Bike Forums > Calories burned calculators: which bodyweight to use?
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 09-23-06, 11:15 AM #1 mac They see me rollin' Thread Starter     Join Date: May 2005 Location: Los Angeles Bikes: 2005 Cannondale T2000 Posts: 785 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Calories burned calculators: which bodyweight to use? The Calories Burned Calculators that you find on the Internet all require you to enter your bodyweight. However, it doesn't specify which kind of bodyweight: lean mass, total, specific bodyweight %? i.e. I'm pretty sure a 200lb bodybuilder with 5% bodyfat will burn more calories than a 200lb couch potato with 35% bodyfat. So what number should I plug into those calculators? Does it assume, say, 15% bodyfat? So should I first find out what my lean body mass is then divide by .85 to get the right number to plug into the calculator?
 09-23-06, 12:05 PM #2 DannoXYZ  Senior Member     Join Date: Jul 2005 Location: Saratoga, CA Bikes: Posts: 11,633 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 23 Post(s) It depends upon what kind of calories-burned you're calculating. If you're figuring out calories burned during a workout, then put in your true body weight. If you're calculating calories-burned for maintaining body-heat, you'd want to enter a slightly larger number to account for faster heat-loss (you've got less insulation). Overall, there's a great amount of inaccuracies in these calculators anyway because everyone's body, efficiency and fitness is different. I'd guesstimate that they're accurate to +/-20% at best.
 09-23-06, 03:44 PM #3 kuan Twincities MN     Join Date: May 2005 Location: Salsa, Cannondale, Surly. Bikes: Posts: 2,527 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) People always overestimate their calories burned and underestimate the food they eat. __________________ www.marrow.org
 09-23-06, 03:51 PM #4 caligurl OMG! i'm a DURT gurl!!!!     Join Date: Jul 2004 Location: HOT, sunny socal desert Bikes: 2007 specialized stumpjumper FSR expert, 2006 specialized ruby pro, 2004 specialized dolce elite, 2005 specialized hardrock Posts: 4,939 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) hmmmmmm i've never thought of that... i just always put in my actual body weight... even though i have a lower body fat (i do lift weight so have some muskel!) of course... since i'm small... i know i don't burn the calories that guys burn... plus i've been working out and my body has gotten too efficient so that i don't burn a lot of calories.... i do measure my food to make sure i don't overeat (ok... it doesn't always work!) but i agree... most people do underestimate their food (how many of you actually eat ONE serving of meat... that's 3 oz!!!!! lol!) __________________ OCP and PROUD! "OCP is not just about attitude, it's a way of life!" life's too short to ride a crummy bike..........
09-23-06, 04:19 PM   #5
NoRacer
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 Originally Posted by kuan People always overestimate their calories burned and underestimate the food they eat.
Not always.

Today, I did a metric century on my own while rev'ed up on an ECA stack. It felt harder than the last century I did last weekend, due to a headwind on the leg back home and the effects of the stack.

According to my Timex HRM, I averaged 147 BPM for the entire ride, peaked at 172 BPM (my max on the bike is 186 BPM), and burned 3,710 Kcals.

My BMR for my age and weight is about 1,556 Kcals and the only thing I had before the ride was a cup of grape nuts granola cereal in skim milk and a banana--approximately 550 Kcals. During the ride, I had 2 x 24 oz of Gatorade--160 Kcals per bottle. After resting, I had a can of chili, another banana, and a protein drink--830 Kcals.

So, here's what my "energy" day looked like mathematically:

