Nutrition In order for the human body to be healthy and resistant to disease, good nutrition is required. All living things are made of chemicals. In order to grow, develop and maintain bodily structures and functions, specific chemicals must be acquired from the food we eat. In a sense, we are what we eat. Nutrients can be divided into the following categories: Nutrients Overview Carbohydrates ? sugar based molecules that are metabolized for energy in cellular respiration and make up the structural components of plant cell walls. Lipids ? fat based molecules that store large quantities of energy. These molecules also make up the structure of cell membranes.