Restricting sleep for just four days alters how the body metabolizes fats and changes how satisfying meals seem, according to a new study with 15 healthy men.

When we don’t get enough sleep, we want to eat more than we need, and store it as excess energy, says Orfeu Buxton, professor of biobehavioral health at Penn State.

“While this was a good mechanism in evolutionary terms, to store energy for tough times, it’s not so good in today’s developed world where we are relatively inactive and calorie-dense foods are easy to come by cheaply and without physical effort.”

In the new study, researchers show that higher insulin levels after an evening meal result in the faster clearance of lipids (fats), which can then lead to weight gain.

Fifteen participants, all healthy men in their 20s, spent 10 nights living in a suite in the Clinical Research Center at Penn State after a week of getting 10 hours of sleep each night at home.

During those nights in the lab, participants ate a high-fat, calorie-dense meal of chili and pasta, then slept no more than five hours each night for four consecutive nights.

“Most of the participants reported they felt less satisfied after eating the same meal while sleep-deprived, than when they had eaten it well-rested,” says Kelly Ness, a postdoctoral fellow at the University of Washington who ran the study when she was a graduate student at Penn State.

During the test meals, researchers took blood samples from participants and found that sleep restriction led to higher insulin levels, resulting in a faster clearance of lipids from the blood. “Across a lifetime of exposure to short sleep, this could increase the risk of obesity, diabetes, or other metabolic diseases,” Ness says.

The study concluded with participants sleeping 10 hours on two consecutive nights, simulating a weekend of catch-up sleep. Although participants’ metabolic processing of fat from food was slightly better after a night of recovery sleep, they didn’t recover to the baseline healthy levels after the second night; although their weights did return to baseline levels.

This suggests complex metabolic shifts occur after periods of restricted sleep and explains how sleep deprivation links to weight gain, the researchers say.

“The primary problem in obesity is how fat tissue functions to store fat energy,” says Greg Shearer, associate professor of nutritional sciences at Penn State. “By storing fats quickly, fat tissues appear to shift fuel utilization away from fats and prioritize the use of sugars for fuel. Here we show evidence that sleep restriction exaggerates this process, conserving energy stores.”

The findings have particular relevance for public health and contribute to the growing body of evidence indicating that regular, healthy sleep habits are an important lifestyle choice for well-being, the researchers say.

The paper appears in the Journal of Lipid Research. Penn State’s Clinical and Translational Sciences Institute and the Huck Institutes of the Life Sciences funded the work.

Source: Penn State

Original Study DOI: 10.1194/jlr.P094375