Understanding Obesity

September 26th, 2009 by LHill Leave a reply »

While body weight is made up of several components – bone, muscle, etc. when we talk about obesity we are referring to excess fat tissue, also called adipose tissue. There are two kinds of fat tissue, brown and white (like rice come to think of it). Brown tissue is mainly found in newborn babies which serves to protect babies by releasing heat. It is converted into white cells in adults. (Scientists are looking at whether white can be converted back into brown tissue and burnt off.) White adipose tissue is made up of cells called adipocytes. These contain fat made of triglycerides and other compounds. White fat cells secrete resistin, adiponectin and leptin. The average adult has 30 billion fat cells weighting about 30 pounds. Fat cells can increase in size about 4 fold before dividing and increasing the total number of fat cells present. Adipocytes also secrete estrogen which probably accounts for higher rates of some cancers in obese persons. Adipose tissue also secrete cytokines. Among the most interesting cytokines identified has been leptin, a molecule considered to send signals to the brain of satiety, i.e. the signal to the brain to stop eating.