To find out how many calories are burned a day without exercise, you need to know your body fat percentage or have a reasonable estimate of it.
Finding out how many calories I burn a day without exercise, or what your BMR is, depends on how your body composition of fat and fat-free tissue. (muscles, bones, organs, etc.). You need to know this because fat is less metabolically active than fat-free tissue.
For example, if a 220 lbs man has 35% body fat, his BMR will be 2135 calories a day. But a man of 220 lbs with only 15% body fat would have a BMR of 2515 calories a day.
As you can see, your body composition is the factor for how many calories you burn per day.
So, how many calories are burned a day without exercise? You need to know three things:
- Weight in pounds
- Body fat percentage
- The magic equation
Your weight and body fat percentage are your parts, so only you know these.
However, we will share the equation with you now:
- Weight x body fat percentage = body fat
- Weight – body fat weight = fat-free weight
- Body fat weight × 9 = calories burned by fat
- Fat-free weight × 28 = calories burned by fat-free tissue
- Calories burned by fat + calories burned by fat-free tissue = BMR
For example, we will use the above example at 220 lbs, 30% body fat from before.
- 100 × 35% = 35 kg body fat weight
- 100 – 35 = 65 kg fat-free weight
- 35 × 9 = 315 calories burned by fat
- 65 x 28 = 1820 calories burned from fat-free tissue
- 315 + 1,820 = 2,135 calories BMR
So there you have it.