How does food turn into energy?

Food turns into usable energy when your body breaks it into small fuel molecules, then your cells use oxygen to release energy from those molecules. Much of that energy is packed into ATP, a tiny molecule your muscles, brain, and heart can spend.

The busiest helpers are mitochondria, small parts inside cells that process glucose and help make ATP. A single sugar molecule can lead to many ATP molecules, and your body makes them constantly, even while you sit still and think.