After much effort weighing your food, meticulously planning your meals and scrutinizing your food intake, the diet seemed to have paid off. But a few weeks or months later… Patatras. The kilos have returned to their quarters, heavier than before. You are a victim of the famous yoyo effect: this tendency to regain the weight lost after a slimming diet. Don’t blame yourself. This phenomenon is difficult to control, according to a study published on November 18 in Nature.
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Adipose tissue, one of the main culprits
The explanation is partly to be found in adipose tissue, at the level of adipocytes, these cells which store fat in the body. Researchers from the Swiss Federal Institute of Technology in Zurich (Switzerland) studied the molecular mechanism of the yoyo effect and discovered that epigenetics could explain this weight return after a restrictive diet.
Epigenetics studies changes in gene activity, which is how the broader environment changes the expression of our genes (without changing the genetic sequence). Our behaviors (tobacco, alcohol), environmental factors (stress, pollution, etc.) and the state of our body (including overweight or obesity) send signals which, via biochemical markers, modulate the activity of Genoa. “Epigenetics tells a cell what type of cell it is and what it should do,” explains Laura Hinte, a doctoral student who participated in the study led by Ferdinand von Meyenn, professor of nutrition and metabolic epigenetics at ETH Zurich.
Fat cells remember excess weight
What is the relationship between epigenetics and the yoyo effect, you might ask? Scientists suggest that fat cells have epigenetic memory.
To understand this, the team analyzed fat cells from overweight mice and mice that lost weight after dieting. The results show that being overweight or obese leads to specific epigenetic modifications in the nucleus of adipose cells. Changes that persist even after a diet. “One of the reasons why it is difficult to maintain body weight after initial weight loss is that fat cells remember their previous obese state and probably seek to return to that state,” deciphers at Guardian Ferdinand Von Meyenn, director of the study.
The researchers noted that mice with the epigenetic markers of obesity regained weight more quickly when they ate. “This memory appears to prepare cells to respond more quickly, and perhaps also in unhealthy ways, to sugars and fatty acids.” These memories would therefore explain why the body resists attempts to lose weight.
This biological memory mechanism is also verified in humans, the researchers have succeeded in proving. They observed this by analyzing adipose tissue biopsies from obese people, before and after weight loss following bariatric surgery. The tissues were then compared to adipose tissue from healthy people without weight problems.
An erasable cellular memory of obesity?
Knowing that epigenetics is a phenomenon that is in principle reversible, a question arises: do fat cells remember being overweight or obese ad vitam aeternam or is it possible to go back in time? Researchers do not yet have the answer. They don’t know how long cells keep this memory of extra pounds. However, they point out that fat cells are long-lived cells. “On average, they live ten years before our body replaces them with new cells,” the researchers point out in a press release.
Erasing the epigenetic memory of cells is not a credible hypothesis either: it is currently impossible to modify the relevant epigenetic marks in the cell nucleus using drugs, point out the authors of the study.
Yoyo effect: other body cells potentially complicit
This work is the first to show that fat cells have an epigenetic memory of obesity. But they do not exclude that other cells in the body have such a memory and could play a role in the yo-yo effect. Could brain cells, blood vessels or other organs also be complicit in the return of unwanted pounds? This is what researchers hope to discover in future studies.
Source:
https://www.nature.com/articles/s41586-024-08165-7
https://medicalxpress.com/news/2024-11-fat-cells-epigenetics-based-memory.html
https://www.theguardian.com/society/2024/nov/18/ability-fat-remember-obesity-drives-yo-yo-diet-effect
