Measuring Caloric Comsumption
 

i am wondering how other track their calorie consumption for thier workouts. i have a stationary bike that meaures resistence/speed/etc, but not heart rate and for an hour it usually says 375 cal, but if i were to plug in the same metrics into mapmyride.com it says 420 cal consumed.

in addition to that, just got a new cyclocomputer with a HRM, cateye v3, and yesterday it says 543 cal consumed. albeit yesterdays training ride was more intense than the other two days, this is a large window of potential consumption. and for me, who is trying to gain wieght (yes, you read that right, gain, though mostly muscle) i need a realtively accurate measure of cal consumed so i can be sure to overeat the desired amount each day.

Splitting hair, but it's calories burned. When people say consume they usually mean how much they ate. Anyway to your question, short of getting a power meter it is all a guesstimate. Even then it's a guesstimate since you need to account for your BMR.

All of that is based on statistics. The only way to really know how many calories you are burning is in a lab, with gas exchange. It measures how much oxygen goes in and how how much goes out, as well as how much co2 is produced. From that you can determine how many calories you are burning, as well as how much of that is fats vs. carbohydrates.

Edit: Even a power meter won't tell you how much you are really burning, only how much work you have done. To convert from mechanical work (kJ) to food energy (kCal) you have to make an assumption about your efficiency (typically 20-25%). Note that if you do the lab test with a power meter you can determine your actual efficiency...

thanks guys.

obviously theres no real way to no exactly waht youre putting ou without extensive testing; i was just looking to see how other base there cal burning. i would think its better to use the cyclocomputer as its based off of everything (heart rate, resitence via hr, speed, and cadence) and other methods will only use a certain number of those variables.

FWIW, i am going to use an average of the two highest reading i get, so roughly, 500 cal per hour for me during regular training.

A physicist I ride with says that what with unit conversions and efficiency factors, kJ about equals kCal. He says it's plenty close enough. Take a look at your records and see if that seems right to you.

As I said you have to make an assumption about your metabolic efficiency in turning your food/stored energy into mechanical work. There are about 4.2 kJ in a kcal (food calorie), so if we were 100% efficient, we would only need to eat about .24 calories for every kJ our power meter shows us. But we are not that efficient. Testing has shown that most people are between 18 to 24% efficient. So if you assume 24% efficiency, then 1kJ would be 1kcal, but if you took the other end of that, you are looking at a factor around 1.15, and that's a big difference.

understood and thank you for going into such detail...

i am doing this cycling study for a new powerade drink and they are giving me the whole max power, vo2, etc tests next week ( cycling study ) and believe that they will be doing efficiency tests over the next five weeks to measure the usage of the product (they specifically said that they would be measuring intake and exit of gases, so i think they will be doing what you referred to earlier. this would really benefit me and give me honest to goodness numbers to work off of for diet control.

What are you using to track caloric intake/output? I've been using www.about.caloriecount.com and like it but was wonder if anyone was using something else they liked.

I like spark people. You can easily add and store custom foods, food groups, and even recipes.

i also use calorie count for things that dont have nutrition labels and just keep track on my BB

i've been using this: http://www.thedailyplate.com/

I'm using onlinefitnesslog.com it's excellent - has a workout tool where you enter what you did & for how long and it calculates calories burned... also has the daily calorie counter, shows you carbs / fats / protein pie chart percentages, shows your daily calorie intake vs. expenditure, you can track you're weight, sleep, measurements, heart rates, all sorts of stuff. for free. Super easy to use too.