Calories burned on the bike…nobody knows

In a chat the other day with one of my Iron Buddies determined to lose quite a few pounds before racing starts this spring…and a cycling fanatic…I told her that I was working on this post…so here it is 🙂

Seems like a simple enough question you would think…how many calories do you burn riding a bike?

Why is this important?…if you want to lose weight, there’s a HUGE difference in the calculators, so you could think that you’re burning more calories than you actually are.

…like for my 1 hour ride yesterday, the difference between 664 and 1181 calories…so over 500 calories difference…these are the 2 numbers in 2 different programs that I use…multiply that by a 3 hour ride…that’s a 1,500 calorie difference in your daily accounting.

My workout was on my tri bike on the static trainer, 60 minutes, 184W avg, 207W Norm power, with a main set of Hard intervals:

• 10 minute easy warm-up,
• 3 x 3 minutes @ 80-85% FTP (mod-hard) on 1 minute easy rest
• Main Set of 3 x 8 minutes @ 95-100% FTP ( Hard) on 2 minutes easy rest
• then cool down

The first…the 664 calories…is from my PowerTap power meter which calculated 664 kJ of work, which according to the PowerTap manual:

The total work done over the course of the trip or interval is shown in kilojoules. This value is a measure of the total energy expended over the course of your ride. This is roughly equivalent to dietary calories expended.

Enter the same workout into MyFoodDiary, and it gives me credit for 1,181 calories burned (by selecting 16-19MPH).

So which one is right?…turns out, nobody knows…or more properly, the opinions are all over the place…like wildly all over the place.

Here’s just one example from one cyclist in one forum that did a comparison on 4 different monitors, all operating on his bike during 5 actual rides

Respected cycling coach Chris Carmichael puts the bike calorie burn at 8-10-12 calories per minute up to 16 calories per minute when you’re _really_ pushing it…so in my 1 hour, on his scale let’s say 12 x 60 = 720 calories…or was it 13…or 11…you see the problem…since I was pushing it, but not for the full hour…more details in an earlier post:
http://www.irondaughterirondad.com/nutrition/counting-calories/ 

…and trust me when I say there are thousands of other articles and opinions, about all of the variables, and why they’re so different, and all the factors such as your weight, and position on the bike, and hills, or wind, and type of bike, and weight of your bike, and efficiency of the human body, power measured at the wheel not accounting for the rest of the body, and whether it’s calculating incremental calories or total calories, and so on.

The Bottom Line

For me I use a PowerTap, and since it’s generally the lowest calculator of all, I just plug in that number..at least I’ll err on the low side.

…the caution is that if you use _any_ other method, it’s going to give you a higher number…and most of the time, _much_ higher…as we see in the chart above, it could be over double.

If it were me, without a PowerTap, I’d use one of the following methods to get the number closer:

• for an easy ballpark number, I’d use the MyFoodDiary calculator…or equivalent, and lower it by 30%,
• or read  One of many Carmichael articles and use that…he’s one of the lowest on the calorie burn opinions…and also promotes ‘Fast’ intervals as the best way to lose weight and improve your bike speed

Of course, you’d have to think that counting calories is worth the effort for any of this to be of any value anyway…but a discussion for another day 🙂