# Fifty Plus (50+) - Garmin calorie calculations

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View Full Version : Garmin calorie calculations

TomD77
05-27-11, 01:15 PM
Wouldn't be too surprised if this subject hasn't been beat to death previously but looking at archives here and a number of various health sites, I'm getting answers all over the chart.

I have a Garmin 305 with cadence and HRM programmed with my stats: 210 lbs, male, 62, max HR 172. On my typical solo ride, my cruise speed will be in the 17-19 range, ride average speed will be around mid-15 to mid-16 including hills, warm up, etc, cadence averaging mid-80's, and the climb here inland on the Florida Panhandle will be around 500-700 feet over 30 miles. I try to keep HR in the 135-140 range (80%) for cruising.

Given the above, the Garmin consistently shows energy consumption of close to 65 calories/mile. Depending on where I look on the internet, that figure ranges from ridiculously optimistic to slightly pessimistic.

Could someone shed some light on the huge variation in internet statements of energy expenditure and which is right?

Looigi
05-27-11, 01:29 PM
Check this:

http://www.dcrainmaker.com/2010/11/how-calorie-measurement-works-on-garmin.html

Chaco
05-27-11, 01:48 PM
I'm fairly close to you - 63, 223 lbs. , max HR 172, and same stats on cruise speeds and ride averages.

My last ride was 1 hr. 51 min., 30.0 miles, 2005 feet of climbing, avg. speed 16.3 mph.
Calories for that ride = 938, or 31.2 calories per mile.

I think my reading is far closer to accurate that what you're getting. You could probably cut your Garmin reading exactly in half and get a reading pretty close to reality.

TomD77
05-27-11, 03:58 PM
I'm fairly close to you - 63, 223 lbs. , max HR 172, and same stats on cruise speeds and ride averages.

My last ride was 1 hr. 51 min., 30.0 miles, 2005 feet of climbing, avg. speed 16.3 mph.
Calories for that ride = 938, or 31.2 calories per mile.

I think my reading is far closer to accurate that what you're getting. You could probably cut your Garmin reading exactly in half and get a reading pretty close to reality.

What do you use for measurement? 52% variance seems sorta large: the rainmaker link shows "conventional heart rate level based estimation with general equations" to have an error range of 20%-35%.

BTW Looigi: very handy, thanks for the link!

Chaco
05-27-11, 05:18 PM
It appears that part of the difference may be that the Garmin 500 uses the FirstBeat algorithm, which is far more accurate than that used by the Garmin 305.

Kurt Erlenbach
05-27-11, 08:47 PM
I looked into this in depth when I got a 305 about 5 years ago. I learned two things: (1) Calorie calculations with bike computers are worthless; and (2) even if accurate, it doesn't matter. Here's why.

The only way to get accurate calorie calculations is with a power meter, and even then the calculation is an estimate. There are various algorithms out there for doing calculations, but none are particularly accurate. None take into account wind resistance, and all make various assumptions about fitness (efficiency), road quality, and the like. Even a power meter, which directly measures how much power you put into the pedals, only estimates how many calories you use, because different people need differing amounts of energy (calories) to create the same amount of force. So on-bike calorie calculations in the best of circumstances are not accurate. The guy who wrote Cyclistats software posts here now and then, and he said that most folks burn about 40 calories per miles. I estimate about 35 per mile, but it doesn't really matter, because . . .

The number of calories you burn on a ride is irrelevant. On a long ride, you should eat enough to make up most of your calorie loss. On any kind of ride you continue to burn calories during recovery, which no bike calculator will catch. For a person with an average basal metabolism, you burn about 3200 calories a day just breathing and pumping blood - on a 40 mile ride at 40 calories per mile, you're only burning about 1600 extra calories. But during recovery you burn more, but you should replace most of the calories to help build muscle. And that, Tom, is where the magic is. Exercise increases lean body mass (muscle), which increases basal metabolism, which leads to weight loss all day every day, so long as you watch your diet. Dieting is what causes weight loss, not exercise. Exercise makes you feel good, look good, and augments a diet by increasing daily calorie burn through increased lean body mass. But exercise done right won't cause weight loss because you should replace most calories burned - it's your basal metabolism burning calories throughout the day that causes weight loss (there's about 3600 calories in a pound of body fat). A long ride makes me hungry, and feeding the hunger with high protein, moderate carb food after a ride is good for you.

So don't worry about the calorie calculation on your 305. It's not accurate, and even if it were, it doesn't matter. There are four rules for losing weight: (1) Eat less junk; (2) eat more good stuff; (3) eat less overall; and (4) add exercise. The entire multi-billion dollar weight loss industry is built around those four simple rules.

Allegheny Jet
05-27-11, 09:14 PM
I looked into this in depth when I got a 305 about 5 years ago. I learned two things: (1) Calorie calculations with bike computers are worthless; and (2) even if accurate, it doesn't matter. Here's why.

The only way to get accurate calorie calculations is with a power meter, and even then the calculation is an estimate. There are various algorithms out there for doing calculations, but none are particularly accurate. None take into account wind resistance, and all make various assumptions about fitness (efficiency), road quality, and the like. Even a power meter, which directly measures how much power you put into the pedals, only estimates how many calories you use, because different people need differing amounts of energy (calories) to create the same amount of force. So on-bike calorie calculations in the best of circumstances are not accurate. The guy who wrote Cyclistats software posts here now and then, and he said that most folks burn about 40 calories per miles. I estimate about 35 per mile, but it doesn't really matter, because . . .

