Lipids are a group of organic molecules, most of which do not dissolve in water. The process at which, lipids move through the body so that they can be, digested and absorbed are as followed.

Most digestion begins in the small intestines; however, within the liver, the bile produced helps to emulsify fat to aid its digestion and absorption in the small intestine. Bile is a substance that aids in fat digestion and absorption, and is, secreted by the gallbladder, which aids this process by breaking large fat drops into small globules, which can then be broken-down by fat-digesting enzymes from the pancreas. The mixture of fatty acids, the partially digested triglycerides, and bile forms smaller droplets called micelles, which facilitate absorption. Once absorbed, the triglycerides are, reassembled and most of the bile acids are, returned to the liver to be, reused. In addition, lipids travel in the blood in lipoproteins. Lipids and bile form micelles, which aid lipid absorption. Lipoproteins help transport lipids through the blood.

Lipids are stored in the body during fasting in which, adipose tissues are broken down and the fatty acids and glycerol are, released into the blood. Some triglycerides are, used immediately for energy and others are stored for future use. Therefore, lipids are continuously stored and then broken down, depending on the immediate energy needs of the body in adipose tissues, which provides a concentrated source of energy.