calories from your food and turns them into energy.

• If you eat more calories than your body uses, the extra calories get stored as fat for later. It's like putting extra gasoline in a storage tank in your car.
• If you eat fewer calories than your body needs, your body uses the stored fat for energy. It's like using the gasoline from the storage tank when you run out.

• An apple might have 80 calories.
• A candy bar might have 250 calories.