Too little sleep won't make you fat: study

Of course it won't.

"Skimping on sleep, is unhealthy, but it doesn't make people fat, according to a new study.

'We hoped we were going to find good evidence for that,' Dr. Diane S. Lauderdale told Reuters Health, 'because it was such an interesting, intriguing, novel idea, with some reasons to think biologically it made sense. But we found nothing.'

Chronic sleep deprivation is thought to be a risk factor for weight gain. While several studies have linked higher body mass index (BMI) to shorter nightly sleep, most have been cross-sectional, meaning they looked only at a single point in time -- making it hard to prove whether sleeping too little leads to weight gain or vice versa, Lauderdale and her colleagues explain in the American Journal of Epidemiology.

Also, they say, most studies have relied on people's own estimations of how much they sleep at night, which are notoriously inaccurate.

To address this problem, Lauderdale, of the University of Chicago, and colleagues had people wear a wristwatch-like movement-tracking device called an actigraph, which can measure sleep duration as well as sleep fragmentation, or how often a person wakes up during the night.

They looked at 612 people participating in a long-running study of heart disease risk, all of whom were in their 40s.

While shorter sleep duration was indeed associated with higher BMI, as was more fragmented sleep, adjusting for ethnicity and socioeconomic status weakened the relationship.

And people who slept less at the study's outset were no more likely to gain weight during the five-year follow-up period."

There is one thing and only one thing that makes any creature, including humans, fat - more Calories in than out.

Period. End.