As the altimeter rises, the scale needle declines. Just spending time in the mountains can melt away the pounds, at least according a study conducted by German researchers that was recently published in the journal Obesity.

Dr. Florian Lippl of Ludwig Maximilians University in Munich, Germany, and colleagues, found that obese people who spent a couple of weeks at a high altitude mountain facility managed to lose weight without dieting. In addition, the weight loss was sustained for a minimum of 4 weeks after their return to normal altitudes. Although prior research has shown that weight loss can be attained at high altitudes, the majority of these studies involved physically active hikers and athletes. The Munich researchers set out to determine if the same weight loss benefits could also be gained by relatively inactive individuals.

The study involved 20 obese male participants having an average weight of 230 pounds. First, the subjects were monitored for one week at low altitudes to examine what they ate, and how often they walked. Next, the participants were taken up in elevation to about 8,700 feet above sea level to an air-conditioned, mountain-based research facility where they spent two weeks. During the stay at the mountain location, no restrictions were placed on what the participants were allowed to eat; however, they were not allowed to take part in rigorous exercise. Once the subjects were brought down to normal altitude, the researchers continued to follow them for four weeks. According to Lippl, the study findings revealed that while at high altitude, the participants lost approximately 3.3 pounds on average. The amount of weight loss, although moderate, was statistically significant when compared to the weight of the subjects at the start of the study.

The researchers theorize that at least part of the part of the weight loss can be attributed to the effects of the thin air on both appetite and metabolism. While on the mountain, the appetites of the participants were curbed, which was noted by a average decrease in calorie intake of about 734 calories per day, while an increase in metabolism caused participants to burn more calories without exercising. Another factor is that an increase in levels of the hormone leptin was observed while the subjects were at high altitudes, and this hormone can have the effect of making an individual feel full. Previous studies have shown that human cells produce more leptin when placed in a low-oxygen environment, such as that associated with thin air.

Once back in their normal environment, the study participants tended to walk more, which likely helped them to keep off the extra pounds shed at high altitudes. According to Lippl, this may be attributed to their feeling more fit since they no longer faced the stress of the low-oxygen, mountain environment. Lippl said, "With a little humour, I tell my patients now, if they want to take holidays, they should think of mountain holidays [rather] than spending their holidays at the sea." But, don't run for your mountain retreat just yet. Further research will be necessary to confirm the study findings, and to determine what causes the high altitude weight loss effect.