Most Americans gain at least a few pounds over the winter months, and new research suggests it’s not just because of holiday-related overeating.

A recently released study finds that winter weight gain is real, and that it might not be a lack of gym time or unhealthy diets to blame. The culprit: Lack of sunshine.

Researchers at the University of Alberta in Edmonton, Canada, report in a study published in the journal, Scientific Reports, that lower levels of sunlight exposure around the holidays — and the months that follow — affect levels of body fat.

Subcutaneous fat cells — better known as white fat cells, which are found right underneath the skin — regulate metabolism, as they store calories to be burned. But the new research indicated that lack of sunlight can throw the system out of whack, leading to obesity, diabetes, and heart disease.

Peter Light, who led the team of researchers, said the scientists were originally attempting to genetically engineer white fat cells to produce insulin when exposed to light — a possible treatment for those with Type I diabetes.

But as sunlight shone on those white fat cells, they began to shrink — an unexpected discovery that led the research team to dig a little deeper to understand why and whether the reverse — lower levels of sunlight could promote fat growth — might be true.

“When the sun’s blue light wavelengths — the light we can see with our own eye — penetrates our skin and reach the fat cells just beneath, liquid droplets reduce in size and are released out of the cell,” Light explains.

“In other words, our cells don’t store as much fat [when exposed to sunlight].”

The take-home message of these findings: New weight-loss strategies and light-based therapies may be effective in the treatment of diabetes or obesity.

Light explains that “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.”

The results of this study suggest that it is possible, and likely, that the light that regulates a person’s circadian rhythms that govern sleep might also have the same impact on the fat cells under their skin. That means getting sun exposure, and making sure to follow regular wake-sleep patterns, may help you lose weight and keep it off.

Light notes more research needs to be done and that many variables remain unknown.

“For example, we don't yet know the intensity and duration of light necessary for this pathway to be activated,” he explains.

While it’s not certain how exactly to use light treatments, there are still some steps you can take to combat winter weight gain:

• Make sure to get a little sunlight every day, even in colder winter months.
• If that’s not a possibility, try taking supplements of vitamin D, known as the “sunshine vitamin.”
• Be sure to practice healthy sleep hygiene to keep your circadian rhythms in check. Experts advise aiming to get at least seven hours of sleep each night, going to bed and waking the same time every day, avoiding food and drinks (particularly those containing alcohol or caffeine) in the hours before bedtime, and don’t use smart phones, computers, iPads right before bedtime because they emit “blue light,” which interferes with the production of the natural sleep hormone melatonin.

With obesity rising generation after generation, the findings of this study might spark the debate about what healthy sunlight exposure is and should be. It might be that with the right amount of sunlight, future generations can combat obesity.

The implication of his findings “[hold] many fascinating clues for our team and others around the world to explore,” Light says.