Adipose tissue is a specialized connective tissue in the body that is the main store of energy in the form of triglyceride storage. Adipose tissue is generally found in mammals in two different forms such as white and brown adipose tissues. Depending on the species of mammal, the amount and location of the tissue varies. Most fatty tissues belong to the white category, which is found in various organs and in various parts of the body.

In humans, this tissue is found in multiple locations; it is found under the skin as subcutaneous fat, surrounding internal organs as visceral fat, within bones as bone marrow or yellow bone marrow, and also in the breast. The specific locations of these layers are called adipocyte depots. These deposits are a reservoir of adipose tissue that contains various types of cells; the largest percentage of cells are adipocytes that contain fat droplets. Some other cells, including fibroblasts, macrophages, and endothelial cells, are also part of this tissue along with several tiny blood vessels. As the integument system includes skin that accumulates at the deepest level of the subcutaneous layer, adipose tissue forms under the skin and provides insulation to the body from heat and cold.

It acts as a protective padding around all the vital organs of the body. Although its main function is to reserve lipids, it also acts as the main source of energy by synthesizing lipids to meet the needs of the individual. Obese people see themselves with more amount of adipose tissue in their body. Excessive tissues are seen hanging down from the abdomen and are also known as panniculus. Sometimes, to remove such fats, surgeries are needed. The abdomen has a layer of adipocytes known as visceral and intra-abdominal fat. Internal fat protects the stomach, liver, intestines, and kidneys by forming protective layers inside the body. Breast fat is also a type of white adipose tissue that helps in the formation of milk during pregnancy with the help of the hormone oxytocin and helps the mother to nourish the babies. In humans, excess fat accumulates in the abdomen, hips, and also in the thoracic regions.

Adipocytes are also found in different mammals; in mice they are found within the abdominal layers and cavity forming various deposits within the body. Even around the uterus and ovaries, it forms a layer of fat-filled mass that provides protection. Brown adipose tissues are densely packed mitochondria and are also found in various locations in mammals. As such tissues are good for vascularization, in hibernating animals they help regulate body temperature through non-shivering thermogenesis.