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By Denise Mann

THURSDAY, Feb. 4, 2010 (Health.com) — Can a simple change in location help you shed pounds? Maybe, according to a new study that found that obese men lost a few pounds after spending just one week at high altitude, even though they didn't feel hungry or exercise more than usual.

What’s more, the weight stayed off for at least four weeks after the men returned to a lower elevation, according to the study, which was published today on the website of the journal Obesity.

“It’s a universal finding that people lose more weight at high altitudes," says Robert Roach, PhD, the research director of the Altitude Research Center at the University of Colorado in Denver. "The really new and exciting thing in this study was taking obese people to a high altitude and showing the same effect we have seen in non-obese people.”

Why the weight loss? While researchers aren’t certain, the lower oxygen at high altitudes has been shown to dampen appetites and increase metabolism.

In the study, 20 men who weighed an average of 232 pounds spent one week at roughly 8,700 feet above sea level, at a research station just below the summit of Germany’s tallest mountain. While at the research station, the men could eat and drink as much as they wanted and were only allowed to take slow walks around the facility, to prevent them from increasing their activity above normal levels.

The men lost three to four pounds each, on average, and kept the weight off for at least four weeks after they returned to low altitudes, according to the study, which was conducted by researchers at the University Hospital of the Ludwig-Maximilians-University in Munich, Germany.

The men all had metabolic syndrome, a constellation of risk factors (such as blood-sugar intolerance and high blood pressure, in addition to obesity) that are known to increase the risk of heart disease, stroke, and diabetes.

While on the mountain, the men's metabolism increased, they consumed fewer calories, and their blood-sugar levels and diastolic blood pressure (the bottom number in blood-pressure reading) improved. Their levels of leptin, a hormone known to suppress appetite, also increased at the high altitudes.

Next page: Results could pave way for new obesity treatments

That the weight stayed off for weeks after they returned was surprising, since in previous studies of weight loss among normal-weight individuals at high altitude, the weight has tended to come back when the people return from living or training at altitude.

"It's remarkable that the effects lasted after they returned from the mountain," says Roach. "Whatever it is that promotes weight loss at high altitudes may be more potent in heavy people because it provides a lasting effect."

However, the increase in leptin did not seem to play a role in the men’s ability to keep all or some of the weight off, according to the study.

“We don’t fully understand the mechanisms yet, but if there is a unique pathway that regulates appetite at high altitudes, it could pave the way for new treatments for obesity,” says Roach.

The study had several limitations. It was small, and it didn't include a control group (such as a similar group of men who were confined to a research center at a lower altitude). In addition, the fact that the men knew that the effect of altitude on their weight was being studied may have influenced their behavior and skewed the results.

“The new study is intriguing and suggests that we need to do a lot more research into the effects of high altitudes on our weight and our health,” says Richard Atkinson, MD, the director of the Obetech Obesity Research Center of Virginia Commonwealth University, in Richmond.

While once-a-month mountain climbing isn’t the most practical way to shed a few pounds, moving to a high-altitude city instead of a low-altitude city isn’t a bad idea—if you have a choice, says Dr. Atkinson. “If you're mildly obese, have metabolic syndrome, and have a choice of taking a job in either a high or low altitude, go to the high altitude,” says Dr. Atkinson. “It won't cause you to lose massive amounts of weight, but every little bit helps.”

Colorado has the lowest obesity rate in the U.S, and the altitude may be part of the reason, says Dr. Atkinson.