The Weird Factor That’s Making You Gain Weight

Korin Miller
·Writer
Photo: Getty Images
Photo: Getty Images

You know that sleep is important for your overall health, and you probably do what you can to make sure you’re getting enough on a regular basis. But life and late-night TV have a funny way of interfering with your ability to catch z’s. Now here’s extra motivation for hitting the hay early: It could help you keep your weight in check.

According to a new study published in PLOS One, adults who have poor sleep habits are more likely to be overweight and obese, and they have worse metabolic health than those who regularly get enough shut-eye. For the study, researchers had 1,615 adults in the U.K. report on how long they slept and what they ate for three to four days. They also had blood samples drawn and had their weight, waist circumference, and blood pressure recorded.

Here’s what the researchers found: People who slept about six hours a night had a waist circumference that was three centimeters larger than those who got nine hours of sleep a night. Those who slept even less than six hours a night also had a larger waist circumference than their more well-rested peers. (According to the National Sleep Foundation, adults over the age of 18 need a minimum of seven hours of sleep a night.)

Shorter sleep was also linked to reduced levels of HDL cholesterol (aka “good” cholesterol) in the study participants’s blood. HDL cholesterol helps remove “bad” fat from the body and helps protect against serious health conditions like heart disease — and with lowered levels, people may be at a greater risk for health problems.

The study didn’t find that people who had less sleep actually ate an unhealthy diet, which the researchers say surprised them. (However, other research has found a link between lack of sleep and poor eating habits.) Ultimately, the researchers concluded that lack of sleep could cause people to gain weight, which could lead to a slew of health problems like type 2 diabetes and heart disease.

The fact that poor sleepers gained weight despite eating healthy diets is confusing, but study co-author Gregory Potter, PhD, of the University of Leeds, tells Yahoo Beauty that it may also be down to time: “The longer people are awake, the more time there is to eat.”

Beth Warren, RDN, founder of Beth Warren Nutrition and the author of Living a Real Life With Real Food, tells Yahoo Beauty that hormones may be a factor too. Without enough sleep, your body produces more of the stress hormone cortisol, she explains. “This is not a fat-burning hormone,” she says. “Instead, it causes your body to be in storage mode to conserve energy contributing to weight gain over time.” Lack of sleep has also been linked to an increased craving for carbohydrates during the day and a desire to eat more calories at night, which can cause weight gain, even if your overall diet is healthy, she says.

Lack of sleep can also result in bodily inflammation, which can cause you to gain weight. When you’re asleep, your body and mind rest and recover. But when you cut that recovery short, you may not have time to decrease the inflammation in your body, Scott Keatley, RD, of Keatley Medical Nutrition Therapy, tells Yahoo Beauty. “This can be seen in the significant elevation of C-reactive protein, a marker for inflammation, in those who did not get enough sleep,” he says. “There is an increasing body of evidence which shows that chronic inflammation causes and advances many common disease including obesity and diabetes.”

It really is as simple as shutting down earlier, Potter says. He recommends doing something relaxing before bed (like reading a book) and minimizing activities that can disrupt your sleep like having coffee and being exposed to artificial light from devices like mobile phones and computers. Trying to go to bed at a consistent time each day and sleeping in a cool, dark room can help too, he says. Of course, you can’t always get seven or more hours of sleep a night, but if you get that regularly, your waistline — and your overall health — will thank you.

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