When you lounge in the sunshine, you might not only be topping up your suntan, you could be shrinking your fat too.   

Researchers have discovered that the fat cells that lie just beneath your skin react when exposed to the blue light emitted by the Sun. It turns out that the lipid droplets held within these cells shrink in size and are then released, meaning o ur cells are basically not holding onto as much fat.

“If you flip our findings around, the insufficient sunlight exposure we get eight months of the year living in a northern climate may be promoting fat storage and contribute to the typical weight gain some of us have over winter,” explains the ironically named Professor Peter Light, who led the research published in Science Advances, in a statement. (Then again, it could always be all the extra biscuits you're snaffling).

The discovery was – as is often the case – one of chance. The team were actually investigating how to bioengineer fat cells to release insulin in response to light as a potential treatment for Type-1 diabetes, but noticed that in their control sample of human fat cells, the lipid droplets were shrinking in response to the light too. After a search of the literature, they found no record of this response, and so delved into it themselves.

While this is an interesting finding, don’t expect that lying on a sunbed during the winter months will stop you from gaining all that holiday weight, as the researchers caution that this is only an initial observation. Not to mention the fact that exposing yourself to too much sunlight is bad for you in a whole host of other ways. Also, it’s not exactly going prevent the build-up of all that fat surrounding your organs.

What is interesting, however, is the connection this effect of sunlight might have with our body clock. “It's early days, but 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,” says Light.

The researchers are floating the question that maybe the exposure to sunlight that helps regulate our sleep-wake patterns – which is known to occur in our eyes – also acts in a sensory manner, in which the amount of fat a person burns depends on the season. They even suggest that this could help explain why humans are unlike many mammals in having our fat spread out all over our bodies and just below the surface of the skin.

Needless to say, this is all just conjecture at the moment, but it provides a fascinating avenue to explore.