You can estimate the number of calories burned during sleep and calculate how that fits in with a weight-loss plan, but that doesn't guarantee you'll actually lose weight while sleeping. The only way you'll drop pounds is by consistently consuming fewer calories than your body needs for energy. You can also increase the number of calories lost while you sleep by following a regular sleep schedule, getting enough sleep and maintaining lean muscle.
Your body continues to burn calories as you sleep, but the only way to lose weight is to consistently consume fewer calories than you burn.
Calories Burned During Sleep
The body continues to burn calories when you're sleeping because it needs energy to keep the brain, heart, lungs and all other vital systems working. Basal metabolic rate, or BMR, is the term used to define the number of calories required to maintain internal physiological functions while you sleep. Another common term often used synonymously with BMR — resting metabolic rate, or RMR — measures energy used at rest during any time of the day.
In one hour of sleep, most people burn approximately 0.3 calories for every pound of body weight. For example, a 150-pound person would multiply 150 by 0.3 to get 45 calories used in one hour of sleep. After eight hours of sleep, that person has burned 360 calories. To lose 1 pound of weight, you need to expend 3,500 calories more than you consume.
While the amount of food consumed must be restricted to create a calorie deficit, it's possible for a 150-pound person to lose a little more than 1/2 pound weekly by burning those 369 calories every night. The number of calories lost may be significantly more or less, depending on how much you weigh and how long you sleep.
Increase Sleeping Metabolic Rate
Muscles at rest burn three times more calories than fat, so maintaining or increasing muscle mass influences BMR. One study suggests that you may increase muscle metabolism by consuming protein before going to sleep. The researchers found that a bedtime snack of protein was properly digested and increased muscle protein synthesis during sleep, according to a study in published in the journal Medicine and Science in Sports and Exercise in August 2012.
A protein drink made from casein may support muscle synthesis better than other types of protein because it's absorbed more slowly, but more research is needed to verify its effectiveness.
Drinking any caloric beverage before sleeping increases resting energy expenditure, according to a study in the journal Nutrients in April 2015. Eating habits throughout the day may also make a difference. Consuming a moderate amount of protein at each meal stimulates 24-hour muscle protein synthesis better than if you eat most of your protein at dinner, reported a January 2014 study in the Journal of Nutrition.
Of course, the total calories consumed from all meals and snacks have to fit within your daily calorie budget. Bedtime snacks should be limited to 200 calories or less and emphasize one macronutrient such as protein, recommended the Nutrients report.
Read more: 4 Surprising Benefits of Eating at Night
Sleep Schedule and Weight Loss
While you sleep, you're also fasting, which may help with weight loss. When experts subjected lab mice to the same diet but imposed different eating cycles, the mice with an enforced fast lost more weight than the animals allowed to eat whenever they wanted. The researchers discovered that the animals began to burn fat only after a few hours of fasting, reported Cell Metabolism in June 2012. More research is needed to prove the same effect happens in people, however.
Lack of sleep is associated with weight gain due to changes in hunger hormones and metabolism. On the flip side, maintaining a regular sleep schedule and getting eight hours of sleep preserves muscle mass, which keeps BMR higher.
In a study exploring the effect of sleep loss on metabolism, two groups of adults followed a calorie-restricted diet, but each group got different amounts of sleep. Everyone lost about the same amount of weight, but the group that got less sleep — 5.5 hours each night — lost 60 percent more muscle and 55 percent less fat. By comparison, the group that slept 8.5 hours lost more fat than muscle, according to a report in the Annals of Internal Medicine in April 2010.
The researchers concluded that sufficient sleep helps maintain lean muscle, but because the study only included 10 subjects, more research is needed to verify these results.
Read more: The Effects of Sleeping 5 Hours a Night
Improving Sleep and Metabolism
You can make changes to help your body burn more calories while sleeping. Try to keep the room temperature comfortably cool because your metabolism kicks in to raise body temperature. The metabolic rate increases with a minimal drop in room temperature, from 72 degrees to 61 degrees Fahrenheit, according to a report in the European Journal of Clinical Nutrition in April 2002.
Because you'll support weight loss by getting enough sleep, avoid dietary factors that interfere with restorative sleep, such as alcohol, caffeine and big spicy meals that might cause indigestion. A good night's sleep also depends on honoring natural sleep-wake cycles. The brain secretes melatonin when it's dark, which makes you sleepy. As daylight dawns, the amount of melatonin goes down to make you more alert. You'll have a hard time falling asleep if you have lights on in your room. Blue light emitted from electronics, such as your phone, television, computer or tablet, is especially disruptive.
- Medicine and Science in Sports and Exercise: "Protein Ingestion Before Sleep Improves Post-Exercise Overnight Recovery"
- Nutrients: "The Health Impact of Nighttime Eating: Old and New Perspectives"
- Journal of Nutrition: "Dietary Protein Distribution Positively Influences 24-Hour Muscle Protein Synthesis in Healthy Adults"
- Cell Metabolism: "Time-Restricted Feeding Without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet"
- Annals of Internal Medicine: "Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity"
- European Journal of Clinical Nutrition: "Energy Metabolism in Humans at a Lowered Ambient Temperature"
- University of Rochester Medical Center: "Calorie Burn Rate Calculator"