ISLAMABAD: Despite our best efforts to remain thin, it seems that during the holiday season, we put on a lot of weight. Why is that? A new study has a surprising answer.
 How much sunlight we get may influence how much weight we lose, suggests new research.

Plenty of us are familiar with the holiday weight phenomenon. But while it is true that during the holidays we're more exposed to delicious food than the rest of the year, some studies have shown that in winter, we continue to pack on the pounds despite conscious efforts to lose them. Why?

A new study — by researchers at the University of Alberta in Edmonton, Canada — reveals an unexpected culprit for winter weight gain: the absence of sunlight.

The researchers, who were led by the auspiciously named Peter Light — from the Alberta Diabetes Institute — examined the effect of sunlight on subcutaneous fat cells, or white fat cells that can be found right beneath our skin.

The results of their investigation make this a breakthrough study, and it was recently published in the journal Scientific Reports.

How sunlight 'burns' fat
Light and team examined the so-called subcutaneous white adipose tissue (scWAT), which, as the authors explain, is the "major fat depot in humans and a central player in regulating whole body metabolism."

White fat is known as the "bad" type of fat, because it stores calories that are ideally burned for energy.

If dysfunctional, this type of fat can lead to cardiometabolic disorders such as obesity, diabetes, and heart disease.

So, in an attempt to help people with type 1 diabetes, Light and colleagues were working on a way to genetically engineer these white fat cells to produce insulin when exposed to light.

Accidentally, they discovered that scWAT cells tend to shrink under the effect of the sun's so-called blue light — that is, the visible type of light that boosts attention and mood during the day.

To further test their discovery, the scientists took samples of scWAT from patients undergoing weight loss surgery and examined the effect of the sun's blue light on the fat cells.

This is what they found:
"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."