On average, 42% of an adult man’s body mass is made up of skeletal muscle. For women, that number drops to 36% on average. Contrary to popular myth, skeletal muscles consume about 6 calories per pound per day, not 50. So, if you weigh approximately 180 pounds and are a man, your skeletal muscles will burn around 454 calories per day when you just sit around all day.
Fat cells will burn about 2 calories per pound per day. How much of your body mass is made up of fat cells varies greatly from person to person, but you can use a body fat test to get that number and then calculate how many calories your fat cells burn per day. Average male is 18% - 25%, female is 25% - 31%. Wow, another 64 burned calories for sitting around.
Bone cells burn about 1 calorie per pound. If you are a man, on average about 15% of your body mass is made up of bone (another 27 calories for just sitting around). For women, that number is around 12%. Sit back, relax, burn some calories.