The Surprising Reason You Can’t Keep the Weight Off

Mar. 15, 2025

Stock image of someone weighing themselves.Photo:Getty

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There’s a reason it’s so hard to keepweight off— and it has nothing to do withyour dietor how often youexercise.That’s because your cells remember being obese and actively fight against your efforts to keep the weight off, according to a study published inNature.“The body seems to retain an obesogenic memory that defends against body weight change,” said the study, which tracked the progress of formerly obese mice and discovered that they gained weight more quickly than mice without a history of obesity when both were put on a high-fat diet.​​“From an evolutionary perspective, this makes sense. Humans and other animals have adapted to defend their body weight rather than lose it, as food scarcity was historically a common challenge,” Dr, Laura Hinte, first author on the study, said, according toThe Guardian.Stock image of a person on a treadmill.GettyAnd the propensity towards obesity is happening on a molecular level, as Professor Ferdinand von Meyenn, a senior author on the study at the Federal Institute of Technology in Zurich, said, the outlet reports: “Our study indicates that one reason maintaining body weight after initial weight loss is difficult is that the fat cells remember their prior obese state and likely aim to return to this state. The memory seems to prepare cells to respond quicker, and maybe also in unhealthy ways, to sugars or fatty acids.”And that, the study says, leads to “problematic ‘yo-yo’ effect often seen with dieting,” as people need to actively fight against their cellular memory.The PEOPLE Puzzler crossword is here! How quickly can you solve it? Play now!Stock image of a woman lifting weights.GettyHowever, researchers said the memory may not be permanent.“It’s possible that maintaining a reduced or healthy body weight for long enough is enough to erase the memory,” Hinte said, the outlet reports.As the study says, “targeting these changes in the future could improve long-term weight management and health outcomes” as “obesity and its related comorbidities represent substantial health risks.“Never miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

There’s a reason it’s so hard to keepweight off— and it has nothing to do withyour dietor how often youexercise.

That’s because your cells remember being obese and actively fight against your efforts to keep the weight off, according to a study published inNature.“The body seems to retain an obesogenic memory that defends against body weight change,” said the study, which tracked the progress of formerly obese mice and discovered that they gained weight more quickly than mice without a history of obesity when both were put on a high-fat diet.

​​“From an evolutionary perspective, this makes sense. Humans and other animals have adapted to defend their body weight rather than lose it, as food scarcity was historically a common challenge,” Dr, Laura Hinte, first author on the study, said, according toThe Guardian.

Stock image of a person on a treadmill.Getty

And the propensity towards obesity is happening on a molecular level, as Professor Ferdinand von Meyenn, a senior author on the study at the Federal Institute of Technology in Zurich, said, the outlet reports: “Our study indicates that one reason maintaining body weight after initial weight loss is difficult is that the fat cells remember their prior obese state and likely aim to return to this state. The memory seems to prepare cells to respond quicker, and maybe also in unhealthy ways, to sugars or fatty acids.”

And that, the study says, leads to “problematic ‘yo-yo’ effect often seen with dieting,” as people need to actively fight against their cellular memory.

The PEOPLE Puzzler crossword is here! How quickly can you solve it? Play now!

Stock image of a woman lifting weights.Getty

However, researchers said the memory may not be permanent.

“It’s possible that maintaining a reduced or healthy body weight for long enough is enough to erase the memory,” Hinte said, the outlet reports.

As the study says, “targeting these changes in the future could improve long-term weight management and health outcomes” as “obesity and its related comorbidities represent substantial health risks.”

Never miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

source: people.com