The document discusses how much exercise is needed to burn the calories from common foods like chocolate cake, pizza, and a cheeseburger and fries. It states that 45 minutes of walking or cycling is needed to burn the calories from one piece of cake, 60 minutes of jogging is required for two pieces of pizza, and over 90 minutes of running to burn the calories from a cheeseburger and fries. The document encourages readers to consider if expending this much time and effort through exercise is worthwhile for consuming these foods.