Calorie Tracking

krause1cj

Hey All, quick question. My girlfriend has been using one of those online calorie calculators to get an estimate of her calorie burns when she does cardio. However, we’ve noticed that these calculators indicate that when she weighs less, she burns more calories. We tested them, and if the settings are set on a woman, it will say a lighter woman who works out at the same heart rate and amount of time as a heavier woman will burn more calories.

We both know the heart rate calculators aren’t all that accurate, so she undershorts cals burned anyway, but are these things totally broken? Or is there some kind of reasoning to back up why it’s saying a lighter person would burn more? Oddly, it doesn’t do the same when the settings are set to male.

LivingtheLeanDream

A lighter person should burn less.... it doesn't make sense they would burn more but maybe others will enlighten us.

Unknown

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krause1cj

We tried two different calculators. All we could figure was that maybe something was messed up in their algorithms.

apullum

That sounds strange. If weight is the only thing that you're changing in the equation, and everything else (time, pace/distance if applicable, etc.) is the same, then a lighter person should be burning fewer calories than a heavier person if doing exactly the same activity.

However, if something else changed--maybe she's a runner and is running faster now, so she can run farther in the same amount of time than she used to--that would be part of the explanation. It doesn't sound like this is the case for you, but that's all I can think of.

cwolfman13

I've looked at one of those calculators and noticed the same thing. The only thing I can think of is that the algorithm is assuming that a 200 Lb female with an average HR of 130 is doing less actual work than a 120 Lb female with an average HR of 130.

ETA: I burn more calories now in the same amount of time than when I was heavier because I can go faster and further now in the same amount of time than I did when I was heavier. When I was heavier and first started cycling, I averaged around 10-13 mph for a conversational paced endurance ride. I'm 40 Lbs lighter now and much more fit and average 16-18 MPH for a conversational endurance paced ride. So for an hour ride, I go quite a bit further now and am putting in more work than when I was heavier.

That's about all I can think of.

nowine4me

Be a great boyfriend and get her an Apple Watch!!

sijomial

cwolfman13 wrote: »

I've looked at one of those calculators and noticed the same thing. The only thing I can think of is that the algorithm is assuming that a 200 Lb female with an average HR of 130 is doing less actual work than a 120 Lb female with an average HR of 130.

ETA: I burn more calories now in the same amount of time than when I was heavier because I can go faster and further now in the same amount of time than I did when I was heavier. When I was heavier and first started cycling, I averaged around 10-13 mph for a conversational paced endurance ride. I'm 40 Lbs lighter now and much more fit and average 16-18 MPH for a conversational endurance paced ride. So for an hour ride, I go quite a bit further now and am putting in more work than when I was heavier.

That's about all I can think of.

The bolded is a really good point.
My maximum calorie burn rate now is now 20% higher (improved fitness levels) than when I was 30lbs heavier and my resting HR has also dropped 20%.
Fat/not so fit me would have burned far few calories for the same HR as the current lighter/very fit me.

Depending on what the OP's cardio exercise is there may be far better methods than HR to base estimates on.

As for the algorithm anomaly can only think the assumption being made for females is that lighter equals fitter but for men with their higher proportion of muscle/lower proportion of fat that same assumption isn't made and it defaults to moving less weight takes less energy.
Maybe that's reasonable on average (no idea how true that is) but not so much for an individual and really for calorie estimates you want your individual burn not a generic assumption.