This document summarizes key information about lipids and fats: 1. Lipids are organic compounds that are greasy to touch and insoluble in water but soluble in organic solvents. They contain carbon, hydrogen, oxygen, nitrogen and phosphorus and are a concentrated source of energy. 2. Fats are composed of triglycerides, which are esters of glycerol and fatty acids. Fatty acids are the building blocks of several lipid classes. Unsaturated fatty acids contain one or more double bonds and are important for growth and health. 3. Lipids serve many functions in the body including as an energy source, insulating and protecting tissues, carrying fat-soluble vitamins, and