Lack of sunlight may cause winter weight gain, research suggests

  • Jason Lemon
  • For the AJC
10:02 a.m. Tuesday, Jan. 16, 2018 Health

We often blame our added winter pounds on the holidays. All the gatherings of family and friends combined with good food, often take the toll on our waistlines.

But if you're one of the many who laments adding a few pounds in December, it may not actually be entirely due to changes in your diet. In fact, new research suggests that a lack of sunlight may be causing some of that unwanted weight gain.

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The study, published by researchers at Canada's University of Alberta in the scientific journal Nature, reveals that blue light emitted by the sun actually causes fat cells sitting beneath the skin to shrink. In the winter months, when there is generally less sunlight in many regions and people readily cover their skin to stay warm, the cells store more fat.

"When the sun's blue light wavelengths − the light we can see with our eye - penetrate our skin and reach the fat cells just beneath, lipid droplets reduce in size and are released out of the cell. In other words, our cells don't store as much fat," Dr. Peter Light, who led the research said, according to The Independent.

In other words, the illusion of looking thinner after a day tanning at the beach may not be entirely an illusion. The sunlight we're exposed to actually has a slimming effect on our fat cells.

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However, Light also cautions against using exposure to sunlight as a means of losing weight.

"We don't yet know the intensity and duration of light necessary for this pathway to be activated," he told Global News, explaining that the findings are preliminary and more research is necessary.

Light also explained that the discovery happened by accident. The research team was attempting to engineer fat cells to create insulin to help treat type 1 diabetes. Along the way, the scientists noted how the fat cells responded to sunlight.

Cracking a joke about the findings, Light told CBC that he's "finally living up to his name."

Palm Beach Post Staff Writer
Forecasters expect a mostly sunny sky with highs in the upper 70s today. (Richard Graulich / The Palm Beach Post)

Benefits of sunlight

Many people have long turned to tanning beds during the winter month, but Light said these methods don't necessarily have the same effect as direct exposure to the sun.

"We think that that great big nuclear reactor in the sky, the sun, is what's required," he explained. "We need really intense light to actually penetrate the skin."

The sun is already known to help our bodies generate vitamin D, and now Light believes his research has shown another important benefit to sunlight exposure.

"It may help regulate your body weight and a lack of it may actually lead to extra storage of [fat] in the winter," he said.

Next steps

While Light cautioned against jumping to any rash conclusions, he is optimistic that sunlight may one day be used in the treatment of obesity.

"Maybe this mechanism contributes to setting the number of fat cells we produce in childhood — thought to stay with us into adulthood," he said.

"Obviously, there is a lot of literature out there suggesting our current generation will be more overweight than their parents and maybe this feeds into the debate about what is healthy sunshine exposure," he added.

As of now, the research is only preliminary and more work is needed to determine the full effects and benefits of sunlight on weight. At the same time, the discovery has already suggests many interesting possibilities.

"Our initial first observation certainly holds many fascinating clues for our team and others around the world to explore," Light said.