Fat cells were found to retain a long-lasting "memory" of obesity making it hard to maintain weight loss results.
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For many, losing weight can be a challenging journey with most people who lose a lot of weight eventually regaining it.
Known as the “yo-yo” effect, several theories have attempted to explain why keeping weight off is hard, including one suggesting that a decrease in metabolic rate due to low-calorie intake could be behind it.
A new study conducted by researchers at ETH Zurich in Switzerland provides a molecular explanation for this phenomenon.
Published in the journal Nature, the study found that the body’s fat cells retained a “memory” of obesity even after weight loss, due to the long-lasting effects of epigenetics, which refers to changes in how genes work based on lifestyle and environment.
When a person is overweight, their fat cells may develop epigenetic markers that remain even if they lose weight later.
As a result, the fat cells’ normal functioning was impaired and their way of storing fat and responding to dietary changes remained unchanged from when the person was obese.
‘Avoid being overweight’
To reach these findings, the researchers studied fat tissue samples from people who had undergone weight-loss surgeries like gastric bypass or stomach reduction.
They found that the fat cells of the participants behaved similarly to when they were overweight, even after two years post-surgery.
The researchers also conducted an experiment on mice, where they analysed their fat cells before and after weight loss.
They first made the mice obese by feeding them a high-fat diet and switched to a standard one to induce weight loss.
The researchers found that making the mice obese caused specific changes to their fat cells that continued even after the weight loss, acting as a “memory” of the previous obese state.
The mice with these changes regained weight faster when reintroduced to a high-fat diet, and it was easier for them to become obese again.
While the researchers haven’t looked into how long this cell memory lasts, Laura Hinte, co-author of the study, said that these fat cells are “long-lived” ones that survive “for ten years before our body replaces them with new cells”.
“It’s precisely because of this memory effect that it’s so important to avoid being overweight in the first place. Because that’s the simplest way to combat the yo-yo phenomenon,” Ferdinand von Meyenn, co-author of the study and a professor of nutrition and metabolic epigenetics at ETH Zurich, said in a statement.
