The role of epigenetics
Our DNA is an instruction manual for our bodies, it’s what we inherit from our parents, but DNA doesn’t work in isolation. There are tiny chemical “switches” attached to our genes that can turn them on or off. These switches are influenced by our environment, diet, and health. The process of switching certain genes on and off is called epigenetics. “Epigenetics tells a cell what kind of cell it is and what it should do,” said Laura Hinte, a doctoral researcher at ETH Zurich. And the thing is, once a switch is pulled, the resulting changes can persist for years or even decades, affecting how our cells function.
Fat cells have a long memory
Researchers at ETH Zurich conducted a study on mice to explore what causes the yo-yo effect on a molecular level. They found that obesity leaves lasting epigenetic marks on fat cells, even after weight loss. These marks essentially program the fat cells to return to their overweight state when exposed to a high-fat diet again.
“The fat cells remember the overweight state and can return to this state more easily,” explained Prof. Ferdinand von Meyenn. This discovery provides a scientific basis for why so many dieters struggle to maintain their weight loss in the long term.
The research team also examined human fat tissue samples from individuals who had undergone weight-loss surgeries, such as gastric bypass procedures. The results supported the findings from the mice study, epigenetic changes linked to obesity remained in fat cells even after substantial weight loss, suggesting that this memory effect exists in both animals and humans.
Another reason why maintaining weight loss is so difficult
Weight regain after dieting has long been attributed to metabolic adaptation, hormonal changes, and behavioural factors such as emotional eating. However, the discovery of an obesogenic memory in fat cells introduces a new layer of complexity, yet another thing that is stacked against people trying to lose weight. “Fat cells are long-lived cells. On average, they live for ten years before our body replaces them with new cells,” Hinte says.
Additionally, researchers suspect that fat cells may not be the only ones with this memory. “Other body cells might also play a part in the yo-yo effect,” von Meyenn says. Cells in the brain, blood vessels, and other organs could contribute to weight regain, making long-term weight management even more difficult.
Is there a way to erase this fat cell memory?
While this research provides a deeper understanding of why weight loss is so difficult to maintain, it also opens new avenues for future treatments. Scientists hope that targeting these epigenetic markers could one day lead to therapies that make weight loss more sustainable. As of now, there are no drugs or therapies available to erase the epigenetic memory of obesity. “Maybe that’s something we’ll be able to do in the future, but for the time being, we have to live with this memory effect,” said Laura Hinte.
What’s the best way to maintain weight loss long-term?
Unfortunately, this study doesn’t give us a simple solution. But it helps us understand and maybe have more compassion for people struggling with weight loss, including ourselves. The fat cell memory is just one more thing we have to battle against.
For now, if you want to avoid the yo-yo effect, your best path forward are gradual, sustainable lifestyle changes rather than extreme dieting. A balanced diet, regular physical activity, and long-term behavioural changes with professional and social support remain the best strategies for managing weight.