The number of calories you burn on a ride is irrelevant. On a long ride, you should eat enough to make up most of your calorie loss. On any kind of ride you continue to burn calories during recovery, which no bike calculator will catch. For a person with an average basal metabolism, you burn about 3200 calories a day just breathing and pumping blood - on a 40 mile ride at 40 calories per mile, you're only burning about 1600 extra calories. But during recovery you burn more, but you should replace most of the calories to help build muscle. And that, Tom, is where the magic is. Exercise increases lean body mass (muscle), which increases basal metabolism, which leads to weight loss all day every day, so long as you watch your diet. Dieting is what causes weight loss, not exercise. Exercise makes you feel good, look good, and augments a diet by increasing daily calorie burn through increased lean body mass. But exercise done right won't cause weight loss because you should replace most calories burned - it's your basal metabolism burning calories throughout the day that causes weight loss (there's about 3600 calories in a pound of body fat). A long ride makes me hungry, and feeding the hunger with high protein, moderate carb food after a ride is good for you.

So don't worry about the calorie calculation on your 305. It's not accurate, and even if it were, it doesn't matter. There are four rules for losing weight: (1) Eat less junk; (2) eat more good stuff (3) eat less overall; and (4) add exercise. The entire multi-billion dollar weight loss industry is built around those four simple rules.

Karlenbach hits it right on the head. There are too many variables to accurately state calories burned. I did a 2.25 hr workout tonight and my power meter says I burned 1,752 calories. It doesn't take into account the two bottles of Gatorade I drank and the 2 packs of GU. The net result is that I rode 47 miles and averaged 20.1 mph and had a net loss of around 1,000 calories and doesn't account for the carbs I ate upon arriving home. Just as Karlenbach says, the important thing is the calories burned when not riding. If you make your body strong it will burn more calories just living. Much the same as a V8 engine that has a lot of power will burn more gas at idle speed than a 4 cyl.

cyclinfool
05-28-11, 05:43 AM
Yes Kerlenbach is essentially correct. There is no formula that will estimate it closely at all. I suspect the only way to get close would be to use a power meter and CO2 output. I for one am now an extremely efficient energy producer. If I used the estimates for calorie consumption I would be a walking skeleton. I calorie count and if I give my self any more than about 35 calories/mile it seems as if I am gaining weight, and these are not cruising miles, these are hard fast miles. For cruising miles I might as well be sitting in front of the TV. But that's me at 50+, at 20- all I had to do was look at the bike and the weight would drop off. So for me - if I consume about 1800 cal/day and ride about 100 miles/wk I loose about 1 lb. I remember when I had ballooned in college to 235 and started riding again, I was able to loose 1/day - (70 lbs in 10 weeks), it 's just not fair.

TomD77
05-28-11, 06:15 AM

Looigi
05-28-11, 07:10 AM
Karlenbach is right on... pretty much. I know plenty of avid riders who are still overweight. You need to know when to stop eating and the only way of knowing is counting calories. Accuracy is good, but if you're controlling your weight and diet by counting calories, estimates are still of value and way better than nothing. Few will spring for a power meter for this purpose. Stick with a method and over time you'll figure out how to interpret and use the results.

Chaco
05-28-11, 07:38 AM
I agree with the essence of what Karlenbach is saying, i.e., that it is your eating and not your exercise that is the key to weight loss. However, I read about a couple of studies in the NY Times that showed that a) the "after burn" of exercise has been greatly exaggerated, and b) the effect of muscle on calorie expenditure has been similarly exaggerated. I'm not trying to say that exercise should be a primary way of losing weight; I'm only saying that many people fool themselves into thinking they can eat more because of these two factors. The study on "after burn" carefully measured people after a hard exercise session, and found that yes, they continued to burn calories at a rate above their basal metabolism, but even after a very vigorous session, it didn't amount to more than 100 calories or so during the entire day.

As for muscle burning more fat, most people view this as the golden bullet of exercise. The fact is, it's very, very difficult to put on muscle, and it's even more difficult to do that while you're losing weight (because some of your muscle is being used as fuel during exercise), and it's even more difficult to do that when you're past 50 and manufacturing less and less testosterone. Strength training will improve your strength, even if you're 70 or 80 years old, but mainly because you're getting muscle that's already there back into shape, not because you're building lots of new muscle. And even if you're young, it's difficult to put on muscle, and virtually impossible while dieting. That's why body builders get into routines where they diet and try to maintain their muscle while doing so, and then eat a lot more and try to convert the extra calories into muscle by upping the weights.

Again, most people think, "oh, I just added a pound of muscle, so I can go eat that 500 calorie muffin," when nothing could be farther from the truth.

I personally don't count calories, because I have borderline insulin resistance. I lose weight by ridding my diet of easily processed carbs -- sugar, white flour, polished rice, HFCS, etc. I get most of my carbs from fruits and vegetables. The only time I break that rule is when I have a hard ride lasting longer than 90 minutes, so that I don't bonk. [Paleo diet for Athletes was very helpful in this regard].

Kurt Erlenbach
05-28-11, 02:45 PM
Chaco - Most of the things I've read say that your basal metabolism is based on your lean body mass. The BMI is an estimate of lean body mass, which is how most folks estimate their daily calorie need. Increasing lean body mass will burn more calories all day every day. That said, you're completely right that adding significant amounts of muscle is tough at our age. That's why of the four rules I posted about losing weight, exercise is #4 - important, but less important than the other three.

Here is a link to one of the very best (http://www.thegreatcourses.com/tgc/courses/course_detail.aspx?cid=1950), and I think most accurate, sources of info on the subject. I'm a big fan of Teaching Company lectures, and this one is one of my favorites. It's worth the price.

BluesDawg
05-29-11, 09:12 PM
The holes in your belt are the best device ever made for indicating the balance of calorie intake vs. calories burned.