How do we know how many calories are burnt?

Question

For example one burns about 200 calories while taking a walk.
Who figured that out and how?

In: 8

Answer 1

>For example one burns about 200 calories while taking a walk. Who figured that out and how?

First off, if you have a thing on your phone or wrist telling you how many calories you burned, it’s mostly just taking a wild ass guess.

Having said that, the way to figure out how many calories you burn during a given activity is to put on a breathing mask while performing that activity, and measuring exactly what gasses you’re in- and exhaling; then with that knowledge you can use algebra to figure out what you used as an energy source and how much of it, which will tell you how much energy you used if you know how much energy those energy sources contain.

Or to give the simplified version, you compare how much oxygen you inhale to how much CO2 you exhale to figure out of you’re burning fat or carbs, then multiply how much of each you’ve burned by how much energy they contain.