Physiology

Adipose tissue is a type of connective tissue that synthesize and store fat, releasing it for metabolism in fasting. Two types are present: white adipose tissue which has a structural, cushioning function and found in a wide variety of locations in the mammalian body. And the metabolically more active brown adipose tissue, which is involved in heat production to maintain body temperature and mainly found in subscapular, interscapular, and mediastinal areas. Much of the body fat reserve is subcutaneous; in addition there is adipose tissue around the organs, which serves to protect them from physical damage. 

In lean people, 15-25% of body weight is adipose tissue, increasing with age; the proportion is greater in people who are overweight or obese. Adipose tissue contains 82-88% fat, 2-2.6% protein, and 10-14% water. The energy yield of adipose tissue is 8000-9000 kcal (34-38 MJ) per kg or 3600-4000 kcal (15.1-16.8 MJ) per pound.Free fatty acid is "liberated" from lipoproteins by lipoprotein lipase (LPL) and enters the adipocyte, where it is reassembled into triglycerides by esterising it onto glycerol. In humans, lipolysis is controlled though the balanced control of lipolytic B-adrenergic receptors and a2A-andronergic receptor mediated antilipolysis.