The number of calories you burn while sleeping depends on several factors. These include your body composition, metabolism, daily activities, and how well you sleep, among others.

The body is always using energy, even when you’re at rest. It burns calories to keep up essential functions, like breathing and circulating blood.

Estimating exactly how many calories the body burns at different times can be challenging, but you may be able to estimate calorie burn during sleep.

It can be challenging to determine exactly how many calories you burn while you’re asleep. However, calculating your basal metabolic rate (BMR) might give you an approximation of the calories your body burns at rest.

Metabolism is a process by which the body converts food into energy for use in daily activities. Even processes like breathing, circulating blood, and keeping your organs running burn calories.

Your BMR represents an estimate of the number of calories you burn a day at rest, or while you’re sedentary. This includes sleeping.

Calculating your BMR

A commonly used equation for calculating BMR, called the Harris-Benedict equation, factors in your sex assigned at birth, weight, and age, using inches for height and pounds for weight:

  • 66 + (6.2 x weight [lbs]) + (12.7 x height [in]) – (6.76 x age) = BMR for males
  • 655.1 + (4.35 x weight) + (4.7 x height) – (4.7 x age) = BMR for females

For example, the following equation shows the estimated BMR of a 35-year-old male who weighs 175 pounds and is 5 feet 11 inches tall:

  • 66 + (6.2 x 175) + (12.7 x 71) – (6.76 x 35) = 1,816 calories

The following shows the estimated BMR of a 35-year-old female who weighs 135 pounds and is 5 feet, 5 inches tall:

  • 655.1 + (4.35 x 135) + (4.7 x 65) – (4.7 x 35) = 1,383 calories

Remember that this equation estimates your BMR for everything your body does at rest, not just sleeping.

Also, this equation isn’t the best estimating method for everyone. Researchers note that the Harris-Benedict equation, like some other equations, isn’t appropriate for people with obesity because the equation was originally developed using a small group of people without obesity.

For people with higher body weights, the Mifflin-St. Jeor equation might be more accurate.

These are the Mifflin-St. Jeor equations for males and females, using kilograms for weight and centimeters for height:

  • (10 x weight [kg]) + (6.25 x height [cm]) – (5 x age [years]) – 161 = BMR for females
  • (10 x weight) + (6.25 x height) – (5 x age) + 5 = BMR for males

To convert your weight in lb to kg, multiply your weight by 0.453. To convert your weight in inches to cm, multiply your height by 2.54.

Many factors, including your lifestyle habits and health history, can affect how many calories your body burns while you sleep.

How much sleep you get

Getting enough high quality sleep may help your body burn more calories and maintain a moderate weight. Reduced sleep can contribute to increased appetite, weight gain, and a higher fat mass.

In general, bodies that have more fat burn fewer calories than bodies with more muscle mass.

Eating late

Though more research is necessary, a 2022 research review suggests that eating late in the day or at night — when your metabolism slows down — may increase the risk of obesity over time.

If you need to eat closer to your bedtime, it may help to focus on nutrient-dense foods that support your health. Foods higher in added sugars, salt, or saturated fats may make it harder to maintain muscle mass, which is better for burning calories than fat mass.

Having more muscle mass

Having more muscle mass in general helps you burn more calories. Regular physical activity is an essential part of a health-promoting lifestyle, and it may help to include resistance training in your routine to build and maintain muscle and help your body burn more calories.

Having certain health conditions

Certain medical conditions, like hypothyroidism, may slow your metabolism. This means you’ll experience less calorie burn at all hours and may gain weight or have a harder time losing it.

Your doctor can perform simple tests, like a blood test, to rule out certain conditions. Then, they can work with you to manage your condition and weight.

If you want to increase the amount of calories your body burns at rest, you could try a few strategies:

If you need help creating an activity plan or eating plan to support your health goals, healthcare professionals like personal trainers and registered dietitians can be good additions to your care team.

If you’re still finding it challenging to meet your health goals, a doctor may also be able to recommend additional strategies or treatments for underlying health conditions.

It’s not always possible to determine exactly how many calories your body burns at different times, including while you’re sleeping. You may be able to estimate your BMR with formulas like the Harris-Benedict equation or the Mifflin-St. Jeor equation.

If you want to boost your metabolism while you sleep, eating a balanced diet and maintaining or increasing your muscle mass may help.