Heart rate monitor results in halving of calories burned

[worzel]

I got a heart rate monitor from Santa and have noticed a really weird thing. Both my Garmin Edge / Connect and Mapmyride were telling me I was burning about 1500 Calories per hour before hand. But Garmin Connect is now reporting I am doing only half that when I wear the monitor. For the record, I am averaging 140bpm and peaking at 160. What's the go? Does the device have mystically powers that counter wind resistance???

[human909]

Weird? Most calorie counters are't going to give you anything more than a vague estimate. A GPS might give better values in still wind conditions and if configured properly but they are still going to be very rough. Variation of 50-100% is no surprise. Furthermore some devices might calculate "excess" calories burnt not including basal rate, while others may include the basal rate.

A power meter would give you much better values. But to give anything even closely accurate you are going to have to hook yourself up to a VO2 machine.

[eeksll]

does the garmin allow other settings like max hr and the like?

as a guess:
the estimations originally calculated your burnt calories based on a higher physical effort from you. With the HRM it now calulates you as using much less effort.

ps like human909 posted, the numbers have a big fudge factor involved.

[nickobec]

the numbers have a huge fudge factors involved

the original calories burnt is based on the "average" person riding an "average" bicycle at that speed, weight may or may not be factored in. So a decent rider on a decent bike riding at a good speed, while burn a lot more theoretical calories than real ones.

Adding a heart rate, changes the data for the better, calorie expenditure is based on your heart rate hopefully compared to you make heart rate, maybe with your weight figured in. Not perfect, it is still based on "Averages" but hell a lot better that basing it on speed.

[simonn]

That's been my observation too - cycling, running and in the gym doing both strength (i.e. low cardio) and endurance/HIIT (i.e. high cardio) programs. Always ~50% compared to the same rides/runs/programs entered manually into strava/endomondo/myfitnesspal etc or calculated via rules of thumb.

My (gym) personal trainer told me that, for a rule of thumb, if anything claims that you are burning more than around 10 calories a minute it is probably wrong. Another rule of thumb is if you are properly out of breath, you are probably burning around 10 cals/min (max). How often are you properly out of breath for the whole time period you are exercising? IOW, you are probably not even burning 10 cals a minute for the entire ride - so even less cals burned .

Moral of the story. Don't eat the calories you think you exercised . Diet is far more important for losing weight than exercise.

IOW...

[worzel]

Thanks all. My daily commute is about 70 mins each way and while not out of breath (apart from maybe the Duncraig climb) I am breathing fairly hard the whole way so if the reading with HR is around 700 that seems about right. I wonder if those devices deliberately give high values to make the person doing the exercise feel better and hence like the device / recommend it to their friends etc.

I must admit, I have been telling myself "Hey I burnt 3000 Calories today, I can eat whatever I like" and after losing 7kg in the first few months my weight has been the same for almost a year (though my clothes are looser on the waist, but tighter on thighs and calves). If the true additional Calories are only half that then I need to be more careful. Trouble is, there is nothing like a 35km ride to give you an appetite!

[human909]

"Hey I burnt 3000 Calories today, I can eat whatever I like"

Far better to be in tune and listen to your body. If you are trying to lose weight don't ever use exercise as justification to eat more. Even worse to use what a calorie counter says. Only eat more if your body really demands it there is a difference between a bit of an appetite and being ravenous for food because your body really needs it.

(As somebody who at times is at risk of eating too little and has possibly has too little fat reserves, I certainly know what being ravenous feels like. It is totally different from simply having an appetite or being hungry.)

[simonn]

Far better to be in tune and listen to your body.

Hey....

(As somebody who at times is at risk of eating too little)

...I see.

I have the opposite problem. If I listen to my body I would be overweight or even obese within a few months.

Even worse to use what a calorie counter says.

Yes and no. Food diaries/calorie counters (or more precisely macros counters - myfitnesspal) work really well for me. The average sedentary male (i.e. office working male) needs a minimum of 1400 calories a day. I aim for that plus a little. I use gels etc in addition to this for heavy exercise and keep protein intake up (i.e. reduce carbs mostly and fat a bit) to keep muscle mass. Was losing just under a kg a week before xmas encouraged others to encourage me into bad habits .

IOW, use calorie counters to reach a target, rather than to determine how much more you can eat.

[worzel]

Far better to be in tune and listen to your body.

My wife trained as a chef and is a brilliant cook. When she cooks dinner and it smells good, looks good and tastes incredible I go back for seconds. Listening to my body got me into this condition.

[barefoot]

"Hey I burnt 3000 Calories today, I can eat whatever I like"

If you are trying to lose weight don't ever use exercise as justification to eat more.

