With the holiday season in the rearview for another year, many of us are looking at getting a fresh start and forgetting about past diet and exercise challenges.

For our fat cells, that’s easier said than done.

A new study shows that fat cells “remember” being overweight, thanks to chemical markers that control which genes are activated in our cells.

These chemical stamps make it easier for fat cells to return to their previously plump state with little effort. This evidence provides a biological reason that confirms the suspicions of many who have struggled to maintain weight loss — that even if you lose weight, it’s incredibly easy to gain it back.

Researchers said that fat cells live for about 10 years on average before being replaced by new ones, which explains the cells’ extended memory. While there are currently no medications available that can erase our fat cells’ memory, it’s an area researchers hope to study more.

In the meantime, researchers emphasize prevention through maintaining a healthy diet and exercise regimen, especially for young people. The best way to avoid regaining weight is not to gain it to begin with.

The same team is also delving into whether other types of cells, like those in our brains or blood vessels, might also harbor weight-gain memories. If that’s the case, the research could offer even more insight into why keeping the pounds off can feel like a losing battle.

While we’d like to forget about times when we were overweight, our fat cells aren’t so quick to move on. Let’s hope that as we take a stroll down memory lane after the 2025 holiday season, we won’t remember any undue weight gain.