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Fat cells are programmed by excess weight to store a lot of fat and signal hunger. Losing weight doesn’t change that. Now it is clear that a yo-yo phase does not simply arise from a lack of discipline.
In the fight against obesity, the scales become the beloved or hated referee.
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After a diet, something has been achieved: Unnecessary pounds are gone, many blood values have improved, and the achieved goal makes you happy and proud. But then everyday life starts and with it the dreaded yo-yo effect – the fat deposits grow again. New research shows that a driving force behind this is a genetic program in fat cells. The study by researchers at ETH was recently published in the journal «Nature» published.
When you are overweight, fat cells adjust many of their genes to ensure that there is an abundance of energy. “In mice in this situation, small molecules are attached to some genes, while in others existing appendages are removed,” explains Ferdinand von Meyenn, lead author of the new study, in an interview. In technical jargon, the pattern of appendages is called an epigenetic pattern. These changes cause some genes to be more active, while others are switched off.
Gene activity is altered by obesity
In overweight mice, the fat cells are programmed, among other things, to constantly store a lot of fat. They puff up. In addition, more new fat cells are formed. This means that more fat can be stored overall. At the same time, the fat cells reduce their basal metabolic rate. After all, you no longer have to make any special effort to build your own fat molecules; you can get them delivered free to your door all day long.
Unfortunately, the animals’ fat cells retained the epigenetic pattern of the overweight phase even after a diet. The fat cells did not switch back to normal mode. They were still programmed for energy to be in abundance. Since every cell was larger than before and there were more fat cells in the tissue, the hunger for fat was excessive.
“We are convinced that this excess weight memory is also switched on in human fat cells when they gain weight and continues to exist after the diet,” says von Meyenn. The team did not determine the epigenetic patterns of human fat cells. But they looked in detail at their gene activity before and after a diet. “We saw the same activity patterns in human fat cells before and after a diet as in mice.”
In mice, the cause of the gene activity is the epigenetic patterns, emphasizes the epigenetics expert. So it is absolutely plausible to assume that human fat cells continue to be programmed to constantly absorb fat after weight loss.
It’s probably not just the fat cells that build up such an excess weight memory. Fat cells are just parts of a large team that organizes food intake and cellular storage. This is how fat cells send signals to the brain. Certain regions then release hormones that control feelings of hunger or satiety. They probably also remain programmed for increased fat storage after a diet. The ETH team will now analyze this.
How can we modulate gene activity?
From a physiological point of view, the storage of fat and other cells makes perfect sense. Throughout almost the entire development of humanity, phases of oversupply and shortage of food have alternated. So the body had to prepare itself to store reserves for the tough times and develop genetic programs to control this.
The problem today is that in many countries there is a constant oversupply of food. In order to stay slim, we have to be careful not to consume more energy than our body needs. We cannot simply end the stockpiling program.
The new findings do not provide the switch for this either. But they can help combat the yo-yo effect in a targeted manner. It is known that factors such as physical activities or some foods modulate various epigenetic patterns.
It is still unclear whether swimming at six in the morning, cycling at eight in the evening or blueberries for lunch – to name just a few examples – influence the memory of excess weight. Given the complexity of the processes, it is to be expected that only a combination of different factors will be promising. But now that a molecular cause of the yo-yo effect is known, experts can search for the recipe for success in a much more targeted manner than before.
Losing weight is definitely healthy
Knowledge about the genetically anchored overweight memory also eliminates the stigma that burdens many people in the yo-yo phase. If you gain weight after a diet, it is often said that you are weak-willed and that you should pull yourself together now that you have achieved such success and eat normally.
But it is precisely this wish that those affected undoubtedly have that the programming of the cells counteracts. The epigenetic patterns of the fat cells constantly signal an excessive need for fat. Since the fat tissue is larger overall than before, there are a lot of fat cells doing this. The brain converts this flood of signals into an excessive feeling of hunger.
Previously overweight people have to resist this very strong internal command all day long after a diet. And if they don’t sleep well, even at night. This requires enormous discipline. It is questionable whether someone can completely resist their body’s commands without medication.
What makes matters worse is that after a diet, less energy is generally required than before due to changes in metabolism and often lower muscle mass. This means that a person has to eat significantly less to stay slim. The yo-yo effect also occurs when someone only slightly reduces the amount of food they eat.
There is definitely one consolation: losing weight with a balanced program is healthy. If you gain weight again at some point, you should start another weight loss project – as annoying as that is.
How does epigenetics influence weight memory in fat cells after weight loss?
1. What are the key genetic changes that occur in fat cells during obesity and how do these changes cause excessive fat storage and reduced metabolic rate?
2. How does the excess weight memory persist in fat cells even after weight loss? Can you explain the role of epigenetics in gene activity regulation in this context?
3. What factors contribute to the development of the yo-yo effect, and how might targeting epigenetic modifications help individuals overcome this?
4. Can you discuss the challenges individuals face in maintaining weight loss, particularly in terms of changes in metabolism and hunger signals from the body?
5. How can we foster a more empathetic understanding of weight gain and the struggle to maintain weight loss?
