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Comment by kjkjadksj | Hacker News Reader

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.

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They also seem not to have controlled for terrain. High altitude locations are, generally, more mountainous. That means, even without any increase in perceived exercise, you are doing more vertical as you go about your day.

I grew up in the mountains. When I went to basic training I was all set for serious hiking. But basic training wasn't in the mountains. I was shocked at house easy long marches were when there were no real hills.

They also seem to have overlooked D3 levels. Colorado in particular, has much higher UV levels and people tend to have higher D3 levels.

A surprising number of calories are spent repairing skin damage. Increased uv exposure at altitude probably makes a difference, but probably doesn't help skin cancer rates.

This was my experience when I moved to CO. On the east coast I had to drive to running trails and cycling routes by my house had no shoulders and a lot of traffic. In CO I had access to 120 miles of trails from my backyard and the roads had either dedicated bike lanes or wide shoulders.

Add in a walkable grocery store and I was a lot more active in CO than I was on the east coast.

That sounds awesome! Where in CO was this?

Or if you prefer, is that the case for anywhere outside Boulder?

This was outside of Boulder, in Westminster, just west of 25 on 136th.

Exactly my thought. High elevation could mean proximity to cool hikes, skiing, mountain biking, etc, while low elevation could equal corn fields and drinking beer while fishing on a lake.

... and please don't respond with counterpoint examples. Yes, I'm aware high elevation can be flat/boring and low elevation can be exciting and full of outdoor adventure.

There is a condition called “altitude anorexia”(1) where individuals who move to a high-altitude location sometimes lose a lot of weight all at once - see also (2), (3), and weight loss results(4). This effect also seems to apply to lab rats who are moved to labs at higher altitudes.(5)

(1)https://pubmed.ncbi.nlm.nih.gov/18284032/ (2)https://www.wired.com/2010/02/high-altitude-weight-loss/ (3)https://www.liebertpub.com/doi/abs/10.1089/15270290432296375... (4)https://academic.oup.com/icb/article/46/1/25/661337?login=fa... (5)https://jn.nutrition.org/

I live in Colorado. A large chunk of the state intentionally moved here specifically due to outdoor recreation opportunities and had kids who also do these (skiing, hiking, climbing, biking, etc). We also have ample public land and parks/green space/trails in which to recreate - which states like Texas lack.

The military may not have the same choice on where to move, but when they get here there's opportunities and communities to be active.

This subject about CO being fit came up recently when Robert Lustig was on the Huberman podcast:

https://www.youtube.com/watch?v=n28W4AmvMDE&t=7000s

A chart showing BMI vs altitude could help cut through individual bases differences. If there is a trend downward it would show a dose-response effect. I didn't find such a chart in the paper. Instead they have a chart showing how many data points were available by altitude.

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