Peter Attia· MD
if you use doubly labeled water you can actually do that over several days but then you also need to you need several days in order to do that yeah so this is really a way of your you're getting uh you're getting carbohydrates in you start oxidizing them that CO2 is also mixed in your blood so it takes a while before the expiration of labeled carbon is also um a good proxy for the amount of carbon carbohydrates that you're oxidizing