By John Salak –
Diets all too often fail, at least over the long run. Anyone who has ever tried restrictive calorie programs probably knows this. In fact, anywhere from 65 percent to 95 percent of these programs go belly up when it comes to keeping weight off, leading those involved to embrace another attempt when pounds find their way back.
This vicious cycle is referred to as the yo-yo effect. These diets fail for a host of reasons, including poor planning, unrealistic goals and logistical considerations that make them almost impossible to stay on track. Swiss researchers claim they have now identified another culprit. Fat cells have a memory based on epigenetics, which undermines a person’s ability to keep weight off.
Epigenetics is the part of genetics that is linked to small yet characteristic chemical markers on genetic building blocks. While the sequence of building blocks has evolved over a long period of time, they are all inherited from parents. Epigenetic markers, on the other hand, are more dynamic and include environmental factors, eating habits and the condition of a person’s body (think obesity). They can change over a lifetime, but they also can remain stable for many years or decades, during which time they play a key role in determining which genes are active or inactive cells.
“Epigenetics tells a cell what kind of cell it is and what it should do,” explained Laura Hinte, a doctoral student in the ETH Zurich research group that produced the findings. Ultimately, epigenetics helps fat cells return to their chubby essence even in the face of restrictive calorie diets.
The research specifically found that obesity, at least in mice and probably in people, leads to characteristic epigenetic changes in the nucleus of fat cells. These changes remain even after a diet, making it easier to put pounds back on after they’re shed.
“The fat cells remember the overweight state and can return to this state more easily,” especially when exposed to a high-fat diet, reported study leader Professor Ferdinand von Meyenn. “That means we’ve found a molecular basis for the yo-yo effect.”
While the ETH Zurich researchers focused on mice, they 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. The review ultimately yielded results consistent with those of the mice.
What remains unclear is how long fat cells can remember obesity. The researchers noted, however, that fat cells, on average, live for ten years before they are replaced. In perhaps another hurdle, it is not currently possible to erase the epigenetic memory of these cells.
“Maybe that’s something we’ll be able to do in the future,” Hinte said. But for now, the impact of fat cell memories remains an issue.
“It’s precisely because of this memory effect that it’s so important to avoid being overweight in the first place. Because that’s the simplest way to combat the yo-yo phenomenon,” von Meyenn stressed. He also noted that other cells in the brain, blood vessels or other organs may also remember obesity and contribute to supporting the yo-yo effect.
Either way, the best way to avoid yo-yo weight gain is to try to keep the pounds off to begin with.
