High Altitude, Low Obesity?

04/17/2014 05:01 pm ET | Updated Apr 18, 2014
Ascent Xmedia via Getty Images

By Morgan Jones

Breathing the fresh mountain air might not just be good for the psyche; that altitude may also be good for the waistline.

A new study, which focused on US military service members, compared overweight service members in high altitudes and low altitudes.

The study found that the overweight service members living in high altitudes were less likely to become obese than their low-land counterparts.

According to the authors of this new study, which was led by Air Force Captain Jameson D. Voss, MD, MPA, of the U.S. Air Force School of Aerospace Medicine at Wright Patterson Air Force Base in Ohio, obesity and excess weight have become an increasing problem in the US military, despite programs like free health care, high levels of physical activity and weight regulations.

Capt. Voss and team wanted to examine if living at high altitudes could be tied to risk for obesity among those who were overweight, and thus considered to be at a higher risk of becoming obese.

The researchers observed all outpatient hospital or healthcare medical visits between January 2006 and December 2012 by enlisted US service members in the US Army or Air Force stationed in the US.

This study focused on overweight, but not obese, service members, as determined by their body mass index (BMI). BMI is a ratio of weight to height that determines healthy body mass. For this study, the researchers looked at service members who had a BMI of at least 25, but under 30 — scores that fall into the "overweight" zone.

In total, 98,009 service members were identified — the vast majority of whom were men — and followed for an average of 3.2 years. During this time, the researchers noted when participants had a change in BMI that would categorize them as obese or when a diagnosis of obesity occurred.

Capt. Voss and team compared results between those who were assigned a post at a high altitude (higher than 1.96 kilometers above sea level) versus those who were assigned to a post at a low altitude (below 0.98 kilometers above sea level).

The researchers found that those stationed at a high altitude were 41 percent less likely to become obese than those stationed at a low altitude. The study authors concluded that "[H]igh altitude residence predicts lower rates of new obesity diagnoses among overweight service members in the U.S. Army and Air Force."

"This is a very interesting study. Although it doesn't answer why people are less likely to become obese at high altitudes, it does attest to the healthy influence of mountain air," said Sarah Samaan, MD, cardiologist and physician partner at the Baylor Heart Hospital in Plano, Texas.

"Having lived in New Mexico, and done some of my training there, I know that a high altitude lifestyle tends to be one that celebrates an active outdoor lifestyle," Dr. Samaan told dailyRx News. "People who live at altitude often have easier access to hiking and biking trails than city or suburban dwellers. And while winter may be a time to huddle indoors in the 'burbs, for those at altitude, it often means more exciting winter sports like skiing and snowboarding. The lifestyle often extends to a fresher and cleaner diet, and fewer unhealthy habits."

She added, "As the authors point out, the lower oxygen levels at altitude may in fact have a direct effect upon appetite and metabolism, above and beyond any impact on lifestyle."

It is important to note that this study found an association, but not necessarily a causal relationship between altitude and a lower risk for obesity, and there were fewer service members stationed at high altitude to examine. Further research is needed to confirm these findings among a wider, civilian group and explore other factors that may be playing a role.

However, in a press release from the Armed Forces Health Surveillance Center, Capt. Voss explained that there are reasons why the military can be a good source for studies on residential health effects, including detailed records on service members.

“There are stronger implications for understanding the causal effect of location because service members do not freely choose where to live, but are administratively assigned to these locations,” said Capt. Voss.

This study was published April 16 in the journal PLoS One. Capt. Voss reported an intent to participate in developing a device related to altitude simulation for the US government. No other conflicts of interest were reported.

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