The digestive system transforms food into energy through a multi-step process. It begins with the mouth which breaks down food, then the esophagus transports food to the stomach where it is further broken down with enzymes. Nutrients from food are then absorbed in the small intestine and waste is passed through the large intestine and anus. Key organs like the liver and stomach aid in digestion by filtering waste, storing nutrients, and breaking down food into a smaller form.