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Scientists: Without a sense of smell, weight loss can be achieved despite a high-fat diet


The sense of smell seems to have a massive impact on weight
Many meals not only taste good, they also smell great. Would you be ready to give up your sense of smell completely if you lost weight? Researchers have now found that mice that lose their sense of smell lose weight. This effect also occurs when the animals eat a high-fat diet that usually leads to weight gain.

The researchers at the University of California, Berkeley and the Max Planck Institute for Biology of Aging in Cologne found in their study that mice lose weight without a sense of smell, even if they were actually eating a high-fat diet. The doctors published the results of their study in the journal "Cell Metabolism".

Mice with no sense of smell lost about 16 percent of body fat during the study
In a group of mice, the so-called olfactory neurons were genetically modified for the study. This is how the animals' sense of smell was removed, the researchers explain. A second analysis examined mice, which had an improved sense of smell, report the experts. The animals with the sharpened sense of smell increased more during the study. In contrast, the mice without a sense of smell lost about 16 percent of their body weight, even though they ate the same high-fat food. Above all, weight was reduced in the form of body fat, the doctors add.

Manipulation of the sense of smell changes regulation of the energy balance by the brain
Before the current study, researchers suspected that mice without a sense of smell simply eat less. The animals in the experiment continued to consume the same amount of calories as the animals with an improved sense of smell. This is the first study to determine that olfactory manipulation actually changes how the brain perceives the energy balance and how the brain regulates this energy balance, explains Celine Riera from the University of California, Berkeley.

Experimental animals burned more brown fat
There were differences in nutrient metabolism, the researchers say. If the mice had no sense of smell, the animals mostly burned brown fat. In addition, the doctors were able to determine that the affected animals converted the white fat of the body into brown fat. The findings of the investigation now lead to the question of whether the same results can also be achieved in humans.

A lack of sense of smell led to increased adrenaline levels in animals
Animals without a sense of smell also had an increased concentration of adrenaline in their blood, the experts explain. Increased adrenaline levels activate the burning of fat in the body. The manipulated olfactory nerves are only present in the nose and maybe a non-invasive method could "clog" the nose of patients for several months and thus lead to weight loss, the authors of the study suspect.

Manipulation of the nose could help patients with obesity and overweight
Sensory systems play a major role in metabolism. Weight gain is not just a measure of calories ingested. The sense of smell also influences how these calories are perceived, explains author Andrew Dillin from the University of California, Berkeley. The researchers hope that future work in this area will one day help patients who are morbidly obese or overweight. People with health problems such as diabetes could also benefit from the results, the expert explains.

Results could lead to new treatment options in the future
The findings could open up new treatment options for overweight patients who, for example, have already considered gastric reduction, say the scientists. With this small group of people, wiping out the sense of smell for a period of six months could make them lose weight easily and effectively. “At some point we hope to find a way to reproduce the results found in humans. In this way, the metabolism of those affected could be switched from fat deposition to fat burning, ”added Riera. (as)

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