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/ Source: NBC News
By Maggie Fox
Two studies show disrupted sleep can be bad for your waistline
Two studies show disrupted sleep can be bad for your waistlineGetty Images

You knew getting too little sleep was bad for you, but did you know it might help pack on the pounds?

A new study suggests that people who lose as little as half an hour of sleep on a weekday have change in their metabolism that might help them gain weight and that might even put them on the road to diabetes.

Dr. Shahrad Taheri of Weill Cornell Medical College in Qatar studied 522 patients who had just been diagnosed with type-2 diabetes.

They were taking part in a different study meant to see if exercise and diet would help, but as part of the study the volunteers filled out a sleep diary.

Those who got a half hour less than the recommended eight hours a night were more likely to be obese and also had what’s known as insulin resistance — a malfunctioning of metabolism that can lead to diabetes

After a year, for every half hour under eight hours, the rate of obesity went up by 17 percent and the rate of obesity went up 39 percent, Taheri’s team told a meeting of the Endocrine Society in San Diego.

Taheri has previously found that people who get too little sleep have abnormal levels of the appetite hormone ghrelin and of leptin, another appetite regulator linked to body fat.

Another study found that teens who slept less — or who slept more than usual — ate more, and ate worse food.

This study, presented Thursday at an American Heart Association meeting, used data from 342 teenagers.

Teens slept on average just seven hours a night — less than the recommended nine hours. Those who slept an hour less or an hour more than normal ate about 200 calories more those days, ate more fat and more carbohydrates, and were more likely to eat snacks.

"According to the data from our study, it's not how long you sleep that matters. It's about day-to-day variations in how long you sleep," said Fan He, an epidemiologist at Penn State University College of Medicine, who led that study.

This article was originally published Mar. 5, 2015 at 6:32 p.m. ET.