A blog for (semi) athletic middle-aged men (and women) holding on to (the last vestiges of) their youth
by training for and competing in running, cycling, swimming and triathlon events!

Sunday, January 6, 2013

Do Fat Guys Burn Calories Faster?

I'd much prefer riding outside than on my indoor trainer, but the
winter months in Colorado make it a necessary evil.
A week or so ago I posted something on Facebook about riding my 25 miles on my Cyclops Fluid2 bike trainer and burning 1,929 calories. A friend of mine from Texas, who is a lean, Ironman triathlete, asked how I was burning so many calories, saying he'd only burn about 800-850 calories during a similar workout over and above his basal metabolic rate (essentially the number of calories you'd burn lying in bed*).

"Are you burning more because of the cold or altitude?" he asked. "I could drink a lot more Shiner if knew your secret."

I had to admit that I didn't have any secret. My calorie numbers were based simply on what my Garmin Edge 705 tells me. But I have often wondered why I seem to burn more calories than other people I ride and run with so I did some investigating and found some plausible answers.

My first theory was that maybe I burn more calories than he does simply because I am taller and weigh at least 40 lbs. more than he does. Turns out there is some credence to this theory. According to this article on Livestrong.com, "A 20-lb. weight difference can translate to a more than 10-percent increase in calories burned for some activities. For example, if you weigh 160 lbs., you'll burn about 10.3 calories per minute swimming the crawl at a moderate pace. However, if you weigh 180 lbs., you'll burn about 11.6 calories per minute."
I would have burned 30 percent more calories as Fat Daren at 270 lbs (at left in Dec. 1995) than as the skinnier version at 210 lbs (at right in Sept. 2000)

But that still doesn't explain how I could burn more than twice the calories my friend burns in the same workout. If I weigh 40 lbs. more than him I would only burn 20 percent more calories. So if he burned 850 calories riding 25 miles in 75 minutes (average 20 mph) I should burn 1,020 in a similar workout. That still leaves about 900 calories unexplained.

I've always thought the Edge might be overestimating calories and a quick Google search of "Garmin Edge calories" confirmed my suspicions. One glowing review of the Edge 705 found little to fault with what they called the "most useful bit of cycling-orientated electronics we’ve ever used." However, the review said, "We did find that the Edge 705 substantially over-estimates the number of calories you’ve burned. According to Garmin, the best algorithms for calorie consumption are protected by patents, so it’s best to treat this feature as a way of comparing rides for effort. If you eat to replace the food you have just burned, you’ll turn into a blimp." Bummer. Not the answer I was looking for!

So how much is "substantially"? And just how many calories have I consumed thinking I could "afford" them based on what my Garmin was telling me? Is this why I gained 10 lbs over the holidays?!

OK, time for another confession. I don't count calories. I just eat. And I workout. I track my weight and if it goes up I try to decrease calories consumed and increase calories burned. I go with my gut, literally and figuratively. So I can't blame Garmin for my Holiday 10. But I can't keep eating like I did during the holidays and expect to lose it, either. As they say, great abs as made in the kitchen, not the gym.

Ride on!


*I found an online BMR calculator that says a 6'4" tall, 215 lb., 48-year-old male would burn 2,044.25 calories per day (2,000 is considered "average"), or about 85 calories an hour.

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