GS Paper - III

Keeping weight off can be hard. Often it feels like you’re fighting with your body to keep the weight off after months of successful dieting and exercise. A new study has discovered why — and it’s all down to fat cell “memories.” The research, published in the journal Nature, found that fat cells have a kind of biological memory of past obesity and strive to return to this state.

What the study found?

• The study found that it wasn’t the number of fat cells that change when a person gains weight, but rather how existing fat cells store nutrients.
• This “obesity memory” can last for years after a person has lost weight, making them more prone to gain weight again.
• Our study indicates one reason why maintaining body weight after initial weight loss is difficult.
• It means that one would have to ‘fight’ this memory to maintain body weight,” said Ferdinand von Meyenn, a co-author of the study, who heads a group at the Institute of Food, Nutrition and Health, ETH Zurich, Switzerland.

Yo-yo effect of weight gain due to fat cells

• The researchers discovered these “fat cell memories” by examining fat tissue taken from people with obesity before and after undergoing weight-loss surgery. They compared this fat tissue with individuals who had no history of obesity.
• Some genes were more active in the obesity group’s fat cells than in the control group. These genetic changes lasted long after their weight-reduction surgery.
• This led the researchers to find that the molecular memory in fat cells was due to epigenetic changes to the genome.
• Epigenetic changes occur when gene expression is altered by our environment — meaning that rapid weight gain isn’t necessarily inherited, but can also be a result of events we experience in life.

Memory-primed fat cells store nutrients differently

• Additional research by the group found that fat cells from obese mice responded to food differently than cells from non-obese mice.
• In mice, we observed that formerly obese mice regain weight faster when presented with a high caloric diet.
• In humans we have found indirect evidence of this kind of memory as well,” said the study’s co-author Laura Hinte, an expert in nutrition and metabolic epigenetics at ETH Zurich.
• This suggests that the memory of obesity primed these fat cells to get larger faster and to take up more nutrients.

How long do fat cell memories last?

• The study authors said it was possible that fat cell memory fades with time but that it was unclear how long this takes.
• In the timespan we looked at — 2 years in humans and 8 weeks in mice — we still found changes that persisted in cells of the adipose tissue.
• It is possible that these will be erased over a longer period of weight maintenance.
• Human fat cells live for around 10 years, which means it could take 10 years for the obesity memory in cells to vanish.
• Currently, there are no pharmacological interventions that could cause fat cells to “forget” their bias towards nutrient storage.