This is known: Adolescent boys still lose weight when they are snacking on kilos of pancakes. And many older people have to "just watch food" to gain weight.
Is the "prosperity belly" 50plus unavoidable? What sounds like truism or protection claim depending on perspective, is now scientifically proven: Older people actually increase in body weight if they take the same amounts of food as in younger years.
The reason: In old age, the fat metabolism flagged and stored fat is degraded worse. Researchers from Sweden report in the journal "Nature Medicine".
Fat is stored in the body in fat cells called adipocytes. They make up about 90 percent of white adipose tissue. Fat stored in the cells is constantly being broken down and new stored. In order to examine how this metabolism changes over the course of life, the team headed by Peter Arner from the Karolinska University Hospital in Stockholm (Sweden) examined 54 people. Of these, they had twice taken a sample of adipose tissue over an average of 13 years.
The scientists studied the age of the triglycerides in the samples - fat molecules embedded in the adipocytes.
It can be ascertained in older subjects with a simple trick: Normally, the percentage ratio of the carbon isotopes C14 and C12 in all cells of living beings corresponds to the concentration of these isotopes in the atmosphere.
At the time of the supernatural nuclear weapons tests in the Cold War, however, the concentration of C14 in the atmosphere doubled between 1953 and 1970, after falling abruptly after the cessation of aboveground tests in 1980. Therefore, by comparing the percentage ratio of C14 and C12 isotopes in a fat cell, their age can be deduced - in old cells, the percentage of C14 isotopes is higher.
The study showed that with increasing age, fat loss slowed down - regardless of whether the person had gained weight, kept their weight or decreased over the years: the older the subjects became, the slower the fat cell metabolism became. And this apparently has a direct effect on the development of body weight: Subjects who had not reduced their calorie intake over the investigation period put on about 20 percent body weight.
The researchers tried to determine the influence of lipid metabolism on the development of body weight with the help of a second group of probands. The scientists also examined 41 seriously overweight people who had their stomach contracted. Again, the physicians noted a significant influence of fat loss on the development of body weight. A high rate of lipid metabolism correlated with a more pronounced weight loss than a lower lipid metabolism rate. This may suggest that the role of lipid metabolism in regulating body weight has been underestimated.
"The results suggest for the first time that there are processes in our adipose tissue that, independently of other factors, influence body weight in old age, which could open up new ways to treat obesity," says study leader Peter Arner.
However, German researchers point in their first reactions to the fact that the subject Adeposis should not be broken down to individual factors. Helmut Frohnhofen, Department of Gerontology at the Alfried Krupp Hospital in Essen, the study considered too small to draw reliable conclusions from it: "The results of the study are an interesting indication, but it is here to quite a few subjects."
Basically obesity can not always be traced back to biology: "There are many factors involved, some of them genetically, some of them behavioral, and when your age limits your physical activity, the best way to control weight is through nutrition", so Frohnhofen.
For really old people, obesity will eventually not be the most pressing problem, says Helmut Wallrafen of the German Society for Gerontology and Geriatrics: "When people gain some weight in their old age, it is more of a subjective, aesthetic problem than a medical one As a practitioner and nurse, I've been given overweight on a very selective basis, and we usually face the challenge of having people with malnutrition in old age. "