People who live at high altitudes are significantly less likely to be overweight or obese than people who live at low altitudes, according to researchers at the University of Navarra in Spain.
Low, medium and high
The researchers used data from a large, ongoing study of Spanish university graduates, called the SUN project. They tracked the progress of 9,302 graduates for an average period of eight-and-a-half years. None of the graduates were overweight or obese at the start of the study.
Based on the graduates’ postcodes and data from the Spanish National Cartographic Institute, they divided the people into three groups:
- Low: people living less than 124m above sea level
- Medium: people living between 124 and 456m above sea level, and
- High: people living higher than 456m above sea level.
The researchers also took into account the length of time each participant had been living in his or her city. “In Spain, the mobility of the people is lower than in other countries,” Dr Maira Bes-Rastrollo told BootsWebMD in an email. “We assumed that they would stay at the same location.”
Better to live higher up
During the follow-up period, 2,099 people became overweight or obese. In their analysis, the researchers took into account a number of factors that could have affected the participants’ weight such as their age, the number of calories they consumed each day, and their physical activity. After accounting for these factors, they found that people in the high elevation group (456m above sea level) were 13% less likely to be overweight or obese compared with those in the low elevation group (less than 124m above sea level).
Although earlier studies have found a link between living at high altitudes and lower rates of obesity, this is the first time that these findings have been confirmed in a “free-living” population.
No one is sure why people who live at higher altitudes are less likely to be overweight or obese but one theory is that, at high altitudes, the body produces more appetite suppressing hormones than at lower altitudes.
The low oxygen levels at high altitudes can cause a condition called hypoxia, which is when the body’s tissues don’t get enough oxygen to meet their needs. Hypoxia is thought to stimulate leptin production.
In a news release, the researchers said: “While it might not be realistic to expect everyone to move further uphill to reduce obesity levels, it is encouraging to see this effect occurred at only 450m altitude. The results are in agreement with potential biological mechanisms that are caused by hypoxia.”
Published: May 08, 2015. By Clint Witchalls
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