Peter Attia· MD
you hook me up to an indirect calorimeter so you're going to put a a a little plug on my nose you're going to put a um a mask over my nose and mouth that mask has the ability to measure the amount of oxygen that I consume because it has a sensor for O2 so it knows that the O2 that's coming in is at 21% the air is coming in at 21% O2 and whatever I exhale is the difference between that so you can now tell how much O2 was consumed and you can have a similar sensor for carbon dioxide so you know how much carbon dioxide is produced so it's very easy to measure consumed oxygen and produced carbon dioxide provided you can completely isolate around the nose and the mouth yeah as you hook a person up to some form of ergometer usually a bike but could be a treadmill a rowing machine or something like that you increase the demand on the muscle so you increase the wattage or the speed or the something you then get out these numbers V2 and V CO2 which are what we just talked about so consumption of oxygen production of carbon dioxide these numbers fit into a relative atively straightforward linear equation called the wear equation and it tells you three things it tells you total energy consumption in uh kilo calories per minute and then the ratio of V2 and vco2 tell you how much of that energy is coming from fat oxidation and how much of it is glycolytic yeah so at any moment in time you can look at a vco2 and a V2 which are usually measured in liters per minute and you can convert that into a total GRS of fat oxidation in a total grams of glucose oxidation per minute yes