# Caloric burn rate in cold weather



## spastook (Nov 30, 2007)

Anybody have any information as to whether or not your caloric burn rate goes up substancially riding in cold conditions. I did my usual 30 mile loop today and burned 1168 calories. It was 18 degrees when I headed out. Typically I'd burn only about 950 calories riding this same route. Ride time was about the same as it always is give or take a couple minutes. An extra 200+ calories is quite a jump, is my system burning calories trying to keep warm?


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## pretender (Sep 18, 2007)

How do you know how many calories you burned?


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## Doctor Who (Feb 22, 2005)

I've read in numerous places that if one is exercising, cold weather has only a negligible effect on calorie consumption.


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## capt_phun (Jun 14, 2004)

If you are using a powertap or SRM & those are the numbers, you were either pushing a harder gear or using a faster cadence as the power units have nothing to do with your body temperature.


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## spastook (Nov 30, 2007)

pretender said:


> How do you know how many calories you burned?



Polar CS200 Heart Rate Monitor gives bike functions, heart rate and caloric burn rates.


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## Wookiebiker (Sep 5, 2005)

If you rode at the same speed as you normally do when warm, chances are you were working harder.

Cold air is more dense than warm air...i.e. thicker. Therefore it takes more energy to go the same speed in cold weather as it does in warm weather. Was your average HR higher than normal during the ride? That could indicate you were working harder than normal.

As for burning more calories when cold....unless you are shivering, chances are you are not burning any more calories trying to stay warm. As long as you are dressed for colder weather you are probably not burning any more calories trying to stay warm as you would on a warm day.


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## jibboo (Jan 1, 2008)

No significant difference until your body temp drops enough for you to shiver. Shivering burns tons of calories, though.

Dave.


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## Kerry Irons (Feb 25, 2002)

*HRM and calories*



spastook said:


> Polar CS200 Heart Rate Monitor gives bike functions, heart rate and caloric burn rates.


It is quite difficult to accurately predict calorie burn from heart rate, and typically predictions from HRMs are 30% or more above reality. Your numbers are, however, pretty close to what you would expect. I'm guessing that your unit uses speed rather than HR to predict calorie burn. That said, at 20F the air is 12% denser than at 80F, so if your speed really was the same as your warm weather rides, the the numbers you report make sense. It is the extra aero drag, not the temperature itself that causes the increased calorie consumption.


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## spastook (Nov 30, 2007)

I'm guessing that your unit uses speed rather than HR to predict calorie burn. 

No, my unit isn't even currently hooked to my bike to provide speed or distance. Caloric burn is determined based on my age, height, weight, resting heart rate, maximum heart rate, and time at a specific heart rate. Today I burned 1168 calories because I was cycling at 78% of my maximum on average for a total of 145 minutes.


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## Kerry Irons (Feb 25, 2002)

*Lucky guess*



spastook said:


> No, my unit isn't even currently hooked to my bike to provide speed or distance. Caloric burn is determined based on my age, height, weight, resting heart rate, maximum heart rate, and time at a specific heart rate. Today I burned 1168 calories because I was cycling at 78% of my maximum on average for a total of 145 minutes.


There is no reliable algorithm to estimate calorie burn from heart rate numbers. It's just a lucky coincidence that your HRM gives you a number that is in the right ball park. People often report calorie numbers here (from HRMs) that are WAY off.


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## M__E (Apr 21, 2006)

*yes..but..*

theres only one simple answer to that one...yes!
but the by how much is very much dependant on the individuals body fat% aerobic conditioning and muscle mass ect, and off course how cold it is :thumbsup:

I very much doubt the HRM is factoring in the temperature into the equation when calculating the calories burned (note: mine measures temp and alt ect aswell..so no smart comments coming back at me with "oh noOoo! ...well mine measures temp and.."


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## M__E (Apr 21, 2006)

Doctor Who said:


> I've read in numerous places that if one is exercising, cold weather has only a negligible effect on calorie consumption.


that depends on how much 'insulation' :wink5:..you have


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## ballboy1360 (Apr 5, 2008)

Cold air is denser than warm air? Where do you guys live?
I realize that at 30% humidity air is denser at 20F than at 80F. But in SC the humidity will never get below 50% in summer and will usually be 50-80% making the air much denser. The amount of water in the air at 90F and 50% is probably 10 times what it would be at 30F no matter what the humidity level. 
Your HR is higher in the cold because it takes more energy to warm the air you breathe and to warm your body after taking in that cold air. I don't know how much more calories you would burn but at 20F you would burn a noticeable amount more than at 40+F. If you are working hard the volume of cold air entering your body each hour is huge. It takes significant energy to counteract that cold.


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## z rocks (Sep 9, 2007)

How bulky is yuor cold gear? Maybe you're overdressed.


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## Kerry Irons (Feb 25, 2002)

*Are you dense?*



ballboy1360 said:


> Cold air is denser than warm air? Where do you guys live?
> I realize that at 30% humidity air is denser at 20F than at 80F. But in SC the humidity will never get below 50% in summer and will usually be 50-80% making the air much denser. The amount of water in the air at 90F and 50% is probably 10 times what it would be at 30F no matter what the humidity level.
> Your HR is higher in the cold because it takes more energy to warm the air you breathe and to warm your body after taking in that cold air. I don't know how much more calories you would burn but at 20F you would burn a noticeable amount more than at 40+F. If you are working hard the volume of cold air entering your body each hour is huge. It takes significant energy to counteract that cold.


