that uh in this sort of simple version of how metabolism is supposed to work hey guys hope you enjoyed the episode brought to you by our sponsors at blue blocks go to blue blocks dot com forward slash impact theory for NUMBER_TOKEN off your order or just use discount code impact theory at checkout all right enjoy the episode okay so that you get this confounding mystery you guys are using would we call it the the gold standard of caloric uh expenditure a brief snapshot of what that is i think would help people sure so you drink some it's called the double labeled water technique you drink some water where the you know water is hNUMBER_TOKENo you drink some of the water you drink some water where some of the h's are deuterium and some of the o's are an isotope a different form of oxygen and we can use those as tracers and the hydrogen isotope tracer becomes a tracer of water throughput through your body the oxygen isotope becomes a tracer of of both water and the coNUMBER_TOKEN that you produce when you burn calories and so if we if we subtract the deuterium signal from the oxygen signal the only thing that's left is the coNUMBER_TOKEN you produce every day so it's a precise measure of carbon dioxide produced over the course and we do these experiments over about seven to ten days so it's a pretty good you know snapshot of your life a seven to ten day long snapshot of your life and how much carbon dioxide you produce and you can only produce coNUMBER_TOKEN burning calories and you can't you know so that it's a really good signal of calorie burn um and it's the gold standard for anybody outside of a laboratory and when we talk about calorie burn you mentioned in the book that you don't think most people understand that you're exhaling most of the calories that you burn versus other things that we probably think about it as you know using your muscles or whatever but it's uh it's actually just part of the the metabolic rate of all of your cells as manifested by exhaling the carbon dioxide and we start getting this data back and we're saying wait a second they're not using more energy what's your first leap as to why how that could be possible it doesn't seem possible well no so the first reaction was we i i don't know what your language rules are that we screwed up uh are the first expect i mean that's the first a good scientist always assumes that they screwed up when you get funny results uh and you know i i think we were pretty careful about that so the first thing we did is we we actually used a whole a second way of measuring energy expenditure with calibrated heart rate monitors and cut the same answer so the hodzo we knew the hodges data were real um and then we thought well maybe it's just the hodges then we've now looked at this in uh two other populations of uh sort of foragers in south america very carefully and looked at other data from other groups as well but but um my lab is specifically involved in two other populations of work we looked at this in other species like like a monkey in the zoo has the same energy expenditure as the monkey and a monkey in the wild you know so it's the same everywhere and across species so
START_SPONSOR_TOKEN hey guys hope you enjoyed the episode brought to you by our sponsors at blue blocks go to blue blocks dot com forward slash impact theory for NUMBER_TOKEN off your order or just use discount code impact theory at checkout all right enjoy the episode END_SPONSOR_TOKEN