Your body is burning calories all day everyday. You burn calories for your body to function so yes while you are sleeping you continue to burn calories and your Fitbit will of monitored this. I have not long woke up and I have burned 700 calories in my sleep. The human body burns around 1800-2000 cals depending on your size, age gender etc a day without activity for it to function. The more active you are the more you burn those calories. I do around 20,000 steps a day and I swim on some of those days also. I burn about 3300 calories. If I did nothing all day I would still burn those 1800-2000 calories a day but if I chose to eat more than that then I become fat. If I chose to eat less than that I would become thin. If I chose to eat that daily amount of calories, did no activity at all my weight would remain the same which is why some people just forever maintain their weight with no exercise at all. I’ve seen a few people wonder how they are burning calories in their sleep, your body has to get energy from somewhere to function as even sleeping your body has work to do,
The human body burns around 2000 calories a day without any activity, it is how the human body functions. This is why we are set that amount of calories a day to consume. 2000 for women and 2500 for men. Every part of your body burns calories to function and when you are asleep your body still needs to burn calories to keep your heart and lungs going and everything else. If you consumed 2000 calories a day, did no activity at all you would maintain whatever weight you are as you are only consuming what your body needs. If you are consuming more than this in a day and still doing no activity then you will start to gain body fat or loose body fat if you are under eating those calories. People who exercise a lot have to consume more calories in a day as their body will struggle to function and become very hungry and if they wanting to just maintain their weight they can eat the amount of calories they have burned. So I burn around 3300 cals a day, if I want to maintain I could eat that amount of calories but I need to lose fat so I make sure I have a 750 deficit on a daily basis and consume around 2500 cals to keep my body going for my activity levels and I lose 1.5 pounds of body fat weekly. I still get hungry sometimes even on 2500 calories as I’m burning 3300 but I must lose body fat and try to consume food that keeps me fuller for longer. When I woke up my body already burned 750 cals in my sleep as my Fitbit knows my activity levels and calorie consumption, weight etc etc.
