Nature’s fat burner! Research shows how sunbathing melts body fat and reduces your appetite

Regular sunbathing can act as a natural fat burner, a study suggests.

Conventional wisdom says that people are less hungry on sunny, warm days, and now researchers have shown why.

UV radiation reduces the amount of hunger hormones in the body, which increases appetite, but a simultaneous increase in the stress hormone norepinephrine increases the breakdown of fat, preventing weight gain.

It also causes white fat, which stores energy, to be converted into brown fat, which burns energy, according to a new study in mice.

The researchers behind the study were so encouraged by their findings that they believe there could be a way to harness the benefits of UV radiation in a way that doesn’t increase cancer risk to treat obesity.

Still, this isn’t an endorsement to race to the tanning bed or lie out in the sun because of the high risk of skin cancer, including potentially fatal melanoma.

While the study shows promise for UV therapies to treat obesity, researchers say this should not lead to people sitting in the sun or lying in tanning beds without adequate protection, which increases the risk of skin cancer.

Dermatologists at Seoul National University Hospital in South Korea found that mice consistently exposed to UV radiation for 12 weeks, regardless of whether they were fed a normal diet or a high-fat diet, did not gain weight.

UV radiation caused an increase in levels of the neurotransmitter norepinephrine, which plays a crucial role in the body’s fight-or-flight response. Norepinephrine also helps regulate blood sugar levels.

Levels of the hormone leptin increased, which can lead to increased hunger because the body interprets it as a signal that the body does not have enough energy in the form of stored fat.

But instead of seeing the animals gain weight, researchers found that when exposed to UV light, an increased release of norepinephrine prompted the body to break down fat stores for energy, burning more calories without increased physical activity.

UV light also caused fatty tissue to be converted into brown fat, which burns energy to produce heat in the body.

Most of our body fat is white fat, which stores energy that the body uses to fuel basic metabolic processes and tough workouts. Obese people have an accumulation of white fat.

Brown fat, meanwhile, produces heat in the body by burning energy stores. The process begins when the body becomes cold to regulate body temperature.

Although the mice consumed more calories as their appetite increased, the body converted them into heat by converting white fat into brown fat before it could be stored under the skin, preventing weight gain.

The above graph shows changes in body weight in mice fed a normal diet. The red line represents the mice that were exposed to UV light, while the gray light represents mice that were not. Body weight was lower among those exposed to UV light

The graph shows changes in body weight in mice fed a high-fat diet. The red line represents the mice exposed to UV light on this diet, compared to mice not exposed to UV light, shown by the black line

Dr. Jin Ho Chung, lead researcher and dermatologist at Seoul National University Hospital, said: This study elucidates the mechanism by which UV exposure can increase appetite while inhibiting weight gain.

‘Specifically, the fact that UV radiation reduces leptin levels and increases norepinephrine, thereby promoting browning of subcutaneous fat and increasing energy expenditure, provides a groundbreaking clue for the development of obesity treatment strategies.’

Their discovery could pave the way for treatments that harness the benefits of UV exposure to reduce weight gain, control blood sugar levels and convert white fat into healthier brown fat.

He added: ‘This study shows that UV exposure not only affects the skin, but also plays a major role in our body’s energy metabolism and homeostasis processes.’

This does not mean that people should sit in the sun for hours without sunscreen, or use a tanning bed.

UV radiation is known to damage DNA in cells, which can accumulate over time, causing cells to grow uncontrollably. This is a typical cause of cancer.

Dr. Dong Hun Lee, co-author of the study, said: ‘Since UV exposure can accelerate skin aging and promote skin cancer, it is advisable to minimize UV ​​exposure and protect the skin with sunscreen.

‘Our research team therefore plans to conduct follow-up studies to develop new strategies that can mimic the effects of UV radiation on obesity and metabolic regulation.’

Their research was published in the Journal of Investigative Dermatology.