Everyone ought to read "A Chemical Hunger"(1) which posits that the relationship between altitude and obesity is real(2), and is mediated by lithium in the drinking water.<p>(1)<a href="https://slimemoldtimemold.com/2021/08/02/a-chemical-hunger-part-vii-lithium/" rel="nofollow">https://slimemoldtimemold.com/2021/08/02/a-chemical-hunger-p...</a><p>(2)<p><pre><code> -Higher altitudes are associated with lower obesity rates in the US and other countries, including Spain and Tibet.
-Colorado, the highest-altitude US state, has the lowest obesity incidence.
-County-level obesity data in the US reveals clear patterns in the Rockies, Sierra Mountains, and Appalachians.
-"Altitude anorexia" causes sudden weight loss in individuals relocating to high-altitude areas.
-Similar weight loss effect is observed in lab rats moved to higher-altitude labs.
-Evidence suggests a relationship between altitude and lower diabetes rates, independent of variables like age and BMI.
-Oxygen and carbon dioxide variations with elevation alone do not explain the altitude-weight relationship.
-Submarines with elevated CO2 levels do not consistently lead to weight gain, refuting atmospheric explanations.</code></pre>
This paper did a pretty poor job of controlling for cultural factors IMO. I would think there are significant differences in local base culture between locations. E.g. maybe if you are assigned to Colorado Springs there is more of a local focus on outdoor activities that leads to improved fitness, vs if you were closer to sea level in the Mojave desert where its simply too hot to be so active outdoors outside of forced marching.
From extensively researching the hpa-axis space my educated guess of what is going on:<p>At higher altitude you have higher levels of vitamin D, that in turn downregulates 21-Hydroxylase which means higher CRH is needed for the same levels of cortisol. The higher CRH means higher levels of Leptin, NPY, and Gastrin meaning less hunger and lower obesity rates.<p>This is presumably the same reasons why you gain weight all fall for winter/spring babies and lose it in the spring/summer. Just so happens at high altitudes you get more sun, more vitamin D.
I thought it was very well known that higher elevation results in reduced appetite.<p>I certainly have not been interested in eating whenever I've been above 5000m
higher altitude means less oxygen, means you need to inhale/exhale more to get the proper amount of oxygen, and also faster heart rate. Is it possible the metabolism of people at higher altitudes burn more calories just trying to get the same amount of oxygen?
This tracks with my anecdotal experience being from Colorado<p><a href="https://www.axios.com/local/denver/2021/09/20/colorados-obesity-rates-lowest-nationwide" rel="nofollow">https://www.axios.com/local/denver/2021/09/20/colorados-obes...</a>
Thermodynamics is a prime suspect. Higher equals colder. The increased cost of temperature regulation would account for some extra fuel burning. The data should be available to separate the effects.