Get ready to learn something shocking: if you’re trying to shape up or slim down, clocking the right amount of slumber is even more important than blocking out time for exercise and stocking your plate with healthy grub.
Yep. MORE important.
All these years the mantra has been “eat right and exercise,” “eat right and exercise,” “eat right and exercise,” but there’s a significant body of research showing a solid connection between sleep and weight gain. That is, if you’re not getting enough (7-9 hours), you’re paving the path to extra pounds. And 40% of adults in the US are not, according to a Gallup poll (1).
Lack of sleep can lead to all sorts of negative health impacts, but if your weight is your primary focus right now, here are 7 reasons to go to bed earlier, sleep later, and do whatever you can to bank enough shuteye.
#1 Lack of sleep makes you feel hungrier.
Two hormones go hand-in-hand in your body to control feelings of hunger and fullness: ghrelin stimulates your appetite and leptin tells your brain when you’ve had enough to eat. Without enough sleep (even just one night), ghrelin levels leap and leptin levels lag – which means that not only will you feel hungrier, you’ll also likely eat bigger portions because it’ll take more to feel full (2).
#2 Sleep loss makes you crave junk food.
A study conducted at the University of Chicago found short-term sleep loss makes you crave high-calorie, high-carb foods (3). "We don't yet know why food choice would shift," said Eve Van Cauter, Ph.D., professor of medicine at the University of Chicago. "Since the brain is fueled by glucose, we suspect it seeks simple carbohydrates when distressed by lack of sleep." Along the same lines, another study found a lack of sleep makes food smells like potato chips and cinnamon rolls more enticing (4). It’s a double whammy of diet destruction (quadruple if you count feeling hungrier and eating bigger portions!).
#3 Your insulin sensitivity will be a similar degree as if you’ve been on a high-fat diet.
You read that right. According to a study out of Cedars-Sinai Medical Center in Los Angeles, one night of bad sleep lowers our body’s sensitivity to insulin in a similar degree as 6 months on a high-fat diet (5). A decrease in sensitivity to insulin or “insulin resistance” makes your body unable to keep blood sugar stable, which can eventually lead to Type 2 diabetes. (Note: The study was conducted on dogs, but it’s still very telling.)
#4 Sleep loss makes your body more likely to store fat.
Similar to the study above on insulin sensitivity, another study published in the Annals of Internal Medicine found that sleep restriction created insulin resistance in the cells in your body that store fat, messing with your metabolism and making your body more likely to pack on the pounds (6).
#5 Sleep loss slows down your metabolism.
“Not only do you have more energy to take on the day after a good night’s sleep, but your body also torches calories, even when you’re not working out,” writes Julia Merz for Women’s Health Magazine (7). “A study from the American Journal of Clinical Nutrition found that normal sleepers' resting energy expenditure—the amount of calories burned when you’re not moving—was five percent higher than their tired counterparts. They also burned 20 percent more calories after a meal versus sleep-deprived people.”
#6 Sleep loss is a muscle saboteur.
We all know muscle is the enemy of fat—but did you know sleep loss is the enemy of muscle? “Scientists from Brazil found that sleep debt decreases protein synthesis (your body’s ability to make muscle), causes muscle loss, and can lead to a higher incidence of injuries,” writes Adam Bornstein for Shape.com (8). “If you're someone who doesn't particularly enjoy exercise, not prioritizing sleep is like getting a physical exam with your father-in-law as the investigating physician: It will make something you don’t particularly enjoy almost unbearable. When you’re suffering from sleep debt, everything you do feels more challenging, specifically your workouts.”
#7 Chronic sleep loss can lead to obesity.
As noted above, just one night of bad sleep can make you hungrier and apt to eat more. Not only can short-term sleep loss lead to increased caloric consumption, but multiple studies have suggested a link between chronic sleep deprivation and increased obesity risk over time. According to the CDC, people that get less than 7 hours of sleep a night are 24% more likely to be obese (9). And, the American Sleep Association says 3–5% of the overall proportion of obesity in adults could be attributable to short sleep (10).
Before you start sleeping every chance you get, be aware that too much sleep has been linked to weight gain, too. For example, one Canadian study investigated the lifestyle habits of 276 people over six years, and found that those who slept more than 9 hours per night actually gained more weight than “normal” sleepers over a six year period – and they were 21% more likely than normal sleepers to become obese (11).
So, how much sleep should you get? There’s no hard number that applies to every single person, but a good rule of thumb is to get 7-9 hours of sleep per night. If you have a night or two where work or life demands beat out the need for sleep, try to make it up with extra sleep in the ensuing days.
All these years we’ve been treating sleep like a luxury, but it could make all the difference in your efforts to stay in shape – and ultimately mean more than any other health commitment you make.
- Gallup, Inc. “In U.S., 40% Get Less Than Recommended Amount of Sleep.” Gallup.com, 19 Dec. 2013, news.gallup.com/poll/166553/less-recommended-amount-sleep.aspx.
- Schmid, Sebastian M., et al. “A Single Night of Sleep Deprivation Increases Ghrelin Levels and Feelings of Hunger in Normal-Weight Healthy Men.” Journal of Sleep Research, vol. 17, no. 3, 2008, pp. 331–334., doi:10.1111/j.1365-2869.2008.00662.x.
- University Of Chicago Medical Center. "Sleep Loss Boosts Appetite, May Encourage Weight Gain." ScienceDaily. ScienceDaily, 7 December 2004. <www.sciencedaily.com/releases/2004/12/041206210355.htm>.
- Hamers, Laurel. “Food Odors Are More Enticing to Sleep-Deprived Brains.” Science News, 20 Apr. 2017, www.sciencenews.org/article/food-odors-are-more-enticing-sleep-deprived-brains.
- Obesity Society. "Insulin sensitivity: One night of poor sleep could equal six months on a high-fat diet, study in dogs suggests." ScienceDaily. ScienceDaily, 4 November 2015. <www.sciencedaily.com/releases/2015/11/151104134039.htm>.
- Broussard, Josiane L., et al. “Impaired Insulin Signaling in Human Adipocytes After Experimental Sleep Restriction.” Annals of Internal Medicine, vol. 157, no. 8, 2012, p. 549., doi:10.7326/0003-4819-157-8-201210160-00005.
- “6 Ways Sleep Can Help You Lose Weight.” Women's Health, 21 Apr. 2017, www.womenshealthmag.com/weight-loss/sleep-weight-loss.
- Bornstein, Adam. “Why Sleep Is More Important Than We Ever Thought.” Shape Magazine, Shape Magazine, 28 Nov. 2017, www.shape.com/lifestyle/mind-and-body/why-sleep-no-1-most-important-thing-better-body.
- “Sleep and Sleep Disorders.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 2 May 2017, www.cdc.gov/sleep/data_statistic…
- “Sleep Statistics - Research & Treatments.” American Sleep Assoc, www.sleepassociation.org/sleep/sleep-statistics/.
- Chaput, Jean-Philippe, et al. “The Association Between Sleep Duration and Weight Gain in Adults: A 6-Year Prospective Study from the Quebec Family Study.” Sleep, vol. 31, no. 4, 2008, pp. 517–523., doi:10.1093/sleep/31.4.517.
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