If you've ever lost weight and then watched in horror as it came back over time, you're not alone. The phenomenon known as the "no-no effect" is a struggle that many people are familiar with, but the problem may not be simply food or exercise. Fat cells have a kind of "memory" of obesity, which makes them behave as such even after you've lost weight.

Fat doesn't forget easily.

In people who have been obese, some genes in fat cells remain more active and others less active, compared with those who have never been overweight. The genes that remain active are associated with the formation of fibrous tissue (a type of tough tissue, as if the cells have been “wounded”) and inflammation. Meanwhile, the genes that function less are those that help fat cells function normally.

The surprising thing is that these molecular changes persist even after the person has lost weight through surgery. So, even though the weight drops, the fat cells still "think" they are in the body of an obese person.

What does this mean for those who want to maintain their ideal weight?

The bad news is that these epigenetic changes may be why it's so hard to keep the weight off after you lose it initially. The even worse news is that scientists aren't yet sure whether these changes are permanent or reversible. If you're thinking about going on a crash diet, preventing excess weight gain in the first place is easier than trying to lose it and keep it off.

But there is also a positive side: with this information, doctors and health experts can create more effective weight loss programs. In the future, drugs may even be developed that help "erase" the memory of fat. Until then, it remains an open challenge for those who want to maintain a healthy weight.

Sources: Nature

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