This topic caught my attention as I have been staying in San Cristobal de las Casas in the Highlands of Southern Mexico for two months now and have noticed a weight loss in spite of feeling like I am eating like a horse.  I seem to have so much more need for food than I did living in the south west of England at near sea level.  At the same time I have noticed that my appetite is less, I eat because I really I feel I need to and it seems to be more considered choices of food.  I will be writing more about the food in this area..it is quite a inspiration, very healthy and also suitable for this environment. Meanwhile I am sharing this intel about weight loss at high altitude.  It seems that the increase in red blood cells caused by the drop in oxygen, reduces levels of the hunger hormone leptin.  At the same time, our metabolism needs more fuel.  And there is a residual effect after returning to lower lying land.  It has made me think about the possibilities of organising retreats in this kind of area,  It also acts as  a kind of athletic training because the body has to adapt to less oxygen.

Dreams can become more vivid becasue the change in oxygen levels affects the sleeping cycles making them shorter, and you are more likely to be wakeful in the night.

Of course at very high altitudes there are formidable challenges.  I am talking here from the experience of living at a very liveable 2.200 metres above sea level.

http://www.huffingtonpost.com/2014/03/27/high-altitude-weight-loss_n_4980659.html

“A 2013 study found that Americans who live at sea-level are four to five times more likely to be obese as those who live in the highest altitude communities in Colorado — even after they controlled for other factors like exercise level, socioeconomic status and family history.

What’s more, a totally unrelated 2010 study showed that even if you don’t live in a high-altitude area, simply going to one could lead to weight loss.

Was their weight loss the result of a quickened metabolism? Yes, but that doesn’t tell the whole story. As Wired reported, in addition to getting a revved up metabolism, the men experienced hunger and satiety differently up on high:
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.

According to the research, the men ate an average of 730 fewer calories per day while up in the air and that shift in appetite remained after they came back down.
“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,” altitude expert and Massachusetts General Hospital anesthesiologist Kay Leissner told Wired at the time of the study’s publication.

There’s no denying that the low-oxygen environment of high altitude has some effect: As LiveScience points out, in vitro studies show that human cells produce more leptin (the hormone that helps you feel fuller) when exposed to air that replicates high-altitude.”

http://www.womenshealthmag.com/weight-loss/weight-and-altitude

“At higher elevations, you inhale less oxygen per breath. Your body compensates for the decreased O2 by producing more red blood cells, which carry oxygen to your tissues. Previous research suggests the surge in red blood cells may cause your body to churn out more appetite-regulating hormones. The result: You eat less and keep your weight in check.”
http://www.livescience.com/6051-obese-people-lose-weight-high-altitudes.html

“Interestingly, the participants maintained their reduced weight after they had returned to normal altitude and stayed there for four weeks, a finding the researchers did not expect.”

http://www.wired.com/2010/02/high-altitude-weight-loss/

“JUST A WEEK at high altitudes can cause sustained weight loss, suggesting that a mountain retreat could be a viable strategy for slimming down.
Overweight, sedentary people who spent a week at an elevation of 8,700 feet lost weight while eating as much as they wanted and doing no exercise. A month after they came back down, they had kept two-thirds of those pounds off. The results appear in the Feb. 4 Obesity.
“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,” said Massachusetts General Hospital anesthesiologist Kay Leissner, who studies high altitude physiology, but was not involved in the study.

Since a 1957 study, scientists have known that animals lose weight at high altitudes. Mountaineers also shed pounds during expeditions to 12,000 feet or more, though the exertion of climbing a mountain clearly played a role.
But the obese are more likely to suffer severe altitude sickness, in which low oxygen pressure causes dizziness, nausea and more serious problems like edema or heart attacks, Leissner said.
So a  team at Ludwig-Maximilians University in Munich wanted to see if the pounds also melted away with a safer, sedentary stay at somewhat lower altitude.
The scientists ferried 20 overweight, middle-aged men by train and cable car to a research station perched 1,000 feet below the peak of Germany’s highest mountain, Zugspitze. During the week-long stay, the men could eat and drink as much as they liked and were forbidden from any exercise other than leisurely strolls. The team measured the men’s weight, metabolic rate, levels of hunger and satiety hormones before, during, and after their mountain retreat.
After a week up high, the subjects lost an average of 3 pounds.  A month later, they were still 2 pounds lighter. The sceintists’ data showed this was likely because they ate about 730 calories less at high altitudes than they did at normal elevations. 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”