FAT PHYSIOLOGY: THE FAT CELL
Summary of main points.
• Fat cells are similar to other cells, but contain a lipid or fat pool for storage of fats to be used as energy.
• The average human body has 30-50 billion fat cells, and obese people have up to 100 billion.
• Most increases in fat mass are associated with increases in fat cell size.
• Lipogenesis refers to the storage of fat in fat cells; lipolysis the breakdown of fat.
• Lipogenesis and lipolysis are controlled by a number of enzymes and hormones.
• There is a constant cycle of fat storage and breakdown at the fat cell level, but increases in lipolysis do not translate into increases in fat burning.
• The state of energy balance j| the major influence in the lipogenesis/lipolysis cycle.
A fat cell (adipocyte) is similar in form to many other types of body cells with the exception of its storage ‘depot’—a lipid (fat) pool, which can make up to 90 per cent of the cell. Otherwise, the adipocyte has a cell nucleus, with all the ‘head office’ functions and genetic materials of other cells, and the cytoplasm (the ‘jelly’) and mitochondria (the ‘powerhouse’) characteristic of skin, bone and other organ cells.
The average fat cell stores around 0.5 micrograms of fat in its lipid pool (a microgram is a millionth of a gram) and the average, non obese individual has between 30-50 billion of these fat cells throughout his/her body (in fact more on her than him, as you’ll see below). Doing the sums on this, you can see that the average person will be carrying around 15kg of fat as his/her ’spare tank’, or energy reserve.
*23\186\4*
