It’s not because you’ve skipped that kale salad.
Credit: Stockvisual,

Winter weight gain isn’t unusual—with food-based holidays, parties, and plenty of overindulging, it’s hardly surprising when your jeans feel snug or the scale goes up a few pounds.

But there’s another surprising factor that could possibly lead to weight gain—the sun.

New Year. New Food. Healthy eating starts here, with the Cooking Light Diet.

In wintertime—especially if you live someplace where it gets really cold—you’re likely staying inside. But a new study conducted by the University of Alberta shows that might not be the best plan (and it’s not just because you’re skipping your outdoor jog!)

The study, published in the Nature journal Scientific Reports,  found that our fat cells actually shrink when exposed to blue light emitted by the sun.

Peter Light, director of the University of Alberta's Diabetes Institute and senior author of the study, told Folio, "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.”

And, explained Light,  if you flip the study’s findings around, you can deduce that insufficient sun exposure could promote fat storage and contribute to winter weight gain.

So, if you’re trying to lose weight, should you book a trip to the Caribbean ASAP? Well, yes and no. Yes, because that would be a delightful winter reprieve, and no, because scientists haven’t determined the intensity or duration of sunlight needed to activate fat burning, and they also don’t recommend using the sun as a weight loss tool.

"It's not a giant leap to suppose that the light that regulates our circadian rhythm, received through our eyes, may also have the same impact through the fat cells near our skin,” Light explained to Folio's Lesley Young.

Light also believes that because sunlight can dictate our sleep-wake patterns through our circadian rhythm, it may also be able to determine the seasons in which we store or burn fat.

If you’re someone who tends to gain weight in the winter and lose it in the summer, Light told Young, “This could be evolutionary process, supported by the fact that unlike many other mammals, our fat is spread out all over our bodies just underneath our skin.”

The bottom line? If you gain a few extra pounds in the winter, don’t beat yourself up. If you’re trying to lose some weight, don’t just rely on the sun as a miracle worker. For best results, you still need to eat healthy and get frequent exercise.