Lipids are another type of natural polymer. Lipids are made of fat. They are used to make steroids and waxes. Waxes can be used as structure, just think of a beehive, it's made of wax. Lipids also give you energy. Then some of the steroids in your body contain hormones. Lipids also make a outer coating for all of your cells. Lipids make fat which helps keep you warm and all your internal organs. Lipids are also in butter, oils, and lard.