Calorie consumption queries.

krauuk

Hi All.

Back to cycling after a long flirtation with motorbikes, beer, guitars and fine foods and also some ill health, and fitness seems to be returning but I have noticed something odd. I record all my rides on connect.garmin and have been doing so for the last ten years or so.

Here is a ride from last year:

https://connect.garmin.com/modern/activity/2239182787

I wore no heart rate monitor. 2108 calories consumed.

Here is a ride from the other day:

https://connect.garmin.com/modern/activity/3337152133

Calories consumed 1011

For this ride I did wear a heart rate monitor with fresh batteries. The rides seem roughly comparable but the calories consumed are roughly half. I could rationalise this by saying that the HRM allows a more accurate assessment of the work I'm doing but:

https://connect.garmin.com/modern/activity/19898547

This ride seems again comparable but I did wear the HRM and the calorie count is much higher. 1897.

I went to this site:

https://caloriesburnedhq.com/calories-burned-biking/

Here I entered the stats for the second ride, currently I weigh 268 pounds (I am 6'3" in my defence...), 108 minutes of cycling, 22.56 miles, 12-14mph. This site gave me a calories consumed figure of 1838 as opposed to 1011 that Garmin reported.

Further to the mystery, my partner and I did the same ride today, separately, and she is much lighter and slower than me yet she burnt more calories than me! I was sitting at 130-140 bpm for nearly an hour and only burnt 690 calories whereas she burnt over 700 and admits to some walking. Any boffins know what is going on here?

I understand that I shouldn't worry too much about the calories, just move more, eat less etc and that is the plan, I'm just really curious about the glitch.

I understand that there have been some glitches on the Garmin site lately, maybe I am just seeing a manifestation of this, or is there something I'm simply not understanding here?

Thanks.

whyamihere

Without a power meter you may as well use a random number generator, it will be about as accurate. Even with a power meter you're guessing at your body's efficiency, but at least you can work out how much energy was used on making the bike go forwards.

aberdeen_lune

Just tried that calories burned site calculator and it estimated the ride I did today at 3,800 calories Garmin gave me 2,600. It was a 3.5 hour steady ride my rough calve is 700 calories per hour if working reasonably hard say averaging 215watts it thereabouts. So for me Garmin is more accurate.
I’d just go with the rough 700 an hour for a hard training ride and 500 per hour for a pootle.

sloppyschleckonds

Ive spotted the problem"

"Took the Kinesis. Not too bad fitness wise, had a bacon roll."

maryka

My Garmin is usually pretty accurate in calories burned using HR when I've compared that to kJ from my powermeter on the same ride. Calories = kJ means 24% efficiency which is close enough for most people. Make sure your body weight is correct in the Garmin though.

(1 calorie = 4.184 kJ)

cycleclinic

Unless you have s power meter there are too many assumptions, mainly CDA and rolling resistance that will make any auto calculation of calories consumed a pointless number.

With a power meter all I know is the work done in moving the bike, not the addition energy used in keeping me warm on a cold day. On the bike for 9 hours today and even with the power meter I still have no idea not finished care how many calories I used or transferred from stored chemical energy to hear mostly.

The carlories used even with the power meter measuring work done assuming an ratio of energy lost as heat to energy transferred to useful output.

cougie

Those figures are way over. 500-700 per hour does seem far more sensible than the calcs.

keef66

With a functioning HRM my Garmin usually estimates I've burned around 500 cals per hour, which I feel is about right. Without the HRM it overestimates by about 80%.

Yesterday I did a ride which was similar in length / duration to your 2nd example, 21 miles, 90 mins, 13.5mph.
The Garmin + HRM calculated just over 700 cals. Your website reckons 857, so not massively different. You clearly burned more calories on account of the extra weight you're carrying. The minor discrepancy between you and your wife is likely just down to the difference in your weight vs ride duration.

But as you say, it's best not to worry about calories allegedly burned, and just concentrate on moving more and eating less. If weight loss is your primary objective then diet is many times more effective than exercise.

I found out the hard way; despite doing a lot of cycling I was always able to consume more calories than I was burning, and my weight kept going up. It wasn't till I happened on the 5:2 diet that I was able to get my weight under control.

ugo.santalucia

Assume 500 KCal per hour for normal/brisk cycling and something like 800 for race pace. Changes a bit with body weight, fitness level etc, but not a lot.

Any app that claims to measure calories is a con... rely on the very basic figures above

stueys

ugo.santalucia wrote:

Assume 500 KCal per hour for normal/brisk cycling and something like 800 for race pace. Changes a bit with body weight, fitness level etc, but not a lot.

Any app that claims to measure calories is a con... rely on the very basic figures above

Those numbers broadly tally with what I get from my PM so a good starting point.