If I didn't do that, I would probably die.

I've been counting kilojoules for about 6 months now (and have lost about 9kg). Logging everything I eat on MyFitnessPal (which is much less arduous than it sounds). My normal daily energy goal is just under 7000kJ, which should be about what I need to lose a kilo every fortnight just at my normal sedentary state... which is not far from what I've done.

I have a power meter on my road bike, so I get a fairly accurate measurement of how much energy I'm putting out. Granted, there's a bit of handwaving in converting that to how much energy I'm burning, but general consensus is that we're about 25% efficient, so doing 100kJ of work on the bike requires somewhere around 400kJ of food.

It is not difficult to do 1000kJ of work on the bike in a few hours. That equates to about 4000kJ of food - more than half my normal daily diet. I have done over 3000kJ of work on a long fast ride, which would require 12000kJ of fuel to replace.

If I try to do this kind of riding on a 7000kJ diet, things are going to get very messy. I HAVE to eat more to accommodate my exercise. And you'd better believe I enjoy doing so.

That said, it might be better to think of it the other way around - you have to eat LESS if you're NOT getting enough exercise. I prefer to use a sedentary non-riding day as my baseline, learn to eat a sustainable and satisfying day's diet with that much energy, then add to it as required, rather than trying to cut energy from my diet on non-riding days.

But, yeah, I'm talking about significant sessions of strenuous riding to "earn" extra food for the day. And being realistic about the amount of food. A brisk walk down the street to the cafe doesn't earn a full cream frappaccino and chocolate muffin.

Even worse to use what a calorie counter says.

Certainly, you need to be careful of calorie counters over-estimating your energy consumption. Best to apply a very conservative correction factor to such estimates, if you're going to use them as a justification for eating more. But they're a better estimate of energy consumption than "I feel like I've earned a cookie".

Only eat more if your body really demands it there is a difference between a bit of an appetite and being ravenous for food because your body really needs it.

I've spent most of my life failing to do that, which is why I've gone for a full-on data-driven analytical approach this time. Numbers are inflexible and can't be pleaded with. I either eat within my energy target or I don't.

And now I have a feel for what a 7000kJ diet looks and feels like, I don't really need to log everything any more (although an occasional calibration check certainly doesn't hurt).

[toolonglegs]

Is 1500 Kcal per hour even possble... I am a big guy and going off a power meter I know I have to hold TT pace for basically an hour to burn 1000 Kcal per hour.

[human909]

Is 1500 Kcal per hour even possble... I am a big guy and going off a power meter I know I have to hold TT pace for basically an hour to burn 1000 Kcal per hour.

Its possible if you can maintain ~440W at the crank! (A rough assumption of 25% efficiency)

My wife trained as a chef and is a brilliant cook. When she cooks dinner and it smells good, looks good and tastes incredible I go back for seconds. Listening to my body got me into this condition.

I was talking about body cravings not about craving good tasting food. There is a massive difference.

I have the opposite problem. If I listen to my body I would be overweight or even obese within a few months.

It seems you have misunderstood what I intended to say. But well done if your weightless is working.

If I didn't do that, I would probably die.
.....

It seems you have misunderstood what I intended to say. But well done if your weightless is working.

[mikesbytes]

The 1,500 an hour is wrong, the new figure of half (750) is closer to the truth

Google tells me that 200 watts sustained for an hour = 720 calories so you would need to average 416 watts over an hour to burn 1,500 calories

[barefoot]

Here's an idea.

Let's stop measuring in arse-backwards medieval units.

Talking about anything in calories just confuses things.

We measure power in Watts. All our food is labelled in kilojoules. A Watt is, by definition, one joule per second. We know how many seconds are in an hour. At what point does it benefit anybody except for Americans to convert into calories?

Bundle the calories up with gallons, stones and furlongs. Historic novelties, not for everyday reference.

200W for an hour translates to 200 *60 seconds *60 minutes = 720,000 J = 720 kJ of work.

Our metabolisms are ~25% efficient, so 720kJ of work requires ~4*720 = 2880 kJ of nutrition.

Look at the side of the Big M iced coffee you're going to guzzle to quench your thirst from all that riding. 1800 kJ per 600mL serve. Right there on the box. Same units. No converting.

Calories are dumb and we shouldn't talk about them. All the exercise / nutrition software and websites I've seen have options for what units you want to work in. Switch them over to Watts, kilograms and kilojoules. Don't be a dumb American.

