I can confirm that venturing well above sea level can make you sick. I, like many other travellers that have visited South America and the Himalayas, can vouch for the shortness of breath, nausea and pounding headaches. As your body fights to acclimatise, your heart race increases to supply more oxygenated blood to tissues, making exercise more difficult. These are just some of the most common physiological changes altitude has to our bodies. From what I have learned, you can be the fittest person in the world but can still be affected by altitude sickness. And you won’t know until you experience it yourself.
If you’re born in Tibet, consider yourself lucky. As reported by BBC News, the Nature journal has announced that a variant of the EPAS-1 gene, that affects blood oxygen, is commonly present in Tibetans – many of whom live at altitudes of 4,000m year-round.
But could living well above sea level provide some health benefit to the average person that doesn’t possess this altitude gene?
Reachers and alpinests have observed weight loss in the mountains. According to a 2013 study, Americans residing at sea level are four to five times more likely to be obese than those who live in high altitude communities in Colorado, after consideration of factors including exercise level, socioeconomic status and family history.
Another study conducted three years prior to this one, demonstrated that visiting a high-altitude area could lead to weight loss. A group of 20 obese and sedentary men were taken to an elevation of 8,700 feet (over 3,500 feet higher than Denver) and were allowed to eat plentifully but were prohibited from exercising, apart from leisurely strolling. After one week, they had lost an average of three pounds. After the men returned to their communities at low altitude a month later, the group maintained a weight loss average of two pounds.
Although the weight loss can be attributed to a faster metabolism, there’s more to it than that. Additionally, as Wired reported, the men experienced hunger and fullness differently at high altitude:
They may have felt less hungry, in part, because levels of leptin, the satiety hormone, surged during the stay, while grehlin, the hunger hormone, remained unchanged. Their metabolic rate also spiked, meaning they burned more calories than they usually did.
The men ate an average of 730 fewer calories per day while at high altitude and maintained their shift in appetite after they came back down.
Altitude expert and Massachusetts General Hospital anesthesiologist Kay Leissner told Wired at the time of the study’s publication, “What is nice about this paper, is that it clearly demonstrates that there’s a lasting effect of decreased caloric intake, that people eat less even a month after they come out of high altitude,”
High altitude is synonymous with low-oxygen and there’s no denying that it doesn’t effect our bodies. According to LiveScience, in vitro research has revealed that human cells produce more leptin (the hormone that helps you feel fuller) when exposed to air that replicates high-altitude.
It is unknown whether the men that took part in the study lost the weight from muscle, fat or water loss.
Undoubtedly, there are easier and safer ways to shed three pounds.