Does sleep influence the number you see on the scale? We dug into the science.

Brierley Horton, MS, RD
September 24, 2020
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A solid night of shuteye is so crucial—for our body and mind, yet most of us don't get what we truly need. Many Americans report sleeping only about 7 hours a night, and lots of us log even fewer hours, which is when it becomes unhealthy.

"Adequate sleep helps to allow your body to perform all the regulatory and maintenance functions it needs to function properly. Healthy sleep also helps set the stage for many domains of health," says Michael A. Grandner, Ph.D., M.T.R., director of the Sleep and Health Research Program at the University of Arizona College of Medicine. If you're someone who has trouble getting enough sleep, try this #1 food to eat for better sleep according to a dietitian.

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A recently published review of the research, which was authored by Grandner actually, shows that insufficient sleep can shorten your lifespan, stoke inflammation, raise your risk of diabetes and heart disease, and negatively effect your mental health.

But what about your weight? Does sleep play a role in the number the see on the scale? We dug into the science.

How sleep influences your appetite

When we fall short on sleep, research shows our ghrelin levels (the hormone that make you feel hungry) go up, and our leptin levels (the hormone that helps you to feel full) dip, explains Grandner. Also, when leptin levels rise—which appears to happen during sleep—it counter regulates ghrelin and has the potential to tamp down your hunger.

Falling short on sleep also disrupts how your body regulates insulin and glucose, as well as other substances in the body that regulate hunger and appetite.

Can sleep help or hinder your weight loss goals?

Skimping on shuteye has the potential to make losing weight that much harder. Here's why: "Not only does lack of sleep disrupt hormones that regulate hunger and appetite, it also leads to increased eating of unhealthy foods at night, decreases energy level which leads to craving energy [aka food], and even impairs brain function which makes it harder to make healthy choices," explains Grandner.

Take a look at the research on the topic and you'll see that there is a connection between sleep and body weight. Research shows that folks who consistently fall short on sleep weigh more over time than their counterparts who get adequate sleep. Other studies have found that dieters who lose even just a little bit of sleep aren't as successful at losing weight compared to dieters who log enough Zzs. For instance, one study, published in Sleep, put one group of adults on a calorie-restricted diet and told them to cut out about one hour of sleep five days a week (the other two days they could sleep as much as they wanted). Another group went on the same calorie-restricted diet. The findings? Compared to the dieters who didn't limit their sleep, the sleep "deprived" group lost less body fat. Both groups, however, lost about the same amount of total body weight.

All of this said, there are some studies that suggest the impact of sleep on weight isn't all that significant (statistically speaking, too). And then there's research that found men to be more likely than women to pack on the extra pounds when their sleep is lacking.

So, how many hours of sleep should you aim for?

Is there a magic number you need to get to best support your diet and meet your weight loss goals? "Most of the evidence shows that most adults need at least 7 hours of sleep on a typical night, and probably not more than 9 hours," advises Grandner. There is some evidence that too much sleep can have a similar effect on your weight as too little sleep. "And this recommendation is echoed by most major medical and scientific authorities, based on over 50 years of scientific data."