The study found a memory in the fat cells, which is why dieters quickly gain weight back

The body fat cells carry the memory of obesity long after losing weight. That may help explain why the weight usually returns to the former readings and even more.

This is what was published in the journal Nature on Monday research.

It has long been known that dieters have a strong tendency to gain weight back. Several reasons have been found for this.

As a result of dieting, for example, the secretion of satiety hormones decreases and the secretion of hunger hormones increases.

In addition, the dieter’s body tries to slow down the metabolism so that so much energy is not consumed.

During severe dieting, a person also loses muscle mass, and the smaller muscles consume even less energy.

A new study tells what happens in fat tissue at the molecular level when a person gains weight and loses weight.

Research team looked at the adipose tissue of morbidly obese people. Morbid obesity is classified when the body mass index is over 40.

In their fat cells, some genes function more actively than in the comparison group that remained at a normal weight all their lives, while other genes are more muted.

Among other things, the genes activated by obesity accelerate inflammation and fibrosis, i.e. the formation of stiff scar-like tissue.

Even bariatric surgery did not restore cell function to normal. Two years after the surgeries, the subjects’ weight had dropped enormously, but the genes functioned the same as before the surgery.

The researchers found the same in mice that were first fattened and then thinned.

The fat cells of the emaciated mice absorb more fat than the cells of the controls. Obese and emaciated mice put on a high-fat diet gained weight faster than controls that had never been obese.

In a mouse study found out in particular that obesity-related changes occur in the epigenome of fat cells, i.e. in the regulation of genes. The changes remain for months even after losing weight.

It is certainly not known how long they will last, says the epigenome researcher Ferdinand von Meyenn from the ETHZ University of Zurich For Nature magazine.

“Somewhere in the time window, the memory may disappear. We don’t know.”

The result means that the dieter may need help for a long time to maintain the new weight, says one of the authors of the study, a biologist Laura Hinte ETHZ:sta.

Helsinki the university’s clinical metabolism professor and obesity researcher Kirsi Pietiläinen commented on the research, saying that its great merit is the examination of different cells separately, since each cell type has its own epigenetics.

Pietiläinen has himself studied the mitochondria of adipose tissue, a kind of cellular power plants or internal combustion engines. Gaining weight weakens mitochondrial function.

Pietiläinen’s group found that even dieting no longer rejuvenates them. On the contrary, dieting turns down the genes that control mitochondria and thus apparently depresses the energy consumption of fat cells.

“It could be that the adipose tissue prepares itself to grow again in this way.”

Pietiläinen points out that the central part of regaining weight is the brain.

The brain interprets that the dieter has received too little energy for a long time, initiates energy saving in all organs and commands the person to eat more food.

Correction November 20 at 9:15 a.m.: ETH Zürich university abbreviation (ETHZ) corrected, was initially erroneously EHT.