According to a new study out of Pennsylvania State University, just four nights of poor sleep can lead to weight gain.
The findings, published in the Journal Of Lipid Research, suggest that not getting enough ZZZs changes the way the body stores fat and increases the risk of obesity.
For their research, scientists recruited 15 males in their 20s. In the first week, volunteers enjoyed 10 hours of sleep a night.
They then spent the next ten nights at the Clinical Research Centre at Penn State. During their stay at the clinic, they were put on a diet limited to a high-fat, calorie dense plat of chilli and pasta.
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While visiting, their sleep was restricted to five hours for four consecutive nights.
By taking blood samples, researchers found that the lack of sleep led to high levels of insulin – a hormone necessary in taking glucose from the bloodstream (type 2 diabetes is when the body can't efficiently use it's insulin to manage blood glucose levels).
In this case, due to the high levels of insulin, the body takes in fats and lipids quicker, leading to weight gain.
"Across a lifetime of exposure to short sleep, this could increase the risk of obesity, diabetes, or other metabolic diseases," said lead author Kelly Ness.
"The primary problem in obesity is how fat tissue functions to store fat energy," adds co-author and associate professor of nutritional sciences at Penn state, Dr Greg Shearer.
"By storing fats quickly, fat tissues appear to shift fuel utilisation away from fats and prioritise the use of sugars for fuel. Here we show evidence that sleep restriction exaggerates this process, conserving energy stores."