Weight: Lean through intestinal bacteria?

The intestinal flora of thin and fat people is different. However, this does not result in a simple weight loss concept

A question of germs: Studies have shown that when you are overweight, the ratio of certain bacteria shifts: the more pounds, the fewer Bacteroides strains and the more Firmicutes. This influences how well we utilize certain parts of the food. Signals to our brain also have an influence on our appetite

© W & B / Martina Ibelherr

Can you transplant obesity? US researchers succeeded in a surprising experiment: They implanted the intestinal flora of twin sisters in mice raised aseptically - slim one, overweight the other. After that, the rodents were allowed to eat a high-fat diet like a ball. But only the mice that carried the fat sister's microbes became overweight themselves.

"That opened the eyes of many in the research world," says Professor Christian Sina. At the Institute for Nutritional Medicine at the Schleswig-Holstein University Hospital in Lübeck, he is researching individual nutritional therapies that include the microbiome. It has been known for a long time that the colon colonization of thick and thin people differs.

The twin experiment now suggests that a changed microbiome can actually lead to obesity. "There are also indications from case reports after a stool transplant," says Sina. Weight gain occurred as a side effect.

Individual microbiome

So all you need is the right mix of microbes and the pounds drop? Experts see little prospect of a simple solution. "The influence depends very much on the genetics, the disposition of each individual," explains Dr. Siegfried Ussar, who researches the relationship between the microbiome and obesity at the Helmholtz Institute in Munich.

Eating too much salt can damage the microbiome and lead to weight gain

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Therefore, only a highly personalized approach promises success. Unlike in the laboratory, many environmental influences can hardly be controlled in humans. What we eat also determines which microbes feel good.

According to Ussar, it would be conceivable to support a change in diet with microbial therapy. Those who eat one-sidedly reduce the biodiversity in their intestines. "Like extinct animals in a jungle, they don't return by themselves," says Ussar. With special probiotics, they might be able to settle again.

That makes us fat

  • Hungry germs: What we eat and how much could be influenced by bacteria, researchers suspect. Namely, by influencing our appetite via signal substances
  • Too much salt: our microbiome does not get a salty diet. Synthetic sweeteners are also likely to be unfavorable.
  • Antibiotics: The drugs are still used for fattening animals in many countries. They arguably accelerate weight gain by changing the microbiome.