Code:
```BMR        Activity (Kcal)    Total (Kcal)
1556    plus    3710    equals    5266
Factor    equals    3.4

Food (Kcal)    equals    1700
Debt (Kcal)    equals    3566    1.02    pounds```
So, according to the above, I'm about 1 pound down for the day, if I have nothing more.

Realistically, I'll probably have something else, but it won't be over the 3,566 Kcal debt. I can confidently say that today, my energy expenditures will be greater than my energy intake even if the BMR and Activity calculations are little off.

The reason I'm watching my weight isn't because of a race... no, I'm going on vacation in Cancun. I want to look good im my Speedo.

.

Last edited by NoRacer; 09-23-06 at 04:59 PM.

09-23-06, 06:57 PM   #6
ericgu
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 Originally Posted by mac The Calories Burned Calculators that you find on the Internet all require you to enter your bodyweight. However, it doesn't specify which kind of bodyweight: lean mass, total, specific bodyweight %? i.e. I'm pretty sure a 200lb bodybuilder with 5% bodyfat will burn more calories than a 200lb couch potato with 35% bodyfat. So what number should I plug into those calculators? Does it assume, say, 15% bodyfat? So should I first find out what my lean body mass is then divide by .85 to get the right number to plug into the calculator?
I don't think that the calculators are accurate enough for it to matter. Heart rate monitors will give you a better estimate.
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09-23-06, 08:49 PM   #7
kuan
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 Originally Posted by NoRacer Not always. . blah blah . . more blah
Yeah yeah... you're not estimating. You're actually counting.

Me, I ate at least 3000 kcals at dinner tonight.

Yours truly,

Fatty McWhycan'tIlosemygut
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 09-23-06, 10:09 PM #8 bikeferret better than brand X!   Join Date: Apr 2004 Bikes: Posts: 32 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Is there anywhere to put in your bodyweight and heartrate to calculate calories burned online, ie perform the work that my ****ty heart rate monitor pretends it can do?
 09-24-06, 04:24 AM #9 DannoXYZ  Senior Member     Join Date: Jul 2005 Location: Saratoga, CA Bikes: Posts: 11,633 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 23 Post(s) Neither would be very accurate anyway. Your HR @ 160-170bpm for an hour would represent the kind of work your body can do in its current fitness shape. Compare the same HR to a beginning rider would show them to burn off fewer calories. Compare your numbers to Lance @ 160-170bpm would show he's burning off mroe calories. The only way to accurately determine calories-burnt is to actually measure it. Put a rider in an isothermic chamber and measure how much he heats up his surroundings...
09-24-06, 02:10 PM   #10
NoRacer
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 Originally Posted by kuan Yeah yeah... you're not estimating. ... blah, blah, blah ...
They're all estimates--the calculation for BMR, expended calories derived from an algorithm embedded in the Timex HRM, and the calories assigned to foods from nutritiondata.com. None is exact.

09-24-06, 02:15 PM   #11
NoRacer
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 Originally Posted by DannoXYZ Neither would be very accurate anyway. Your HR @ 160-170bpm for an hour would represent the kind of work your body can do in its current fitness shape. Compare the same HR to a beginning rider would show them to burn off fewer calories. Compare your numbers to Lance @ 160-170bpm would show he's burning off mroe calories. The only way to accurately determine calories-burnt is to actually measure it. Put a rider in an isothermic chamber and measure how much he heats up his surroundings...
In the absence of an isothermic chamber, it's the best one can do to track energy input and output on some consistent and convenient basis.

And, it's apparent from my before and after pics, that my method is doomed to failure :

Last edited by NoRacer; 09-24-06 at 02:33 PM.

09-24-06, 02:25 PM   #12
NoRacer
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 Originally Posted by bikeferret Is there anywhere to put in your bodyweight and heartrate to calculate calories burned online, ie perform the work that my ****ty heart rate monitor pretends it can do?
The problem with such a tool is that it's not taking into consideration the work being done as it changes with intensity due to external (temp, terrain, wind, position on the bike, etc.) and internal factors (hydration status, fitness level, thermoregulation, etc.)

An HRM can sample heart rate at intervals and apply the inferred work load to an algorithm that approximates kcals burned.

09-24-06, 02:51 PM   #13
Tom Stormcrowe
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 Originally Posted by NoRacer The problem with such a tool is that it's not taking into consideration the work being done as it changes with intensity due to external (temp, terrain, wind, position on the bike, etc.) and internal factors (hydration status, fitness level, thermoregulation, etc.) An HRM can sample heart rate at intervals and apply the inferred work load to an algorithm that approximates kcals burned.
http://www.kreuzotter.de/english/espeed.htm

Takes into account wind, grade, speed, type of bike and the only thing it doesn't take into account is HR
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 09-24-06, 07:53 PM #14 Machka  In Real Life     Join Date: Jan 2003 Location: Down under down under Bikes: Lots Posts: 48,454 Mentioned: 50 Post(s) Tagged: 0 Thread(s) Quoted: 1369 Post(s) If you want to lose weight, enter the body weight you WANT to be. There's no point entering your current body weight ... that would only work if you want to MAINTAIN your body weight. Plus, because most people overestimate their calories burned and underestimate the food they eat, entering a lower weight would give you a more accurate reading.