[worzel]

I tend to agree that an imperial measurement system founded on base 60 is old-fashioned and difficult. But I was raised in the UK and it took me many years to get my head around kilometers (a bit of a tongue twister compared to miles). I wouldn't know what a Kilo joule was or whether something was good or bad for me. And as for beer, well that just has to be served in pints not ml - not just because its traditional but also because a schooner or midi is a girl's drink!

[uppo75]

I have a similar issue but it is when the ride get loaded onto strava.
My garmin 500 will display a certain amount, the garmin connect will display the same, but Strava will radically decrease the amount of energy burnt.
Here are the examples (in Kj):
Ride# Recorded figure. Strava display
1_______5519___________852
2.______2757___________322
3.______5489___________726
4.______5008___________835

Anyone seen this before?

[human909]

Here's an idea.

++++1000

[kb]

I have a similar issue but it is when the ride get loaded onto strava.
My garmin 500 will display a certain amount, the garmin connect will display the same, but Strava will radically decrease the amount of energy burnt.
Here are the examples (in Kj):
Ride# Recorded figure. Strava display
1_______5519___________852
2.______2757___________322
3.______5489___________726
4.______5008___________835

Anyone seen this before?

Nope, but my guess is Strava is using the power estimations to estimate energy expenditure. You could try multiplying your average power by ride duration to see if there's a correlation.

[CKinnard]

given watts, just multiply by 15 to ballpark your total energy expenditure per hour in kJ.
this only applies to cycling.

keep in mind that when converting to kJ from watts at the pedals, you are not including energy to keep the body alive at rest (BMR), which is about 0.9 Cals/kg/hr, or if you insist, 3.8kJ/kg/hr.

[simonn]

I don't think Strava paid the Garmin tax so they do not have the full access to all the data in fit files. My guess is that they extract what data they can/has been hacked etc and then recalculate it using dog nose what.

[kb]

FIT files aren't that hard to parse and the Strava engineers are pretty cluey.

[kenwstr]

When I started cycling again, I used a torpedo 7 HRM that indicated I burned about 600 kCal/h or 1000 kCal/30 kms.
Energy seemed to relate strongly to distance cycled with speed having little influence.

I was heavier, less fit and the bike was heavier then.

Now I am using an edge and uploading to both GarminConnect and Strava.
My last ride was 58 km 860m gained and lost at 24 kmph ave and MR max 173 ave 148.
Garmin Connect estimates 1193 kCal, while Strava estimates 1263 kCal for the same ride.
By my original monitor this ride should be closer to 2000 kCal. OK, I am lighter now but that's a way bigger climb than those earlier rides so think these factors should compensate to some extent. In any case the GarminConnect and Strava comparison should be valid but seem to be opposite to a previous poster.

Mystery!

Regards
Ken

[toolonglegs]

Here's an idea.

Let's stop measuring in arse-backwards medieval units.

Talking about anything in calories just confuses things.

We measure power in Watts. All our food is labelled in kilojoules. A Watt is, by definition, one joule per second. We know how many seconds are in an hour. At what point does it benefit anybody except for Americans to convert into calories?

Bundle the calories up with gallons, stones and furlongs. Historic novelties, not for everyday reference.

200W for an hour translates to 200 *60 seconds *60 minutes = 720,000 J = 720 kJ of work.

Our metabolisms are ~25% efficient, so 720kJ of work requires ~4*720 = 2880 kJ of nutrition.

Look at the side of the Big M iced coffee you're going to guzzle to quench your thirst from all that riding. 1800 kJ per 600mL serve. Right there on the box. Same units. No converting.

Calories are dumb and we shouldn't talk about them. All the exercise / nutrition software and websites I've seen have options for what units you want to work in. Switch them over to Watts, kilograms and kilojoules. Don't be a dumb American.

Um what's a second? ... 1/60th of a minute... 1 minute is 1/60th of an hour ... whats an hour if not 1/24th of 2 dozen which makes a day

[kb]

Try "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."

[CKinnard]

My last ride was 58 km 860m gained and lost at 24 kmph ave and MR max 173 ave 148.
Garmin Connect estimates 1193 kCal, while Strava estimates 1263 kCal for the same ride.
By my original monitor this ride should be closer to 2000 kCal. OK, I am lighter now but that's a way bigger climb than those earlier rides so think these factors should compensate to some extent. In any case the GarminConnect and Strava comparison should be valid but seem to be opposite to a previous poster.

Mystery!

Regards
Ken

600 Cals/hr for 2 hours sounds plausible when your data is plugged into several well known equations.
It also puts your average watts at around 160, which is also plausible for such a ride.

Doing over 1000 Calories an hour is very high intensity, like 15 x BMR. It would require an 85kg person to sustain 39kph.