What Are Lipids?

Fats and cholesterol belong to a special group of molecules called lipids. The members of this club have something pretty significant in common: they are relatively insoluble in water. This might not seem like a big deal, but keep in mind that most of our planet’s surface is water and, more important to our topic, most of our body is water as well. Because of their inability to dissolve into water, we must make special concessions to accommodate lipids both during digestion and also inside of the body.

Fat and cholesterol are lipids, which are a group of molecules that don’t dissolve well into water.

During digestion, an emulsifying substance called bile is called to action to facilitate lipid digestion and absorption. As for fat and cholesterol inside of the body, they require special transport shuttles to circulate. Fat also has its own cell type specifically designed for storage. These cells are called adipocytes, or more commonly “fat cells,” and large collections of adipocytes are called adipose tissue. Adipose tissue is found under the skin (subcutaneous fat) and in deeper deposits (visceral fat) such as in the abdomen, around vital organs, and throughout skeletal muscle.