Last month,researchers affiliated with the World Health Organization and the London School of Hygiene and Tropical Medicine reported that,worldwide,peoples waistlines are expanding,with the total combined weight of human beings on Earth now exceeding 287 million tons. About 3.5 million tons of that global human biomass is due to obesity,a third of which exists in North America.
The study,however,did not address possible underlying causes of the ever-growing weight of nations.
But a group of groundbreaking new reports,being published online as a series today in The Lancet,suggest that voluntary physical inactivity,a practice once confined mostly to North America and parts of Europe,is spreading rapidly to the rest of the world and likely contributing materially to global gains in tonnage and declines in health.
Consider the findings of perhaps the most sobering of the new studies,which looked at the extent to which sedentary lifestyles are colonising the world.
Led by Pedro C Hallal,a professor at the Federal University of Pelotas in Brazil,researchers turned to a large body of data about activity that the WHO has been collecting in recent years. To gather data,the WHO provides questionnaires to people in various nations that ask,in effect,how much they exercise and otherwise move in their daily lives,an admittedly inexact way to measure activity (people misremember or,for cultural or other reasons,prevaricate). But its the best global information currently available.
The latest figures suggest that the worlds population has become disturbingly inactive. According to researchers calculations,31.1 per cent of the worlds adults,or about 1.5 billion people,are almost completely sedentary,meaning that they do not meet the minimum recommendation of 150 minutes of walking or other moderate activity per week,or about 20 minutes a day.
Teenagers are faring even worse. More than 80 per cent of young people ages 13 to 15 worldwide are not getting the hour a day of exercise recommended for their age group.
Unsurprisingly,North America and Europe lead the world in not exercising,with 43.3 percent of Americans and 34.8 percent of Europeans not reaching the low recommended threshold. But the world is catching up. More than 30 per cent of Russians are inactive nowadays; ditto in the Middle East; and about 27 per cent of Africans are sedentary.
Although in general,the richer the nation,the less active it is,the most sedentary nation on Earth is the tiny island of Malta,population 419,000,72 per cent of whom almost never voluntarily move around much.
The consequences for global and personal health are punishing and likely to grow more so,reports another first-of-its-kind study in the Lancet series. In it,the authors conclude that sitting around most of the day has become as deadly as smoking or obesity.
Specifically,using data from WHO and other large population studies worldwide,researchers determined that inactivity is linked to about 6 per cent of all instances of heart disease on Earth; 7 per cent of Type 2 diabetes cases; and 10 per cent of all breast and colon cancers,including among people who dont smoke and are of normal weight.
About 5.3 million people a year die from diseases tied to physical inactivity,the authors calculated.
By comparison,about 5.1 million die annually because of smoking,as an accompanying comment article points out.