Calories (Read 144 times)

A person with BMI between 22 - 26 should have a BMR of about 65 - 75 calories per hour.  So, a "rest" day/night should still burn about 1550 - 1800 calories.

I'd argue that you should never view a fitness band/tracker as anything more than a rough estimate. They usually derive your sedentary calories via a basal metabolic rate calculation (for your given height/weight/gender) and then factor in additional calories based on some combination of steps taken, heart rate, skin temperature, and skin moisture. It's very imprecise. Generally a "sedentary lifestyle" is "BMR x 1.2," and most formulas for BMR are pretty similar. The one that's probably the most accurate is "65 + (6.2 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)" If you plug your info into that and then multiply the result by 1.2 (to account for calories burned from standing, walking, thinking, etc that go beyond pure metabolic functions like breathing and digesting food...the latter of which is your BMR), you'll basically get what you burn in a day with no exercise. Of course, there are other factors; For example, more sleep=more HGH=higher caloric burn; there's residual afterburn effect from past exercise days later (i.e. a day of rest after racing a 5k is not the same as a day of rest coming after a day of sitting at a desk all day); more stress=higher cortisol and insulin resistance=slower metabolism, etc. But basically, BMR x 1.2="sedentary calories."

On a day with running you can calculate your calories burned rather easily without a fitness tracker. Just type your distance and time into a "VO2 from race" estimation calculator online. Take your VO2 in mL/kg/min and multiply by your weight in kg's. That's your mL of O2 used per minute. Divide by 1,000 to get it in L of O2 per minute. Then divide by 0.83 since it takes 0.83 L of oxygenated blood to burn a gram of glycogen. Then multiply by 4.16 since each gram of glycogen burned costs 4.16 calories. Then multiply by the number of minutes you ran. Take the final result as your calories burned on the run. Interestingly, these results are always pretty much spot on with online calculators that simply ask for the average HR and time spent running to calculate total calories burned, suggesting such calculators (which are presumably what HR based fitness trackers are based on) are basically using the same formulas. In other words, you can pretty much calculate all your calories by hand without an expensive and inconsistent tracker. It should also be noted that there can be an afterburn effect for runs of 70% of VO2 or higher (up to 37%), so you can take the calories burned from running and multiply by 0.37 and add that to the original amount to get a full total. Adding this full total to your "sedentary calories" is roughly your total for the whole day, assuming there was no other major exercise.

 

Is there any way you can have a heart rate monitor too ?  I run with a heart rate belt and it helps calculate calories burnt very accurately, and occasionally if I don't wear it or it's battery dies (rarely) the calorie count is wrong.

I would think HR would be more accurate, but I was trying to avoid the wrist HRM since it sucks so much battery power.  I'll give it a try though just to compare.