Are you happy? I ask, because I understand that ignorance is bliss  

If you would take a few minutes with a calculator, or even just do a simple thought experiment, you would realize that humid air is less dense than dry air. Water weighs 18 gm per mole, while the average molecular weight of "air" is 29. The more humidity the less air (oxygen and nitrogen) you have per unit volume. The effect is small, but it is real. And regardless of the humidity, cold air is more dense than warm air. The temperature effect is large compared to the humidity effect.

The amount of energy it takes to warm cold air in your lungs is miniscule, and it doesn't cause your HR to go up. Do the math before you make these statements. Scientific studies have demonstrated that unless you are shivering, you are not burning more energy just because of the cold air. As noted by a few other posters, colder air is more dense and so if you ride at the same speed, THAT will require more calories.


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## ballboy1360 (Apr 5, 2008)

*Are you thick?*

What do you think will happen if you breathe dozens of gallons and eventually hundreds of gallons of cold air? You will definitely begin to shiver in time. Why do you think warming the cool air is relavant, because the heat comes from inside your body and makes you cold. Airhead.


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## anhinga (Nov 19, 2004)

You absolutely burn more calories doing the same exercise in cold weather that you do when it's warm. The reason for this is that one calorie is the amount of heat required to raise the temperature of one cc of water one degree C. So, it would require more energy to produce that heat when it's cold than when it's warm.


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## ballboy1360 (Apr 5, 2008)

You mean it's not because "water is lighter than air"? LOL!
Can you imagine resistance running in the air to strengthen yourself for when you ran in the "less dense" water?


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## Kerry Irons (Feb 25, 2002)

*Science vs. ???*



ballboy1360 said:


> What do you think will happen if you breathe dozens of gallons and eventually hundreds of gallons of cold air? You will definitely begin to shiver in time. Why do you think warming the cool air is relavant, because the heat comes from inside your body and makes you cold. Airhead.


Your body produces wattage at roughly 25% efficiency. The rest of the heat has to be dissipated in some fashion. If you are getting cooling from breathing and humidifying cold air, then your body doesn't need to sweat as much. The fact that, even when it is cold (most of us) still sweat during exercise should tell you that you are already producing an excess of heat and so breathing the cold air puts no added energy demands on the body. This has been demonstrated in scientific research. If you can cite research to the contrary, please do. Otherwise, . . . 



ballboy1360 said:


> You mean it's not because "water is lighter than air"? LOL! Can you imagine resistance running in the air to strengthen yourself for when you ran in the "less dense" water?


You seem to completely not understand that water VAPOR is lighter than air, and that is what we are talking about here. Humid air is less dense than dry air. It is a scientific fact and has been known for well over 100 years (when the measurement techniques became available). You shouldn't attempt sarcasm when you obviously don't understand the issue at all.


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## Andrea138 (Mar 10, 2008)

Just FYI- one of the responses your body has to cold is called "non-shivering thermogenesis." Simply put, it is your body speeding up metabolism in order to produce more heat... without shivering. This results in more calories being burned.

It doesn't have anything to do with the air density argument, though.


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## pretender (Sep 18, 2007)

Andrea138 said:


> Just FYI- one of the responses your body has to cold is called "non-shivering thermogenesis." Simply put, it is your body speeding up metabolism in order to produce more heat... without shivering. This results in more calories being burned.
> 
> It doesn't have anything to do with the air density argument, though.


I swear that when I come in from a cold ride (or in the past, a surf sesh with water temps in the mid 50s), I am ravenous. I want to eat the house. And I want to nap all afternoon.

So my intuition is that I expend more energy when it is cold, even though I am not shivering during the workout.


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## llvllatt (Jul 23, 2005)

ballboy1360 said:


> You mean it's not because "water is lighter than air"? LOL!
> Can you imagine resistance running in the air to strengthen yourself for when you ran in the "less dense" water?


Talk to any knowledgeable track/pursuit coach about it... they'll tell you that hot, humid air is far faster than cold, dry air.

N2 and O2, which are what "air" is mostly made of are much heavier than H2O, all in gas form


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## Alex_Simmons/RST (Jan 12, 2008)

ballboy1360 said:


> Cold air is denser than warm air? Where do you guys live?
> I realize that at 30% humidity air is denser at 20F than at 80F. But in SC the humidity will never get below 50% in summer and will usually be 50-80% making the air much denser. The amount of water in the air at 90F and 50% is probably 10 times what it would be at 30F no matter what the humidity level.
> Your HR is higher in the cold because it takes more energy to warm the air you breathe and to warm your body after taking in that cold air. I don't know how much more calories you would burn but at 20F you would burn a noticeable amount more than at 40+F. If you are working hard the volume of cold air entering your body each hour is huge. It takes significant energy to counteract that cold.


Air density is a function of:
- temperature
- barometric pressure
- humidity
- altitude (since barometric pressure is usually given for sea level equivalent)

Air density increases as:
- it gets colder
- barometric pressure goes up
- humidity falls
- we lose altitude

Of the above, the effect of humidity changes on air density is very small compared to the others.


Any self respecting track cyclist knows for example that the fastest times are set on hot, low pressure days (think summer storm cell) and at altitude because air density is lower and you can go faster with the same power output.


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## ballboy1360 (Apr 5, 2008)

I saw the density thing as a sorta red herring which is why I egged on the discussion(sorry). Fortunately, for me, ignorance is a state that, as you have done for me, can be cured. Stupidity stays around forever.


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