According to About.com, lipids are a diverse group of fat-soluble biological molecules that can be found throughout the body. They exist in the form of triglycerides, steroids, phospholipids, glycolipids, lipoproteins and waxes, Med-Health.net explains.
Elmhurst College states that a 154-pound male body contains roughly 24 pounds of lipids. The majority are triglycerides stored as adipose tissue. With proper hydration, the energy reserve from adipose tissue can maintain body functions for 30 to 40 days without food. Elmhurst College further explains that the fat depot also serves as insulation for the body and as a protection for sensitive organs, including the heart, liver, kidneys and spleen.
According to Med-Health.net, steroids regulate the structure while phospholipids provide the main building blocks of cell membranes. Glycolipids, found on the exterior surface of the membranes, play a vital role in the immune system. Since lipids are not soluble in water, in the bloodstream they are found in the form of lipoproteins.