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Fat cells are considered a nuisance because they give us bellies and flapping upper arms. But without fat our species would have gone extinct long ago.
Text by science writer Atlant Bieri
Photography by Martin Oeggerli
This is your beer belly, your orange skin and your double chin – that’s a fat cell. If you tremble with rage now and want to tear each of them out, take a deep breath please. They are not enemies, they are friends. Because without fat, you would not survive the next Sunday stroll.
Researchers consider fat even as an organ, like the kidney, lungs or heart. Its main function is to store energy. In times of oversupply of food, we store fat and in times of food shortage, we break down fat, so that our body can produce energy. This process can take place several times a day, for example, when you arrive late for lunch and your stomach is rumbling.
This is how it works: When we ingest food, the fat in the sandwich, steak or yogurt gets into our bloodstream as fatty acids. These are long carbon chains, chemically similar to those in gasoline or diesel. Fatty acids are the fuel of the human body so to speak, from which it gets chemical energy to drive each individual cell. After lunch there is an oversupply of fatty acids in the blood. Under such conditions, the muscles and other tissues may be damaged, just like an engine drowns when it gets too much fuel. Here, the fat cells come into play.
Each of them is connected with the blood stream by at least one capillary and thus filters out excess fatty acids. This turns the fat cells into a fuel valve that allows only a limited amount of diesel into the engine. The rest is saved for later. For this, always three fatty acids are chemically stuck together, which results in a compound called triglyceride. As a fat cell fills itself up with more and more triglyceride, it expands like a bun in the oven. Conversely, when we need energy and not immediately have some food available, the fat cells split some triglyceride into fatty acids and transfer them to the blood stream, which takes them to the muscles. As a result, the fat cell shrinks.
Thanks to this system, many mammals survive a winter in the first place. During summer, bears, marmots and bats eat a lot and store excess energy as fat deposit, which they live off in the cold season. But the true masterpiece of fat cells is us. Our global spread was only possible because our bodies are equipped with fat cells. This way we were able to gorge ourselves on a mammoth and then walk or paddle for days and weeks without much food for hundreds of kilometres.
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