High Altitudes May Lead to Weight Loss

Weight loss is a natural phenomenon for anyone who travels from sea level to extreme altitudes. The amount of weight lost depends on how high you go and how long you stay, and has always been thought to be temporary. In addition, high-altitude weight loss has always been associated with active people who spend time hiking and skiing in mountainous areas.

Now, a study published in the online journal Obesity suggests that even the average overweight person can lose a few pounds while vacationing in, say, the mountains of Colorado, or the Himalayas, and keep most of the weight off after coming back down. At least for one month.

German researchers took 20 grossly overweight, middle-aged men from their homes in Munich, where the airport elevation is less than 1,500 feet above sea level, to an elevation of about 8,700 feet on top of Germany's highest mountain, the Zugspitze. The men lived normally on the mountaintop for one week with no diet restrictions and no exercise other than walking around inside the research station. They lost an average of three and a half pounds during their stay.

At extremely high altitudes, significant weight loss is inevitable. The average person who manages the 29,000-foot climb up Mt. Everest, for example, will lose 20 percent of body weight on the trip. Some of that loss is due to an increase in resting metabolic rate and diminished appetite that occur at higher altitudes, as well as the obvious amount of work it takes to climb up and back. But the men who participated in the German study did no climbing. They were transported to and from the mountaintop and engaged in very little physical activity, yet they burned more calories while they were up there than they normally burn at home.

The most interesting aspect of this study is that once the men returned to a lower altitude, they continued to burn more calories than normal. Just one week on the mountaintop appeared to kick-start their metabolism to the degree that, when measured one month later, they kept off more than half the weight they had lost and were able to exercise more effectively than at the beginning of the study.

Climbing mountains for sport, or just routinely visiting high-altitude areas may turn out to be effective weight loss strategies. Living permanently at a higher altitude doesn't necessarily have the same effect, however, because people who are native to higher altitude regions appear to be "pre-acclimated." They appear to respond to the environment and its inherent lack of oxygen by developing greater lung volume to compensate. For instance, native Himalayans who live in the mountains have a much easier time climbing Everest than non-natives, and use up many fewer calories getting to the top and back. Further research is necessary to determine if permanent weight loss can be achieved and maintained at various altitudes but, for now, visiting a mountain resort area appears to be more effective than living in one.


Obesity (4 February 2010)

Wired: Altitude Causes Weight Loss Without Exercise

The University of Utah