by Cesare Pecarisi
Skin exposed to the sun’s ultraviolet rays activates ghrelin, a fasting-triggered hormone that sends hunger signals to the brain. But estrogen disrupts the mechanism
A large international group of scholars, mainly from Israeli but also American, French and German centers, led by Shivang Parikh of Tel Aviv University, published in Nature Metabolism a study involving three thousand subjects of both sexes, evaluating all seasons and which confirms a phenomenon in humans that was previously only known from mice: when the sun is high in the sky and the temperatures rise, as in summer, hunger increases, but only in males, not in females. The reason lies in the fact that skin exposed to ultraviolet radiation from the sun’s rays activates ghrelin, a hormone produced in the gastrointestinal tract and normally induced by fasting, to send hunger signals to the brain.
nervous hunger
Ghrelin is also stimulated by stress and this explains the so-called nervous hunger and its altered release is observed in diseases such as anorexia and bulimia, which are precisely eating disorders. But why do only men and not women get a bit bulimic in summer? Sunlight activates ghrelin, which is also present in skin adipocytes, but skin also contains an oncoprotective protein called p53, which serves to protect us from the formation of skin tumors caused by excess UVB radiation from the sun.
estrogen
P53 also functions to activate ghrelin in skin adipocytes, but in women, estrogen disrupts this interaction, preventing ghrelin from triggering the resultant foraging behavior in response to UVB exposure. The skin thus becomes an important mediator of human energy homeostasis and opens up new possibilities for gender-specific topical treatment of eating disorders that exploit the endocrine basis of hunger. So if you’re hungry like wolves at the beach, you should stay longer under the umbrella and as a woman it may just be gluttony because science doesn’t justify that summertime gluttony.
July 22, 2022 (change July 22, 2022 | 14:43)
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