What are fat cells for? This might seem an odd question, but many people haven’t a clue. The only thing we all know for sure – or think we do - is that nobody wants them.
The fat cell is an energy store – and an amazingly efficient one. If you take in more energy (i.e. eat more calories) than you need, your body stores the excess calories for use at a later date. Your body has two main mechanisms for storing energy. One is to store some of the calories as glycogen, a form of glucose, in the muscle and liver. When the glycogen stores are full, your body then begins to store calories in fat cells. Each pound of fat stores an impressive 3,500 calories. So if you are 50lbs overweight, you have around 175,000 calories (3,500 x 50) available to “spend”. This would provide enough energy for 20 whole days of non-stop walking.
Some fascinating scientific studies over the past two decades, however, show that the humble fat cell is more than just a warehouse for energy supplies. Fat cells are intimately involved in sophisticated signalling to the brain, muscle and other body tissues via a family of chemical/hormonal messengers. These various pathways represent a complex regulatory system, controlling body fat stores and appetite.
Even if you don’t find any of this especially interesting, it’s important from a practical standpoint. I do say to my patients that if they don’t feel hungry, they don’t need to eat. This remark is often met with a look of surprise or even incredulity. One patient said to me recently, “But if I don’t eat, where am I going to get all the energy I need to survive?”
I pointed out that on a conservative estimate he had around 250,000 stored calories available for whatever energy-demanding tasks he had in mind; so missing the occasional meal would not cause lasting damage. I’m not advocating this as a method of dieting at all – absolutely not - but merely to illustrate that people seem not to see fat as an energy store to be used up – but that’s exactly what it is.
Dr David Ashton MD PhD
9th May 2012