A new study published in the Journal of Investigative Dermatology on May 22 by researchers at Seoul National University Hospital in South Korea suggests that sunbathing may have the benefit of allowing people to "eat light without getting fat." Their research indicates that exposure to ultraviolet light can increase appetite while preventing weight gain. These findings could offer new hope for preventing and treating obesity and metabolic disorders.
Sunlight contains ultraviolet rays, which can lead to harmful effects such as sunburn, photoaging, and skin cancer, but it is also involved in synthesizing vitamin D.
Previously, the team found that ultraviolet light exposure on the skin does not directly reach subcutaneous fat but can regulate its metabolism. The latest study reveals that ultraviolet light exposure limited weight gain in obese mice.
Leptin is a natural appetite suppressant secreted by the body's fat tissue. Researchers observed that mice exposed to continuous ultraviolet radiation exhibited reduced leptin levels and increased appetite when fed a normal or high-fat diet, yet their weight did not increase.
They found that ultraviolet exposure increased adrenaline levels, decreased leptin levels, and induced browning of subcutaneous fat, thereby increasing energy expenditure. Due to enhanced appetite and increased energy intake, the energy was converted into heat and burned off before being stored in subcutaneous fat, thus preventing weight gain.
