Leptin from fat cells counteracts weight loss

If you have lost weight, you will not only become lighter, but you will also decrease in volume. Where and how exactly is the fat stored and what happens to the fat when you lose weight? We have special fat cells that ensure that we can carry our supply of fuel with us, a very useful storage cupboard. However, a problem with fat cells is that it is very difficult for them to release their contents, because certain hormones are produced too much or too little.

What is obesity?

Being overweight means that you consume more energy-rich nutrients than you use in combustion, which your body stores in the form of fat. Not only glucose provides energy, but all carbohydrates that are made up of glucose, such as starch and glycogen. Fats and proteins are also energy-rich substances that we can burn. When the body stores fat, this happens in the fat cells and they then increase in size. This makes you heavier and gives you more volume.

Why do we have fat cells?

Fat cells store fat. Fats are fuels that we burn in our cells together with oxygen, which releases energy. Fat cells are located in the bottom layer of the skin, around the organs and between the cells. Fat cells have multiple functions. They store fat in the form of a drop, which becomes larger as fat is added, because fats attract each other. This causes the cells to swell and because they are swollen, the next function also becomes clear, namely that of a cushion. We have fat cells around the organs and these protect our organs. A third function is that a layer of fat acts as heat insulation. Mammals, including us humans, are warm-blooded animals, which means that they have to keep their temperature constant. Marine mammals in particular, such as whales, have a thick subcutaneous fat layer, because you cool down faster in water than on land.

Where does the fat go when you lose weight? Losing weight means you burn more nutrients than you store. This may be because you absorb fewer nutrients (eat less) or you burn more nutrients (exercise more). The reserve fat stores are burned. Just as with the combustion of glucose, the combustion of fats produces water, which you partially urinate, sweat out and exhale, and carbon dioxide, which you exhale. So the fat seems to ‘evaporate’.

Fat cells produce leptin

Research from 1995 by Friedman et.al showed that mice that could no longer produce a certain hormone developed obesity. He made the link between no longer being able to produce the hormone leptin and becoming fat. He named the hormone leptin, after the Greek word for slim (leptós), because this hormone makes you want to eat less. A lack of it makes your body think you’re starving and keep eating. There is an interplay between the fat cells and the brain: when fat cells are filled, they produce the satiety hormone leptin, which via the blood inhibits the hunger center in the brain. If fat disappears from the cells because you lose weight, the hormone decreases, signaling the brain to absorb more food.

What else do fat cells do?

The adult body has a fixed number of fat cells. The number of fat cells can increase in early childhood and adolescence if you are overweight, but once you become an adult, the amount remains the same. Fat cells work very efficiently, because in times of scarcity it is very useful to have a stock of fuels. Fat cells can indicate when they have sufficient supplies through leptin production. The problem with well-filled fat cells is that they keep asking for fat. Fat cells produce leptin, so you would think that the feeling of hunger would be suppressed. Unfortunately, this works differently, because the more leptin is made, the more insensitive the body becomes to it and the feeling of satiety disappears. The same phenomenon occurs with insulin. The more insulin you produce, the more insensitive the body becomes to it. This explains why fat people can develop type 2 diabetes, because they have become insensitive to it due to the constant production of insulin in response to eating a lot of carbohydrates, so that the cells no longer absorb and process the glucose.

Feelings of hunger and satiety

Immediately after eating you produce certain hormones. The pancreas produces the satiety hormone insulin, which ensures that glucose is absorbed into the cells, burned and the rest is stored in glycogen and fats.
People with diabetes or diabetes no longer produce insulin at all, diabetes type 1. Others do produce insulin, but they have become less sensitive to it, diabetes type 2, also called adult-onset diabetes. If you have an empty stomach again after a while, the hunger hormone ghrelin is produced in the stomach wall, which triggers the feeling of hunger. Ghrelin also causes your stomach to contract and growl. Feelings of hunger and satiety are an interplay between the amount of hormones produced.

So what’s the problem now?

People who have difficulty losing weight could have a hormone imbalance. This could also explain the so-called yo-yo effect: after losing weight, the body catches up enormously, the feeling of hunger has increased even more than before. However, those last kilos are a major problem for many. After you lose the first kilos, it becomes increasingly difficult to burn those last kilos. After all, your fat cells continue to ask for fat, because the leptin balance is still missing. Because, as it turns out, when fat cells lose fat, they have to shrink. But that apparently costs too much energy, which causes the fat cells to produce less leptin. The body therefore wants to consume more nutrition, so that the fat cells can fill up again. The body strives to waste as little energy as possible.

Possible solutions that help you lose weight

People with obesity have been given leptin, but here too the problem of insensitivity arises. The amount of leptin to be administered is still a topic of discussion, because it varies per person and circumstance, just like with diabetics and the administration of insulin. Some dietitians advocate taking a day of bunkering down one day a week, so that leptin levels rise again. However, a clear effect has not yet been measured. Other diet researchers show that the solution may lie in eating more proteins. Firstly, because proteins increase leptin sensitivity and then the feeling of satiety will increase. Secondly, because an increased protein intake lowers the ghrelin concentration, this will reduce the feeling of hunger. In addition, if an early form of diabetes develops, the body may become more sensitive to insulin, which triggers glucose conversion. All in all, the solution seems to lie in restoring the hormone balance and that could explain why some people have much more difficulty maintaining their weight and others have to continue to make an effort. Another recommendation by researchers is that the faster you lose weight, the greater the fat cell stress and the desire to retain fat. When losing weight slowly, cell stress has proven to be less.

Possible tips to lose those last kilos

Enjoy an occasional day of eating whatever you want. Eating more proteins (meat, fish, egg, soy) and losing weight slowly, so no crash diet. After all, it’s all about maintaining the satiety hormone leptin. And who knows, persistence wins!

Leptin from fat cells counteracts weight loss
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