A team of researchers at the University of Alberta in Canada has uncovered an extraordinary new, previously undiscovered, fat-burning mechanism. The new study reveals fat cells just under the skin are sensitive to a specific spectrum of sunlight and shrink when exposed.

As with many wonderful scientific discoveries, this new mechanism was unearthed completely by accident while the team of researchers was investigating ways to use light as a trigger to make fat cells produce insulin.

"It was serendipitous," says Peter Light, senior author on the study. "We noticed the reaction in human tissue cells in our negative control experiments, and since there was nothing in the literature, we knew it was important to investigate further."

The mechanism seemed to be similar to the way blue light regulates our circadian rhythms, so the researchers looked more closely at the effect these light wavelengths could be having on white adipose tissue near the surface of the skin.

"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," explains Light. "In other words, our cells don't store as much fat."

The new study is presented by Light and his team with a degree of caution. These findings are new and demand a great deal of further research before something akin to a light-based treatment for obesity can be considered. The study also notes that no work has been done yet to determine an appropriate duration or intensity of light to specifically activate this mechanism, so extended bouts of lying in the sun to lose weight is not at all recommended.

Perhaps one of the more fascinating implications of the discovery is the possible evolutionary origin behind our body developing this specific metabolic pathway. During darker, winter periods it would certainly have been beneficial for our distant relatives to gain weight. As humans spread their fat all over the body, general weight gain can be useful for warmth so an endogenous pathway that detects sunlight levels and signals to either burn fat or gain weight is a pretty clever and efficient mechanism to evolve.

The research was published in the journal Scientific Reports.