Want to shed a few extra pounds? Here’s an idea, and it’s simple enough: try sleeping a bit more.

The link between sleep and obesity is not new — it’s been reported several times by researchers. A 2012 study found that lack of sleep can impact appetite regulation and impair glucose metabolism, while a 2011 review of studies found substantial evidence linking obesity and a lack of sleep. However, the exact nature of this link has not been thoroughly explained. A new study presents some of the most compelling evidence to date, showing that a lack of sleep encourages the body to store more fat, altering the body’s metabolism and an essential DNA function.

“Chronic sleep loss, social jet lag, and shift work—widespread in our modern 24/7 societies—are associated with an increased risk of numerous metabolic pathologies, including obesity, metabolic syndrome, and type 2 diabetes,” researchers explain in the new study. “Even minor weekly shifts in sleep timing, or as few as five consecutive nights of short sleep, have been associated with an increased risk of weight gain in healthy humans.”

Jonathan Cedernaes, a circadian researcher at Uppsala University in Sweden and lead author of the study says that sleep has an “irreplaceable” function, it’s not just to conserve energy and replenish our stamina. Yet many people tend to consider it an expendable resource — and this can have massive consequences.

Cedernaes and colleagues recruited 15 volunteers, who attended two testing sessions: once after a normal night’s sleep, and once after staying up all night. Biopsies and samples of fat, muscle tissue, and blood were also taken, and participants underwent a separate electroencephalography (EEG) and were asked to also complete sleep, food, and activity diaries as part of their screening.

The most significant change researchers note is in a gene activity called DNA methylation. The change was linked to cells increasing their tendency to absorb lipids, boosting the body’s ability to store fats. Furthermore, the participants’ muscle cells contained lower levels of structural proteins after a lack of sleep, suggesting a reduced ability to build and maintain muscles.

Lastly, scientists also report an increase in inflammation in the body after sleep deprivation, a major risk factor for type 2 diabetes, among others.

While previous studies have suggested a connection between obesity and sleep deprivation, this link was hard to separate from other lifestyle changes. Now, researchers have shown a physical mechanism that is responsible (or at the very least partially responsible) for this connection.

It should be said that the study featured a very small sample size and only analyzed a brief moment in the life of the participants. For the future, researchers call for more investigations to see what the effects of sustained sleep deprivation are on a wider segment of the population. But for now, it’s safe to say that sleep is not something you should be missing out on.

The study has been published in Science Magazine.