One in three people sleep less than seven hours each night. One in three people are obese. There might be a connection there.



Although everyone who’s overweight or obese isn’t sleep-deprived, and some people who are sleep-deprived might stay skinny, sleep definitely plays a role on body composition for most of us.



A new study shows sleep debt causes you to store more fat, even when your diet remains unchanged. It also leaves you less satisfied from your meals, which could cause you to eat more than you need.



On top of that, a second study just published shows that sleep debt isn’t just a problem for adults. It sheds more light on the impact it has on adolescents, especially girls.



I’ll touch on these recent findings below.



Not surprisingly, it's one of the three synergistic health habits I discuss in my book, The 3 Pillars of VIGOR.





Short-Term Sleep Debt, Body Fat, and Satiety



The first study looked at the impact of sleep debt during a typical workweek.



Prior to beginning the study, fifteen healthy, young men spent a week at home, getting 10 hours in bed each night.



Note: The researchers could only account for time in bed (TIB), not for actual hours slept, to run the study. That’s why I use the unusual phrase “time in bed” instead of hours slept.



Then, they checked into the sleep lab, where they got 10 hours of time in bed for another three nights. That's 10 days in a row with 10 hours in bed. You might be wondering, "How can I get in on one of these studies?! Ten hours would be amazing!"



Following their first three nights at the sleep lab, they were restricted to just five hours of time in bed for five nights in a row, similar to the lifestyle many Americans live each week. After those five nights of sleep restriction, they got two more nights of 10 hours time in bed to see if they recovered.



Rather than looking at the impact the sleep debt had on breakfast the next morning, which is what most research has already reviewed, this group wanted to look at the impact of sleep debt on dinner, the biggest meal of the day for most people.



Dinner remained the same on all nights, including the nights they got 10 hours of bedtime. So, the only difference in everything was the time in bed.



The participants blood sugar fluctuations were the same after the nights with 10 hours or five hours of sleep. But their insulin levels were higher on the days following their shortened sleep.



Without a change in blood sugar, insulin levels increased. Insulin increases fat storage, which the researchers saw based on the lab work they performed.



In essence, the simple act of restricting sleep caused the participants to store more fat. On top of that, they felt less satisfied from the meals they ate. Given the opportunity to eat more, they probably would have. And, had they eaten more, based on their insulin levels, they would have stored more energy as fat.



This explains why people can get fatter without a change in diet, or why they can’t lose weight if they try to diet while in sleep debt.



The other interesting finding was that even after the two additional nights of 10 hours of sleep, their hormone levels had still not returned to normal.



Teenagers With Too Little Sleep Are More Likely To Become Overweight Too



Another study, just published in the Journal of The American Medical Association, Pediatrics, looked at the sleep patterns and body composition of 800 adolescents. 



Not surprisingly, the less sleep they got, the more likely it was that they’d be overweight.



That shouldn't be a surprise.



What was a surprise was that those who went to sleep later, or who went to sleep at inconsistent times, were more likely to be overweight, regardless of the difference in hours they slept.



This is an important finding for parents who think the solution is a later start time for schools. That's probably not going to help.



The late or inconsistent bedtimes screw up their circadian r...