Calorie difference in Strava and Garmin Connect

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Skunkworks
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Joined: Wed Jan 13, 2016 12:25 pm
Location: South Korea

by Skunkworks

Hi weightweeeeenies!

I am confused about calories in garmin connect and strava.
Let me show you some examples.

Riding 1)
Garmin connect
Work = 3366 KJ, Calorie = 5630 C
Strava
Work = 3344 KJ, Calorie = 3729 kcal

Riding 2)
Garmin connect
Work = 3270 KJ, Calorie = 6629 C
Strava
Work = 3147 KJ, Calorie = 3509 kcal

I used heart rate monitor and power meter.
Body weight and weight of my bike have been set as same in both gramin connect and strava.
Total work is almost same in both sites, but calorie has a huge difference.

I guess it is because two sites have used different calorie definition.
Garmin changed calculation method from normal 'calorie' to 'food calorie', which uses capital C as a unit.
However, strava used a normal and widely used definition of a calorie, which uses kcal as a unit.

In this sense, garmin's calorie means that I have to EAT that much of calories of food.
And strava's calorie means that actually burned and used calories in my body.
(I used 'actual' but, in truth, this calorie is also an estimation value.)

So far, it's all of my understanding about the calorie difference btw garmin and strava.
I don't know whether my understanding is correct and I have missed something.
Thanks! :D

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mpulsiv
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by mpulsiv

It's not only calories, every metric is skewed (e.g., speed, distance, elevation, duration). Based on my observations, Strava algorithm round off. I use both but for accuracy I rely on Garmin Connect.


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boysa
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by boysa

Your best bet is to look at the work performed (kJ) from your Garmin and go with that as your calorie expenditure. It may not be perfect, depending on your individual body's efficiency, but it's close enough. The other numbers are junk.

1 Calorie = 4.184 kJ ... However, the body is only around 20-25% efficient, therefore we can say 1 Calorie = 1 kJ.
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cobrakai
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by cobrakai

boysa wrote:Your best bet is to look at the work performed (kJ) from your Garmin and go with that as your calorie expenditure.


+1. This has typically worked out well for me. I've found strava to usually be a little high, around 10-20 percent. Those garmin numbers are massively high unless there was a unit change or something.

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ergott
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by ergott

boysa wrote:Your best bet is to look at the work performed (kJ) from your Garmin and go with that as your calorie expenditure. It may not be perfect, depending on your individual body's efficiency, but it's close enough. The other numbers are junk.

1 Calorie = 4.184 kJ ... However, the body is only around 20-25% efficient, therefore we can say 1 Calorie = 1 kJ.


I've been using this formula for slow weight loss and it's been spot on. I don't trust any calculation that tells me my caloric intake should be significantly higher than my kJ expended.

I've lost about 5kg in a little over 2 months. That's while keeping a pretty decent training/riding load (currently CLT of over 70). I haven't felt malnourished or weak on any of my rides.

11.4
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by 11.4

You can't expect Strava to be that accurate. It's not going to know your metabolic efficiency from Peter Sagan's. Your Garmin data may be better, but even so, there are so many variables in caloric consumption and weight loss that Garmin will only give you an estimate. As Boysa said, you can calculate energy consumption and then go to a caloric expenditure from there. But even then, just using some estimate from Garmin or otherwise leaves you open to major inaccuracies, plus its calculation of kJ is subject to a lot of error. The best, within the scope of the equipment you have, is to record kJ readings from your Garmin, track your food consumption to the last calorie, and then see how your weight does. You can then calculate directly from Garmin kJ estimates (which hopefully are at least consistent, even if inaccurate in absolute terms) to pounds lost. When you have that, you at least know how to work out or eat to achieve a specific change in weight.

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boysa
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by boysa

I'd go so far as to say Garmin's kJ numbers are not "estimates" at all. It's a pretty simple equation, really, and you can even do it yourself.
"Deserve's got nothing to do with it." William Munny

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ergott
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by ergott

Do you have your heart rate and FTP zones inputted correctly? If not, that will throw things off. Part of the calculation is what zones you are in.

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oreoboreo
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by oreoboreo

My strava showed my watts way off compared to Connect. For some reason when I signed up for Strava it did not save my weight and had it at 384 pounds. Which really made the watts look great. However It should have been 165lbs...

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