HILL AIR FORCE BASE, Utah — With an elevation of nearly 5,000 feet, the air is thinner at Hill Air Force Base and apparently, so are the airmen.
That's what new study released by PLOS ONE concludes after its authors examined the correlation between obesity and altitude among enlisted Air Force and Army personnel. PLOS ONE is an open access, peer-reviewed scientific journal published by the Public Library of Science.
Between January 2006 and December 2012, authors of the study examined more than 98,000 enlisted airmen and soldiers with body mass indices between 25 and 30, a median of 3.2 years of military service and who moved between high elevation duty stations like Hill Air Force Base and bases less than a half mile above sea level.
The study showed that airmen and soldiers who were already overweight were less likely to become obese if they were assigned to a high-altitude duty station — more specifically, they had a 41 percent lower risk of obesity than those living at low altitudes.
The study took into account the body mass index at the time of subject's enlistment, their sex and several other factors.
Lead author of the study, Dr. Jameson D. Voss, a consultant with the United States Air Force School of Aerospace Medicine, said the study suggests that moving into a higher altitude would protect an overweight person from becoming obese.
"This provides the first evidence of a longitudinal association between living at high altitude and long-term obesity protection," the study says.
Researchers aren't 100 percent clear on way high altitude curbs obesity risk, but hypothesize in the study that hypoxia and leptin play a part.
Hypoxia is a condition where the body or a region of the body is deprived of adequate oxygen supply. Research shows that therapeutic levels of hypoxia, like what can be found in high altitudes can reduce appetite and body fat.
Leptin, a a hormone made by fat cells which regulates the amount of fat stored in the body and helps suppress appetite. The study says serum leptin levels been have found to rise at high altitudes.
With troops spending much of the past decade in the high altitude regions of Afghanistan, elevation has been somewhat of an important topic in military circles.
In 2012, the Air Force began instituting an "altitude adjustment" for it physical fitness tests. Airmen living in high altitude areas are given more time to complete the Air Force's 1/5-mile run test.
The adjustment was initiated after a study at the Air Force Academy's Human Performance Laboratory indicated there was a difference in cardiorespiratory performance between high altitude areas and sea level.