Adipose tissue is a loose connective tissue composed mainly of lipid-rich cells called adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as macrophages. There are 2 types of adipose tissue: white adipose tissue (mainly in adults) and grey adipose tissue (mainly in newborns). Adipose tissue is mainly located under the skin but can also be found as deposits in the muscles and intestines.

The fat cell system stores energy, acts as an endocrine organ, insulates and protects the body. Abnormal proliferation and regulation of cells within the adipose system contribute to the development of disorders such as obesity and cardiovascular disease.