At the moment it seems when cycling that calories are based off your raw power. For example if you avg 200watts for 60mins you burn 700calories and this runs true no matter how tall or how much you weigh.
This is where the calculation I feel falls apart and becomes inaccurate for alot of people.
Why does Zwift not take into account the persons age, weight, height, ftp etc? Would your calorie burn not be different if you are working at threshold with a very high heart rate and be sitting on 200 watts due to having a low FTP vs someone sitting in zone 1 or 2 because they have a high FTP and their heart rate is super low?
I have noticed if you stop pedalling on downhills you will not burn any calories in Zwift even though your heart could be racing still as you struggled to get up a climb. The moment you start to pedal and power shows up then the calories resume.
Just seems there should be a better and more accurate way for Zwift to recognise the effort and your burn. This would definitely help then those on weight loss journeys who are trying to calculate the burn from exercise etc
I think you may be touching on the difference between mechanical work and metabolic calories or food calories. While the first one is easily measurable by a trainer, the second and third can only be roughly estimated and only after inputting a LOT of very personal information, including what you eat for every meal. It can be depressing to look at that 200 kcals of ramen I ate and calculate how long it will take to pedal it off but it does feel a lot better if I take into account the metabolic energy required to digest, store, and actually deliver that energy, which might turn that 200 kcals into only 50 kcals of work produced. That energy you are still using (metabolically) while coasting downhill after doing a hard effort uphill is part of it. And yeah, it’s complicated!
For the most part, energy burned is directly and linearly related to energy put into the pedals. There are small variations with respect to individual efficiency but for the most part these are in the single-digit-percent range.
There is no consumer-grade better and more accurate measure of human energy expenditure than that of a cycling power meter.
The reason this wouldn’t be that much different is because both of those people are doing roughly the same amount of work regardless of how hard it “feels” for one vs. the other. It takes a certain amount of power over a certain amount of time to do a certain amount of work. One person might be slightly more or less efficient than the other, one might also have a different base metabolic rate, but if both do 200W for an hour they both do the same amount of work in that hour.
Calorie calculations that use weight and HR as an estimate are not as accurate as a power meter in determining how much actual work was actually done.
Now, nothing is perfectly accurate, but if you’re comparing HR vs. power meter calorie calculations, it’s likely the power meter calculations are more accurate.