High altitude does appear to offer some measurable health benefits, particularly for heart health and metabolic function. But the picture is more complicated than a simple yes or no. The advantages depend heavily on how high you go, how long you stay, and how your body adapts. Below about 5,000 meters (roughly 16,400 feet), the benefits tend to outweigh the risks for healthy people. Above that threshold, the downsides stack up fast.
Lower Heart Disease and Stroke Risk
The most striking evidence for high altitude’s benefits comes from cardiovascular health. A large Swiss study published in Circulation tracked tens of thousands of deaths and found that coronary heart disease mortality dropped by 22% for every 1,000 meters of elevation gain in a person’s place of residence. Stroke mortality dropped by 12% per 1,000 meters. These numbers held up after adjusting for factors like income, air pollution, and climate. The protective effect was stronger in men than in women.
The likely explanation is that living with slightly less oxygen forces the cardiovascular system to become more efficient over time. Blood vessels develop more branches, the heart adapts to pump blood more effectively, and the body gets better at extracting oxygen from each breath. These are chronic adaptations that build over years of residence, not something a weekend ski trip will produce.
Your Body Makes More Oxygen-Carrying Cells
When you move to higher elevation, your kidneys detect the drop in blood oxygen levels and ramp up production of a hormone that tells your bone marrow to make more red blood cells. This response kicks in within hours, and measurable increases in total red blood cell volume appear within the first one to two weeks. Studies on athletes living at altitude show gains of 3 to 5% in total hemoglobin mass after just one to three weeks of exposure.
More red blood cells means your blood can carry more oxygen per heartbeat. This is why endurance athletes train at altitude, and it’s also why long-term residents at moderate elevations tend to have robust oxygen delivery systems. During the first phase of acclimatization, your body also increases breathing rate and heart rate to compensate for thinner air. Over weeks and months, these emergency measures settle down as the deeper adaptations take hold.
Metabolism and Weight Loss
Altitude has a surprisingly strong effect on metabolism. Your basal metabolic rate, the number of calories your body burns at rest, increases by 6 to 27% in the first several days after arriving at elevation, with the size of the increase proportional to how high you go. At about 3,650 meters (12,000 feet), the bump is around 6%. At 4,300 meters (14,100 feet), it can reach 27%.
At the same time, appetite drops. In one study, 20 obese men spent seven days at a research station at 2,650 meters. They were allowed to eat whatever they wanted and limited their activity to slow walks. By the end of the week, they had lost an average of 1.5 kilograms (about 3.3 pounds), largely because their caloric intake dropped by roughly 734 calories per day while their metabolic rate went up. The appetite suppression appears driven by increased levels of leptin, a hormone that signals fullness. Low oxygen triggers cells to produce more leptin, and the effect is more pronounced at altitude than during comparable weight loss at sea level.
Below 5,000 meters, appetite tends to recover after the first few days as your body acclimates. At extreme altitudes, the appetite loss becomes persistent and can lead to dangerous muscle wasting, which is one of the reasons mountaineers lose so much weight on Himalayan expeditions.
Life Expectancy: A Mixed Picture
A national analysis of U.S. counties found that people living above 1,500 meters had longer life expectancies than those near sea level, by 1.2 to 3.6 years for men and 0.5 to 2.5 years for women. However, the same study concluded that the net effect on overall life expectancy was essentially neutral, because the cardiovascular benefits were offset by higher rates of certain other causes of death, including respiratory conditions like COPD.
This makes sense when you consider that the same low-oxygen environment that strengthens your heart also puts chronic stress on your lungs. People with pre-existing lung conditions often do worse at elevation. The relationship between altitude and cancer is still being studied, but increased cosmic radiation is a real factor: you receive more radiation from space at higher elevations, though the average annual dose in the U.S. from cosmic sources is still relatively small at 0.34 millisieverts per year.
Sleep Gets Worse Before It Gets Better
One consistent downside of altitude is disrupted sleep, especially in the first days and weeks. People traveling to high elevations frequently report insomnia, frequent awakenings, and a sensation of suffocation during the night. The root cause is that your body’s oxygen levels drop significantly during sleep at altitude. At around 4,500 meters, average blood oxygen saturation during sleep falls to about 80%, compared to the normal 95% or higher at sea level. At 5,500 meters, it can drop to 70%.
The disruption comes from a pattern called periodic breathing, where your brain alternates between rapid breathing and brief pauses. This starts appearing above about 2,000 meters and becomes nearly universal above 4,000 meters. Most people acclimatize over one to three weeks at moderate altitudes, and sleep quality gradually improves, though it rarely returns to sea-level normal for as long as you remain at elevation.
Altitude Sickness Is Common
The most immediate risk of going to altitude is acute mountain sickness, which affects about 25% of visitors sleeping above 2,450 meters (8,000 feet) in Colorado. If you fly directly to elevations above 3,400 meters (11,150 feet), the rate climbs to nearly 50%. The symptoms feel like a hangover: headache is the hallmark, often accompanied by nausea, dizziness, fatigue, and loss of appetite.
For most people, acute mountain sickness is unpleasant but self-limiting. It resolves within a day or two as the body adjusts. The standard prevention advice is to ascend gradually, giving your body time to acclimatize at each new elevation before climbing higher. Sleeping elevation matters more than the height you reach during the day.
Where the Benefits Peak
The research suggests a sweet spot for health benefits at moderate altitude, roughly 1,500 to 2,500 meters (about 5,000 to 8,200 feet). This range is high enough to trigger meaningful cardiovascular and metabolic adaptations but low enough that most people acclimatize fully without lasting side effects. Many of the world’s famously long-lived mountain communities, from parts of the Andes to regions of central Asia, sit in or near this band.
Cities like Denver (1,609 meters), Bogotá (2,640 meters), and Addis Ababa (2,355 meters) fall in this zone. Residents at these elevations experience the chronic, mild oxygen challenge that appears to keep the cardiovascular system tuned up without the sleep disruption, appetite loss, and lung stress that become problems at higher elevations. If you’re considering a move or an extended stay at altitude for health reasons, this moderate range is where the evidence is strongest and the tradeoffs are smallest.