You could call it the beer garden effect: sitting outside with a beer usually means ordering something tasty to eat after all. Even if you didn’t feel hungry beforehand. It’s not because of the beer, it’s because of the sunshine, at least if you’re a man. Researchers have found that the sun makes men hungry.

Intensified fat and steroid turnover in male subjects

It all started when Shivang Parikh and his team at Tel Aviv University evaluated an Israeli nutritional study. The study with 3,000 subjects showed that men consume more calories per day in the summer than in the less sunny second half of the year. This effect was not seen in women. The scientists then put together a mixed group of subjects who each received 25 minutes of UVB radiation per day. In fact, the men among them felt more hungry after each treatment, while the women did not. The analysis of blood samples revealed an intensified exchange of fat and steroids in the male participants.

Estrogon inhibits ghrelin release, while testosterone increases it

The researchers used main samples and mice to get to the bottom of the matter. In these experiments, they observed that certain fat cells in the subcutaneous tissue release the hunger hormone ghrelin into the blood when exposed to UVB radiation. But before that, there was increased p53 production: This protein is involved in the skin’s repair process when DNA damage occurs, for example due to UV exposure. p53 stimulates ghrelin production. The male hormone testosterone reinforces the effect, while the female hormone significantly inhibits ghrelin release.

Now there is the assumption that UV light and other environmental influences trigger further effects that we do not yet know. Research will continue accordingly, mainly to explore the possibilities of phototherapy. For example, if men suffer from a pathological loss of appetite, something could probably be changed with UVB radiation. The future will show which changes in behavior are possible.

Source: scinexx.de