Calories: Fuel for your body

Calories are the energy in food. Your body has a constant demand for energy and uses the calories from food to keep working. Energy from calories fuels your every action, from fidgeting to marathon running.

Carbohydrates, fats and proteins are the types of nutrients that have calories and are the main energy sources for your body. No matter where they come from, the calories you eat are either converted to physical energy or stored within your body as fat.

These stored calories will stay in your body as fat unless you use them up. You can do this by cutting how many calories you take in so that your body must draw on reserves for energy. Or you can add more physical activity so that you burn more calories.