When your body requires more energy than your diet provides, it taps into its fat stores to offset the deficit. Consequently, you lose weight.

It’s an adjustment that just makes sense.

Here’s one that doesn’t.

When you sleep less than you should, you eat more - even though the energy increase this creates is negligible at best. Typically, you gain weight in the form of body fat.

That was proven and published years ago, and it’s been proven and published again. Twice in the last two months.

The first, found in the Feb. 7 online issue of JAMA Internal Medicine, explains why follow-up study was necessary. The prior studies were short in term, extremely sleep restrictive, and “energy intake was ascertained from a single or a few meals.”

In short, they “do not represent real life,” so the researchers at the Clinical Research Center at the University of Chicago, led by Esra Tasali, MD, and Kristen Wroblewski, MS, created one that did. They recruited 80 healthy men and women between the ages of 21 and 40 who were overweight but not obese and had ordinarily slept less than 6.5 hours per night for the last six months.

After observing the 80 individuals for two weeks, the researchers divided them into two groups. One group received sleep counseling with the goal of increasing their sleep time to 8.5 hours a night; the other didn’t.

Both groups were instructed to go about their lives as they had before. They were not given diets or workouts to follow.

Their sleeping and eating patterns were then monitored for two more weeks.

At the end of that time, the sleep counseling was deemed a moderate success. Those who received it were now sleeping 1.2 more hours per night on average (60 percent of the targeted goal) compared to the control group.

With that extra sleep, though, came an additional benefit: “a significant decrease in energy intake.” When compared to the control group, the sleep extension group consumed 270 fewer calories per day on average.

That change, according to the prediction model used in such research, creates a 26-pound weight loss over three years.

The Centers for Disease Control and Prevention’s latest figures have the rate of obesity in the U.S. at 42 percent - a 28-percent increase since 2000. A Gallup poll from 2013 has timed the average American sleeps each night at 6.8 hours - a 13-percent decrease from a time when you’d expect Americans to be seriously sleep-deprived, 1942, the first year the U.S. was fully engaged in WWII.

Taking both into account, it’s easy to see why the researchers at the University of Chicago’s Clinical Research Center feel their findings prove “the importance of improving and maintaining adequate sleep duration as a public health target for obesity prevention.”

And why the aforementioned second study hits that target’s bullseye. Performed at the Mayo Clinic and published in the April 5 issue of the Journal of the American College of Cardiology, it links a lack of shut-eye not only to an increase in calories consumed and a subsequent increase in body fat, but also to an increase in the unhealthiest type of body fat.

The belly fat deeper than the stuff that droops over your belt buckle.

In the same way a piece of real estate becomes more valuable based on location, body fat becomes more dangerous. When you carry more than the amount of abdominal visceral fat needed to protect the organs, you increase your risk of heart disease, stroke, type 2 diabetes, and Alzheimer’s disease significantly.

And in only two weeks, Mayo Clinic researchers created an 11% increase of it in healthy individuals who were not obese and between the ages of 19 and 39 simply by restricting their sleep.

After having all 12 participants sleep 9 hours a night for four nights, the researchers had six sleep 4 hours a night for two weeks while the others continued sleeping 9. In only two weeks’ time, an 11% increase in unhealthy belly fat occurred.

Something of equal concern, however, was detected after a three-day recovery period where the sleep-deprived six again slept 9 hours a night.

Even though they started eating less than the 300 extra calories they averaged during the two weeks of 4 hours of sleep and even though their overall amount of body fat began to lessen, all the added bad belly fat remained.

In a news release about the research, study leader Naima Covassin, PhD, an assistant professor of cardiovascular medicine at the Mayo Clinic, explains that because visceral fat can only be assessed through CT scans, “Measures of weight alone would be falsely reassuring in terms of the health consequences of inadequate sleep.” She also warns of the potential adverse effects of “repeated periods of inadequate sleep in terms of progressive and cumulative increases in visceral fat over several years.”