Pross

keef66 wrote:

With a functioning HRM my Garmin usually estimates I've burned around 500 cals per hour, which I feel is about right. Without the HRM it overestimates by about 80%.

Yesterday I did a ride which was similar in length / duration to your 2nd example, 21 miles, 90 mins, 13.5mph.
The Garmin + HRM calculated just over 700 cals. Your website reckons 857, so not massively different. You clearly burned more calories on account of the extra weight you're carrying. The minor discrepancy between you and your wife is likely just down to the difference in your weight vs ride duration.

But as you say, it's best not to worry about calories allegedly burned, and just concentrate on moving more and eating less. If weight loss is your primary objective then diet is many times more effective than exercise.

I found out the hard way; despite doing a lot of cycling I was always able to consume more calories than I was burning, and my weight kept going up. It wasn't till I happened on the 5:2 diet that I was able to get my weight under control.

Whilst I agree with that if you are exercising whilst dieting (rather than exercising instead of dieting) you still need a reasonable idea of the calories consumed otherwise if you just eat your normal intake you'll end up with a massive, unsustainable calorie deficit e.g. I'm currently aiming for 1500 calories a day when sedentary (just under 500 kcals below my BMR) but yesterday I did around 2 hours of moderate pace running and a 45 minute cross country race which would have used all that 1500 calorie allowance so I need a rough idea of how much extra I need to eat or I'd soon be in no fit state to do anything.

keef66

I agree that combining exercise and diet is trickier, and you do need to properly fuel workouts. But without overestimating calories burned and eating too much...

I've never estimated my BMR or looked that closely at my daily calorie balance, but I know that if I end up riding on a 600calorie day I can only realistically expect to do an hour at a moderate pace.

On a normal eating day I'll ride as far / fast as I can in the time available and just be happy that I've burned more calories than I would have done sitting on the sofa.
The appeal of 5:2 is that I'm not calorie counting 24-7, which I find incredibly tedious. I just know what I can eat on diet days to hit the 600 cals and the other 5 days eat whatever I like. Obviously if I massively overeat, the 2 diet days are less effective...

webboo

Shirley if you are training on a fasted day, you should have sufficient calories stored in the form of Glycogen from what you consumed the day before. Which would enable you to perform a high intensity workout.
Doing an endurance ride the day after fasting would also work, if you have trained yourself to by efficient at burning fat.

Tyresome

23 calories per mile is thought to be about right.

webboo

Tyresome wrote:

23 calories per mile is thought to be about right.

How does that work if you are doing hill repeats or intervals. You are going to have a high heart rate and be using a lot more power than someone pootling at 12 mph.

Tyresome

Webboo wrote:

Tyresome wrote:

23 calories per mile is thought to be about right.

How does that work if you are doing hill repeats or intervals. You are going to have a high heart rate and be using a lot more power than someone pootling at 12 mph.

This is a guesstimation from British Cycling, as you can see they assume 23 calories per mile. This based on an average of averages, and is for the ‘average rider’ riding ‘average routes’ at ‘average intensity’. Obviously exact figures depend on exactly what you’ve done, but Strava averages and this assumption from BC seem to have good correlation. Personally I’ve found that basing my calorie intake on these guesstimate figures seems to work as I’m not gaining or losing weight, which tells me they must be close.

keef66

Webboo wrote:

Shirley if you are training on a fasted day, you should have sufficient calories stored in the form of Glycogen from what you consumed the day before. Which would enable you to perform a high intensity workout.
Doing an endurance ride the day after fasting would also work, if you have trained yourself to by efficient at burning fat.

I don't do training, I just ride the bike to maintain some semblance of fitness. On a fasting day if I ride it's generally in the evening, so about 24hrs since I last ate, and if I really push it I can feel quite peculiar. And then the next day I'm ravenously hungry which is a bit counter-productive.

On the following normal day an evening ride would come after 24 hours of eating, so I can give it some welly if I'm so inclined.

Casual observation would suggest I haven't trained myself to be efficient at burning fat. There's still quite a lot of it to shift, put it that way

imposter2.0

Tyresome wrote:

This is a guesstimation from British Cycling, as you can see they assume 23 calories per mile. This based on an average of averages, and is for the ‘average rider’ riding ‘average routes’ at ‘average intensity’. Obviously exact figures depend on exactly what you’ve done, but Strava averages and this assumption from BC seem to have good correlation. Personally I’ve found that basing my calorie intake on these guesstimate figures seems to work as I’m not gaining or losing weight, which tells me they must be close.

So in other words - '23 calories' is a completely worthless generalisation :roll:

keef66

Tyresome wrote:

Webboo wrote:

Tyresome wrote:

23 calories per mile is thought to be about right.

