To summarize, the idea is that high partial pressure of CO2 causes blood pH to change, which influences the body’s regulatory mechanisms and eventually leads to obesity.
At higher altitudes the carbon dioxide fraction in the air is unchanged, but the partial pressure is lower. I’d expect that lower partial pressures of CO2 would mean less effect on blood pH.
Perhaps it is carbon dioxide. Here is a paper on it:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3341709/
To summarize, the idea is that high partial pressure of CO2 causes blood pH to change, which influences the body’s regulatory mechanisms and eventually leads to obesity.
At higher altitudes the carbon dioxide fraction in the air is unchanged, but the partial pressure is lower. I’d expect that lower partial pressures of CO2 would mean less effect on blood pH.
This was my guess too, but they later did another study with rats and it did not show significant effects.
https://sciencenordic.com/climate-change-denmark-obesity/four-years-later-is-co2-making-us-fat/1440745