Sunlight May Trigger Hunger Hormone In Men
Researchers have found that sunlight causes the release of ghrelin into the bloodstream in men, stimulating appetite and increasing food intake.
We are all quite familiar with the dangers and benefits of the sun to our physical and mental health.
A good dose of sunlight on our skin (protected by sunscreen) offers an increase in vitamin D which reduces inflammation, modulates cell growth and strengthens our bones. Interestingly, a recent study demonstrated that Vit-D supplements have little benefit, so the sun is, in fact, the best source of this essential vitamin.
The sun is also credited with an improved mood for a “sunny disposition,” boosting our serotonin levels and warding off Seasonal Affective Disorder (SAD). Other key benefits offered are better sleep, help with anxiety and depression, and a possible link to improved low blood pressure.
Sun and UVB exposure have a complex relationship with our health. UVB rays are associated with sunburn, darkening and thickening of the skin, severe melanoma, actinic or solar keratoses, premature aging and cataracts.
Although we understand that sexual dimorphism explains the metabolic difference in the health and behaviors of the two sexes, little is known about the responses of males or females to environmental cues such as UV exposure.
A new study probing this dilemma, conducted at Tel Aviv University and published in the journal Natural metabolismindicated that UVB can make men, but not women, hungrier.
They found that sunlight causes the gut hormone, ghrelin, to be released into the bloodstream in men. Ghrelin is also known as the hunger hormone. It stimulates appetite, increases food intake and promotes fat storage.
Dr. Carmit Levy, associate professor in the Department of Human Molecular Genetics and Biochemistry, led the research. The study showed that the skin had a major influence on energy levels, with its results suggesting “therapeutic opportunities for gender-based treatments of endocrine diseases”.
The study analyzed the nutritional data of around 3,000 people over a year and found that men ate around 300 calories more per day than women. Further examination exposing both men and women to 25 minutes of midday sun supported the theory.
Additional experiments in mice also revealed that when males were exposed to UVB, they ate more, were motivated to seek out more food, and indeed had increased levels of ghrelin in their blood. This is not the case for female mice.
Dr. Mir Ali, a bariatric surgeon and medical director of a weight loss surgery center in California, who was not involved in the study, said Medical News Today“Much more research is needed to understand how we can use this information to help someone achieve and maintain a healthy weight.”
Although the study does not prove that UVB exposure will cause weight gain in men, it does offer some insight into the health benefits: one of many being that ghrelin also has anti-inflammatory effects, which may be linked to a reduction in cardiovascular risk.