Men may eat more in summer because sunlight makes them hungrier

There is a person by the name ofClare Wilson.

The sunny summer months are when men eat more calories than women, even though winter is seen as the time to fill up with comfort food.

According to Carmit Levy at Tel Aviv University in Israel, sunlight may make the skin release an appetite-stimulating hormone.

Experiments in which male mice were exposed to UV light ate more food surprised Levy and her team.

The researchers used existing data on 3000 people who had filled in detailed questionnaires as part of the Israeli government's regular health and nutrition survey. During the months of March and September, men consumed 17 per cent more calories than they did during the rest of the year.

Ghrelin seems to be the only hormone that stimulates eating and it is influenced by many systems. It was believed to be released from the stomach when empty. The brain is told to eat more by it.

Exposure to UVB radiation, which is present in sunlight, raised the levels of ghrelin in the mice's skin. The effect was not seen in the female mice or the women because of the female sex hormone oestrogen blocking it.

The skin samples that were taken from men were exposed to the UV light in the lab and they showed a boost in ghlin.

The skin hadn't been thought to be involved in appetite before. She says it would be exciting if it was true.

It's not clear why the effect happens, but it may be an adaptive response to fuel more physical activity in the summer. The biggest organ of the body is the skin, so it makes sense that it can sense the environment and go out now.

The team doesn't know if the higher food intake causes men to gain weight.

Nature Metabolism was published in the journal.

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