As you move up from sea level the pressure of the air around you goes down. Atmospheric pressure composed of all the gas molecules including oxygen falls with altitude to be only 30% of the sea level value at 29,000 feet, the height of the summit of Mount Everest. The blanket of air around the earth is actually pretty slim. Still it’s thick enough to burn up a lot of meteorites and space junk.
People living at high altitude happens in Tibet, and the Altiplano of the Andes mountain range of South America among other spots on earth. As you move to higher elevations the fall in the oxygen pressure you breath reduces the driving pressure for gas exchange in the lungs and this in turn produces a cascade of effects right down to the level of the mitochondria, the final destination of the oxygen for making energy. So those people living at high altitudes live with the constant stress of lower oxygen in their blood to deliver to the cells of their bodies.
A recent study report shows that one of the effects of this is a lower incidence of metabolic syndrome, lower blood sugar and cholesterol, and it causes you to eat less. (1) These Spanish scientists studied 260 university graduates over 20 years of age in Ecuador, 152 lived at sea level on the coast and 108 lived above 9000 feet in the Ecuadoran Altiplano.
They found that people living high had less high blood sugar and less high cholesterol. They had lower central obesity-waist circumference, but not body mass index (BMI). They also found that they ate less, on average 236 fewer calories a day. That might explain all the other associations. But they didn’t exercise any more. They were probably too tired. And the rate of high blood pressure actually was a little higher in the group living at high altitude.
Similar findings to these have been found in other observational studies.
So if somebody from Denver, Colorado (5280 feet, 1 mile high) says he is not as lazy and gluttonous as people living in other parts of the country and that’s why he’s not as fat, don’t believe him, he’s cheating.
1. Lopez-Pascual A, et al. Inverse Association Between Metabolic Syndrome and Altitude: A Cross-Sectional Study in an Adult Population of Ecuador. Frontiers in Endocrinology 2018; 9: 658. Published online 2018 Nov 12. doi: 10.3389/fendo.2018.00658