Questions About "Calories Burned" Calculations

[jay5r]

I've been tracking heart rate and calories burned while working out with a Polar H7 chest band connected via Bluetooth to the Heart Graph app on iPhone. I know the heart rate is accurate, but I have questions about calories burned values that I get from the app. Specifically I wanted to know how many calories I burned working out vs spending the same time laying on the couch watching TV. If you need to burn 3,500 calories to lose a pound of fat, then that's actually 3,500 over some baseline of calories burned for sedentary activity (assuming a consistent diet that maintains your current weight).

So I monitored myself for a half hour last night while watching TV and it came out to 4.73 calories burned per minute watching TV. But that makes no sense. That means if I watched TV all day I'd burn 6,800 calories (I wish!). Based on the Mifflin St Jeor & Katch-McArdle formulas body burns somewhere in the neighborhood of 2,950 to 3025 calories a day, so 6,800 calories watching TV all day isn't even close to reality.

So now I'm seriously questioning the whole "calories burned" values that I'm getting. From what I'm reading the whole calories burned thing only really works "properly" with steady-state cardio. So it's probably not going to work with TV watching and I'm guessing it doesn't work properly during weightlifting either (since that's really spikey).

So two questions are:

1. How do I get accurate calories burned for workouts that include things other than steady state cardio?
2. How do I determine the rate at which I burn calories during sedentary activities?

[Boss Man]

Hi Jay, good to speak with you.

To be honest, such calorie measuring apps / devices are only a guide anyway.

For example if you want to know calories burned accurately to any degree, you'd need to use the same type of exercise bike, at the same time of day, made by many different manufacturers and setup and used exactly the same way, so then after several days you'd have some indication of what looks more "the norm", because you're replicating the same circumstances everyday.

As for what you burn when you're sedentary I wouldn't worry about that. Yes you lose 1lb of fat if you burn an additional 3,500 calories per week, but what you're burning when active versus sitting down, needn't be such a need to know thing for anyone really, as electronic devices or apps to track this are guides only and you'll know you're getting somewhere if you're overweight and your weight is going down.

[jay5r]

I did more research and found that the "calories burned" calculations are only really accurate for steady state cardio where you get into at least "zone 1". They cannot be used for sedentary activity, like watching TV. (For those activities just take a fraction of your BMR/RMR.) Even more disappointing was realizing that there is no easy & accurate way to determine the calories burned during weightlifting.