Do you burn calories while you sleep? Yes — the honest maths
Yes, you burn calories all night long. Your body's resting burn runs every hour of the day, so sleep still counts toward your Burnie deficit. Here is the simple maths behind the night burn.
It is 11 pm. You are lying in bed. You did not eat dinner. A small worry comes: "If I sleep now, am I even burning anything?" Good news. Yes, you are. Your body never stops working, not even for one minute of the night.
Your body switches off when you sleep, so you barely burn anything.
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Your body has no off switch. While you sleep, your heart still pumps. Your lungs still breathe. Your brain stays busy. Your kidneys keep cleaning your blood. All of this takes energy. Scientists even have a name for it: sleeping metabolic rate. They measure it in a chamber while you sleep, and compare it to your basal metabolic rate (BMR). It is real, and it is close to your resting burn.
The maths: about 60 kcal every hour
Your resting burn is the biggest slice of your whole day. One review put it at 60 to 75 percent of everything you burn. A typical adult burns about 1,500 kcal a day just to stay alive. Divide that by 24 hours. You get about 62 kcal an hour, even while you sleep. Smaller adults burn a little less than this. Over 8 hours of sleep that is about 400 to 500 kcal gone, just to keep you alive. Your night is never wasted.
Where your night burn goes
Your resting burn is not one thing. It is the bill for many organs working all night. Here is roughly how that energy gets spent while you sleep. The numbers are shares of your resting burn.
How the night burn fits your Burnie maths
The bottom line
Yes, you burn calories while you sleep. About 400 to 500 kcal over 8 hours for a typical adult. That is like your body eating 3 to 4 rotis in the night, just to stay alive. So the hours in bed are not wasted. They are part of your deficit. Sleep well, log your food, and let Burnie do the maths. Burnie is FREE, so the number is never a bill.