By Levi Clancy for Student Reader on
Lipids are broadly defined as any fat-soluble (lipophilic), naturally-occurring molecules.
The term is also used more specifically to refer to fatty acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids), as well as other fat-soluble sterol-containing metabolites such as cholesterol. Lipids have many functions in living organisms including nutrients, energy storage, structural components of cell membranes, and important signaling molecules.
Although the term lipid is sometimes used as a synonym for fat, fats are in fact a subgroup of lipids called triglycerides and should not be confused with the term fatty acid.