How does that work if you are doing hill repeats or intervals. You are going to have a high heart rate and be using a lot more power than someone pootling at 12 mph.

This is a guesstimation from British Cycling, as you can see they assume 23 calories per mile. This based on an average of averages, and is for the ‘average rider’ riding ‘average routes’ at ‘average intensity’. Obviously exact figures depend on exactly what you’ve done, but Strava averages and this assumption from BC seem to have good correlation. Personally I’ve found that basing my calorie intake on these guesstimate figures seems to work as I’m not gaining or losing weight, which tells me they must be close.

So if my Garmin+HRM tells me I've burned over 700 cals in 21 miles that suggests I'm working harder than Mr. Average?

Hang on; 23 calories per mile and 500 cals per hour means that you'd have to be doing over 20mph :shock:

webboo

keef66 wrote:

Webboo wrote:

Shirley if you are training on a fasted day, you should have sufficient calories stored in the form of Glycogen from what you consumed the day before. Which would enable you to perform a high intensity workout.
Doing an endurance ride the day after fasting would also work, if you have trained yourself to by efficient at burning fat.

I don't do training, I just ride the bike to maintain some semblance of fitness. On a fasting day if I ride it's generally in the evening, so about 24hrs since I last ate, and if I really push it I can feel quite peculiar. And then the next day I'm ravenously hungry which is a bit counter-productive.

On the following normal day an evening ride would come after 24 hours of eating, so I can give it some welly if I'm so inclined.

Casual observation would suggest I haven't trained myself to be efficient at burning fat. There's still quite a lot of it to shift, put it that way

When I have tried 5:2 I find I start to get noticeably cold in the evening, it’s a weird feeling. Otherwise I can function ok.

keef66

Webboo wrote:

Casual observation would suggest I haven't trained myself to be efficient at burning fat. There's still quite a lot of it to shift, put it that way

When I have tried 5:2 I find I start to get noticeably cold in the evening, it’s a weird feeling. Otherwise I can function ok.[/quote]

Me too. I eat nothing till about 18:30, and I start to feel cold mid afternoon and get chillier as the day goes on. I like to think I'm fat burning...

itboffin

Consuming too few calories can lead to a decrease in body temperature, which may be due in part to lower levels of T3 thyroid hormone.

aberdeen_lune

I don’t think 23 calories per mile is correct. kJoules is power in watts x seconds /1000. So if I output 184watts for 20.20 minutes I use 224 kJ of energy. Rough calc 1 calories can fuel 4 kJ but I’m 25% efficient so I burn 224 calories for my ride. Ride distance is 9k (this is real figures from my commute). So 224 calories / 5.6 miles equals 40 calories per mile. Garmin says 184 calories therefore 32 calories per mile. I suppose it depends how you calculate average power. Sunday’s ride was 2651 kJ Garmin says 2600 calories so 38 calories per mile, that was a tougher training ride.

I think 23 calories per mile if your pootling along. Most folk will be burning more.

aberdeen_lune

23 calories per mile would work with a 15mph 100 watt average power ride. Energy equals 100 watts x time 240 seconds (1mile at 15mph) divided by 1000. 24 kJ 24 kcal.

Let me know if my calcs are rubbish

cougie

I know you burn about 100 calories per mile running. Cycling is something like 4 or 5 times more efficient than running so 23 calories a mile seems bob on.

38 calories per mile seems too high to me but I guess it depends how hard it was ? Mountainous ?

bobmcstuff

Garmin uses the Firstbeat 2 algorithm for calorie estimation in many of their devices. This is supposed to be accurate to within 5-7% of laboratory measurements and is about as good as any other method a lay person can use to estimate calories burnt (i.e., a reasonable first order estimate) - https://www.firstbeat.com/en/blog/first ... nts-right/ and https://assets.firstbeat.com/firstbeat/ ... mation.pdf

They do give some caveats including that your stats need to be correct and up to date, and you should use the device frequently so the algorithm stays consistent etc etc etc.

Power meter is probably better, but then again I have seen efficiency numbers between 20 and 25% for the conversion from kJ of work done, which could lead to bigger variations than the quoted 5-7% for Firstbeat (although, I don't know if any of their quoted figures have been independently peer reviewed).

Personally I just take all the numbers with a pinch of salt and try not to eat too much, and assume it will all average out in the long run... Seems to work for me. I am not sure that having the calories burnt figure be really accurate is actually that useful in real life, since the estimates of your background metabolic rate are unlikely to be any better, and the calorie counts in food are only averages (in the US apparently it's only a +/-20% figure anyway).

keef66

I don't make any use of the calories burned figures, but it is quite sobering when you realise just how much effort is required for so few calories.

Which in turn explains how it is easy to still eat too much despite doing a lot of exercise...