In this extract from Fat: The Secret Organ, obesity researchers Mariette Boon and Liesbeth van Rossum explain the purpose of fat in the body and how long it can keep us going without food.
When we talk about the fuel ‘fat’, which is suspended in our blood and which can be absorbed and burned by organs, what we’re referring to are fatty acids. These are long ‘tails’, or chains, that are usually made up of 16 to eighteen carbon atoms.
Just like glucose, fatty acids are cleverly packaged so that large numbers of them can be stored without taking up too much space. You can compare it to a zip file on your computer. This is why fatty acids are stored in bunches of three in the form of what are known as ‘triglycerides’.
Thousands of tightly packed triglycerides are stored in a single fat cell. This is a huge amount of fuel, a real goldmine. As soon as you haven’t eaten for a few hours, or if you’ve been physically active for an extended period of time (for example, exercising or doing housework), this fuel will be tapped into.