It’s no secret that people living in high elevation areas such as Summit County seem to be healthier than the general population. But aside from the active lifestyles of many people who choose to live in the mountains, could there be other effects from living at high altitude that result in healthier outcomes?
Several studies have been conducted to examine the association between living at high altitude and weight loss. The overall findings suggest simply ascending to a higher altitude generally results in a reduction of weight. Whether this is due to relative low pressure hypoxia or increased physical activity is another question examined by researchers. Overall, a higher energy expenditure and decreased appetite have both been seen in those living at higher altitudes. One study found that those living below 500 m elevation on average had a 4.6 times higher risk of obesity compared to those living above 3000 m while controlling for differences in exercise, diet, and lifestyle.
Leptin is a hormone produced by the body that results in suppression of hunger. When our bodies secrete more leptin our hunger decreases. Multiple studies have shown that when people not acclimated to altitude are brought to higher elevation, leptin increases and appetite decreases. One such study took ten obese males to altitude and allowed them to eat as much as they would like and also did not allow them to exercise more than their regular amount during the study. After one week the study found the males consumed on average 730 calories less than what they usually ate at lower altitude. This resulted in a 3 pound weight loss over one week, and on average, they kept two pounds off after returning to their base altitude a month after the one week study was completed.
Leptin levels were increased for a time after returning to lower elevation and appetite remained lower than their baseline.
A follow-up study looked to determine exactly what factor of altitude causes this increase in leptin and used a hypobaric chamber to simulate a hypoxic environment similar to Mt. Everest. Subjects in this experiment lived in low oxygen conditions for 40 days and had an average of 16.7 pounds of weight loss and consumed 1,347 fewer calories. This study helped to suggest hypoxia as the driving factor for increases in leptin at altitude, and also showed an increased effect with the higher elevations.
Another possible factor leading to higher rates of weight loss at altitude could be linked to an increase in basal metabolic rate. Basal metabolic rate, or BMR, is the amount of energy or calories humans burn each day without accounting for exercise or general physical activity. In the same study that measured appetite and leptin levels in obese men brought to altitude for one week, BMR was also measured. These measurements showed an increased BMR at the end of one week at altitude and a return to baseline BMR two weeks after returning to lower altitude. This means that people tend to burn more calories just by being at a higher altitude, even without increasing exercise. This increased burning of calories paired with decreased appetite are likely the main driving forces between the weight loss seen in those newly introduced to altitude and lower weights and BMI’s seen in those that have lived at altitude for a long time.
With these findings of weight loss and overall decreased appetite when coming to altitude, it is important for visitors from low altitudes to be aware of these changes and plan appropriately. First of all, in order to avoid unintended weight loss, those new to the mountains should be aware of just how much they are eating. Apps such as MyFitnessPal are great for tracking your calories and can even factor in exercise such as hiking and skiing that may be causing you to burn extra calories. Based on your BMR and exercise, you can see just how many calories you should be eating to maintain your current weight. It is also essential to be aware of the kinds of food you are eating. In the studies showing decreased appetite, it was also shown that study subjects had a decreased likelihood of choosing carbs in their diet. Carbohydrates are an excellent source of energy and should be a main staple of the diet for anyone coming to altitude, especially if they plan to partake in any of the great outdoor activities places like Summit County have to offer. Good examples of healthy carbs include fruits, vegetables, nuts, and whole grains like quinoa, oats, and brown rice.
Ultimately, ascent to higher altitudes has been shown to cause a decrease in appetite, increase in basal metabolic rate, and an overall decrease in body weight. Some of these factors return to closer to baseline after acclimatization, but this can take weeks to months depending on the person. Anyone who is traveling to higher altitudes or who has recently moved to a higher altitude should take good notice of their general nutrition and calorie intake to make sure they are giving their body the fuel it needs to succeed in these unique conditions.
Mitch Tiedke is a physician assistant student at the Red Rocks PA Program in Arvada, Colorado. He grew up in Oak Grove, Minnesota and achieved his undergraduate degree in Genetics, Cell Biology, and Development, with a minor in Public Health from the University of Minnesota-Twin Cities. He has previously worked as a personal care assistant for developmentally delayed adults and as a nursing assistant on a pediatric oncology, GI, and med/surg inpatient unit. In his free time he enjoys hiking, snowboarding, biking, and movies.
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