Sleep and Weight Gain

Learn how simply getting a good night’s sleep could be the best way to help you control your weight and keep it under control.

By Andrea Pisani Babich

Jun 15th, 2023

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You know you are not alone in your battle to lose those extra holiday pounds when every other TV commercial hawks another trendy diet, piece of exercise equipment, or meal plan that will finally help you lose weight and keep it off. But before you go shelling out your hard-earned money for a miracle diet tool, consider these findings from a number of studies on weight loss/gain and sleep:

Sufficient, deep, restorative sleep may be the most important part of your daily regimen to help you lose weight and keep it off. That’s right. You can lose weight or at least limit weight gain by simply sleeping.

The Sleep Doctor agrees. According to Michael Breus, a sleep specialist and author of  The Sleep Doctor’s Diet Plan: Lose Weight through Better Sleep, “Sleep is probably the most important thing a person can do if they’re ready to start a diet and lose weight.”

Think you can muscle through the fatigue and simply eat less and exercise more while averaging only five or six hours of sleep a night? Or that those additional waking hours will burn even more calories and help you lose weight? Think again.

It’s recommended that adults sleep seven to nine hours every night. Your normal five- or six-hour nights can amount to a serious sleep deficit, one that could be keeping you from achieving your ideal weight. Studies show that it doesn’t take a very large sleep deficit to result in significant weight gain. Here’s some data to back it up:

  • A study presented at the annual meeting of the Endocrine Society in 2015 concludes that “as little as 30 minutes a day of sleep debt can have significant effects on obesity and insulin resistance,” according to the study’s lead author, Professor Shahrad Taheri, MBBS, Ph.D., professor of medicine at Weill Cornell Medical College in Qatar.
  • Dr. Eve Van Cauter, director of the Sleep, Metabolism, and Health Center at the University of Chicago, and her colleagues found that just one week of sleeping about five hours per night led participants to gain an average of two pounds. Yeah, you read that right: two pounds of additional weight gain in one week. Van Cauter says there’s “no doubt that insufficient sleep promotes hunger and appetite, which can cause excessive food intake resulting in weight gain.”
  • A recent study suggests that sleep deprivation triggers the brain to crave rich, sweet, and fatty foods. As if that weren’t enough to undermine your best-laid plans for healthy eating, research has also shown that inadequate sleep alters the hormone levels that control appetite making you feel like eating more than you need to.

Why Does Sleep Deprivation Affect Weight?

Let’s look at the physiological effects of sleep deprivation and how they relate to weight loss and weight gain.

1. Hormonal changes. 

The hormonal effects of sleep deprivation tell your brain to eat more. Studies show that people who don’t sleep enough have decreased levels of the appetite-suppressing hormone leptin and increased levels of ghrelin, a hormone that tells your brain you’ve had enough. These unhealthy hormone levels lead people to eat more than they need to and, consequently, gain weight.

2. Overeating.

It’s not just hormonal changes that lead people to eat more than they should. While it’s true that sleeping less means you need to consume more fuel to stay awake, apparently, it’s hard to know how much more. As a result, we often consume more than is necessary to fuel the additional energy output of staying awake. According to a 2013 study, sleep-deprived participants consumed about 300 calories beyond what they needed to function while awake. Those 300 extra calories get stored away as excess fat.

3. Sleepy brain syndrome.

The amount of food that we eat when we’re tired isn’t the only thing that leads to weight gain. It’s the kind of food we reach for when we are sleep deprived that results in excess pounds. Kenneth Wright of the sleep and chronobiology laboratory at the University of Colorado in Boulder states, “When people are sleepy, they make poor food choices and are more likely to eat more than they need.” Research has shown that study participants consumed more carbohydrates when they were sleep deprived for five days and gained a shocking two pounds during that part of the study. When they got enough sleep, they reduced their consumption of carbs and fats.

Turns out, there’s a reason why a sleepy brain makes bad food choices. Fatigue hampers activity in your brain’s decision-making and impulse control center, the frontal lobe. Furthermore, your brain’s reward center is on high alert when it is stressed by sleep deprivation and is searching for some comfort. Studies indicate that we tend to reach for feel-good foods that are high in fat and carbohydrates when we are over-fatigued. And all that is bad news for your physique and your health.

4. Impaired glucose tolerance.

Impaired what? Impaired glucose tolerance is just a fancy way of saying your body is not efficiently using your blood sugar to fuel its activity. Sleep deprivation makes it hard for your body to process blood sugar causing it to build up in the blood. One study found a 30% reduction in insulin sensitivity (or glucose tolerance) in participants who slept 4.5 hours each of four nights in a row. The result is fatigue and hunger, which leads to eating more food. And since your body is not processing glucose and calories efficiently, they get stored away as fat.

5. Enhanced gym resistance.

That’s a fancy way of saying you don’t want to exercise when you’re tired. ‘Nuff said.

6. Cortisol spike.

Studies on sleep-deprived participants have shown that levels of cortisol were elevated in the evening and decreased six times slower than in people who sleep sufficiently. Why is that bad for your weight? A spike in cortisol, a stress hormone, signals to your brain to conserve energy to fuel your wakefulness. The result? Your body burns calories more reluctantly leading to weight gain.

Furthermore, since cortisol heightens alertness, elevated levels in the evening lead to further deterioration of your sleep, starting a cycle of more sleep deprivation that leads to subsequent low quality, insufficient sleep resulting in all of the above triggers for weight gain.

And you thought the only thing that happened when you didn’t sleep enough was you woke with puffy eyes and felt cranky all day. Makes you think twice about staying up to watch another episode of Orange Is the New Black.

How Much Sleep Do You Need?

The National Sleep Foundation recommends the following amounts of sleep for each age group:

Age Sleep Recommendation May Be Appropriate Not Recommended
School-aged Children 9 to 11 hours 7 to 8 hours

12 hours

Less than 7 hours

More than 12 hours

Teenagers 8 to 10 hours 7 hours

11 hours

Less than 7 hours

More than 11 hours

Young Adults 7 to 9 hours 6 hours

10 to 11 hours

Less than 6 hours

More than 11 hours

Adults 7 to 9 hours 6 hours

10 hours

Less than 6 hours

More than 10 hours

Older Adults 7 to 8 hours 5 to 6 hours

9 hours

Less than 5 hours

More than 9 hours

To confirm that these suggestions work for you, Eve Van Cauter of the University of Chicago recommends this test: The next time you go on vacation, go to bed at your usual time but wake at your leisure without an alarm. (By the way, if you planned on setting an alarm to get you up in the morning, you need to review the definition of “vacation.”)

After a few days, record the number of hours you have been sleeping. According to Van Cauter, that should be your sleep goal when you return from vacation, plus or minus 15 minutes or so.

How to Sleep Well Every Night

That’s all well and good, but how can you get the recommended amount of sleep?

Once you determine how much sleep you need, count backward from the time you need to wake up to start your day. That’s your bedtime. Schedule that time just like any other appointment and stick to it. Consistent sleep and wake times will allow you to work with your body’s natural rhythms to get the best night’s sleep possible. Need more help? See our tips for better sleep to get you back on a healthy sleep schedule.

Adding a good night’s sleep to your arsenal of weight loss tools could be the missing piece that makes this year the year you finally get in the best shape of your life.