Sun exposure increases appetite in men, but not women

A new study from Tel Aviv University reveals that exposure to the sun can increase appetite in males, but not in females. The research unravels the differences between males and females in the activation of the metabolic mechanism. 

Sun exposure in males activates a protein called p53 to repair DNA damage in the skin caused by the sun. This signals the body to produce a hormone called ghrelin, which stimulates the appetite. In females, on the other hand, estrogen blocks the interaction between p53 and ghrelin and does not create the same urge to eat after sun exposure. 

The study was led by Professor Carmit Levy and PhD student Shivang Parikh, in collaboration with many researchers in Israel and around the world. 

The analysis was focused on epidemiological data collected in a year-long survey about the eating habits of 3,000 individuals of both sexes. This data combined with the results of a genetic study in a lab model. 

The findings identify the skin as a primary regulator of energy and appetite (metabolism) in both lab models and humans.

“We examined the differences between men and women after sun exposure and found that men eat more than women because their appetite has increased. Our study was the first gender-dependent medical study ever conducted on UV exposure, and for the first time, the molecular connection between UV exposure and appetite was deciphered. Gender-dependent medical studies are particularly complex, since twice the number of participants are required in order to find statistically significant differences,” explained Professor Levy.

There is a dramatic metabolic difference between males and females, impacting both their health and their behavior. It has not yet been established whether the two sexes respond differently to exposure to the sun’s UV radiation.

“The protein p53, found in the skin, repairs damage to the DNA caused by sun exposure, but it does more than that. It signals to our bodies that winter is over, and we are out in the sun, possibly in preparation for the mating season,” explained Professor Levy.

The results may ultimately inform future studies on both human metabolism and the potential for UV-based therapies for metabolic diseases and appetite disorders.

The study is published in the prestigious journal Nature Metabolism.

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By Katherine Bucko, Earth.com Staff Writer