When we want to lose weight, whether for health reasons or to conform to certain aesthetic criteria, it is common that after a drop in the number of kilograms displayed by the scale, this figure ends up gradually rising to little. This can give the impression that the efforts made (change in diet, more regular sporting activity, surgical operation, etc.) were of no use.
Little by little, science is better understanding the reasons for this yo-yo effect, which can be quite discouraging for those who cannot stabilize. Selon New Scientistthere is perhaps not much to do, except to try to accept one’s condition, since the return of the lost kilos (or at least part of them) could essentially be due to lasting changes in the DNA and RNA of fat cells, which store fat in the body.
The scientific media notably cites a study stating that around 85% of overweight people who lose at least a tenth of their weight resume it in the following yeart. This can partly be explained by the fact that it is difficult to maintain a low-calorie diet over a long period of time, but this explanation is not entirely satisfactory, explains Laura Catharina Hinte of the Swiss Federal Institute of Technology in Zurich.
Genetic memory
According to the specialist, if the problem was solely linked to the difficulty of maintaining a healthy or even austere diet, the percentage would not be as high: “It’s impossible that we all don’t have enough willpower to keep the weight off.” Other reasons can be given, including the fact that the brain may consider a sharp drop in body fat index as dangerous. Studies show that in response, it then behaves by making the body burn less energy.
With her team, Laura Catharina Hinte studied the adipose tissue of twenty people, which was taken from them just before the bariatric operation they underwent – this is an intervention aimed at shrinking the stomach in order to make the feeling of satiety occurs more quickly. For comparison purposes, a new sample was then taken two years later from these people who had lost at least a quarter of their initial mass. At the same time, similar samples were taken from eighteen people with a BMI considered normal.
The researchers noticed that, two years after the first samples, there were still very notable differences between the quantity of RNA molecules (responsible for protein coding) present in obese (or formerly obese) people and that noted in others. Their conclusion is as follows:: weight changes tend to permanently increase inflammation in fat cells and disrupt the way they store and burn fat.
Additional tests carried out by the same team on mice also show that those which had experienced significant weight loss were more likely to gain weight again. On a similar diet, the previously obese mice gained 14 grams per month, compared to 5 grams for the others.
Finally, the scientists discovered that molecular markers, or epigenetic marks, present on the DNA of fat cells appeared to be responsible for the RNA changes linked to obesity. This confirms that in the future, research should focus more on developing drugs that target epigenetics, that is, how the environment can change the way genes work. This could be an effective aid in combating untimely weight gain.
Source: www.slate.fr
