A friend at work seemed to always be on a diet. Atkins, cabbage soup diet, grapefruit diet, keto… You name it; she tried it all.

While she was always successful at losing weight, it always came back a few months later, along with a couple of extra pounds. Talk about frustrating!

Given how good she was at sticking to whatever diet she was following, we could never figure out why she struggled with weight cycling.

Now, a team of researchers at ETH Zurich may have hit upon the reason behind this “yo-yo effect” — and it has nothing at all to do with willpower…

Fat cells remember how to put the weight back on

Unlike genetic markers, epigenetic markers are more dynamic; they can be changed throughout a person’s lifetime by factors such as environment, eating habits and body conditions like obesity.

ETH Zurich researchers decided to look for the molecular causes of the weight-loss “yo-yo effect” — also known as weight cycling — by analyzing fat cells from overweight mice and those that had shed their excess weight through diet.

They found that obesity leads to characteristic epigenetic changes in the nucleus of fat cells and that these changes persist even after a diet.

“The fat cells remember the overweight state and can return to this state more easily,” says research lead Ferdinand von Meyenn, a professor at ETH Zurich.

The researchers showed that mice with these epigenetic markers regained weight more quickly when they once again had access to a high-fat diet.

The team also found evidence for this mechanism in humans by analyzing fat tissue biopsies from formerly overweight people who had undergone stomach reduction or gastric bypass surgery. In these samples, the researchers analyzed gene expression rather than epigenetic markers. However, the results were consistent with those of the mice.

How long do fat cells remember

The researchers have not investigated how long fat cells can “remember” obesity. But they typically live for ten years before the body replaces them with new cells. That’s potentially ten years of epigenetic “memory” that makes weight cycling easier.

Unfortunately, it’s impossible to change the relevant epigenetic markers that could erase those memories from fat cells.

“Maybe that’s something we’ll be able to do in the future,” says Laura Hinte, a doctoral student in the research group. “But for the time being, we have to live with this memory effect.”

Von Meyenn adds that this memory effect is precisely why it’s so important to avoid being overweight in the first place. “… That’s the simplest way to combat the yo-yo phenomenon,” he says.

It’s easy to take these findings to mean that losing weight and keeping it off is a hopeless battle. But that’s far from their intention.

They hope that children and young people can focus harder on preventing obesity to avoid the difficulty we’ve learned about fat cell memory.

But for adults already dealing with weight problems, the only answer is avoiding the yo-yo train that just reinforces fat cell memories over and over again.

If whatever you’re doing to lose weight is working, that’s great — but once it’s off, it’s time to shift gears. Here is where you need to change what you’ve done in the past. Keeping the weight off requires a different approach that focuses more on exercise and less on calories.

Sources:

Cause of the yo-yo effect deciphered — EurekAlert!

Adipose tissue retains an epigenetic memory of obesity after weight loss — Nature