Researchers at Stanford University gathered smartphone data on 68 million days of physical activity from 717,527 individuals around the world. Accelerometry features automatically detected and counted their steps.
The study, focused on 46 countries and designed to gain insight into exercise levels and their relationship to obesity, combined daily step information with obesity metrics.
An average Swiss resident clocked up 5,512 steps per day, ranking it 10th, and 9% above the global average. On obesity Switzerland came in 9th lowest.
As expected obesity levels declined with increased exercise. Chinese, the least obese, were the second biggest movers taking 6,189 steps a day.
Less expected was the discovery that average levels of obesity rise more when exercise levels vary greatly within a population, something the researchers named exercise inequality. Scott Delp, one of the team, said: “If you think about some people in a country as ‘activity rich’ and others as ‘activity poor,’ the size of the gap between them is a strong indicator of obesity levels in that society.”
An example of this is the difference between Britons and Swiss. An average UK resident walked roughly the same distance (5,444 steps) as an average Swiss one (5,512 steps), however UK obesity is 38% above the average while Swiss obesity is 36% below it.
There is however a marked difference in exercise inequality. The UK is ranked the 11th most unequal while Switzerland is ranked the 16th most equal. The UK is in the top quartile for exercise inequality while Switzerland is almost in the lowest third.
More walkable cities, such as New York and Boston, have lower exercise inequality than car-based cities, like the large centres in Texas. It seems that even the exercise-shy residents of New York prefer to walk than sit in traffic and chase hard-to-find car parks, sorting out the waistlines of those most likely to neglect them.
Saudi Arabia has the highest exercise inequality and the second highest obesity. At the other end, Hong Kong has the lowest exercise inequality and the third lowest obesity.
Overall exercise inequality correlated closely with activity-levels differences between men and women. In Saudi Arabia women walk far less than men. In Hong Kong everyone is out and about.
One thing the study doesn’t explain is why despite walking 18% further than women, men suffer higher rates of obesity. In Switzerland an average man walks 13% more steps than a woman yet is far more likely to be obese. A study funded by the Gates foundation estimates that 57% of Swiss men over 20 are obese or overweight. The same percentage for Swiss women is far lower at 16%. It seems Switzerland’s women are better at avoiding obesity despite moving less. Could it be the lady-sized meals, a phenomenon explained here by writer Diccon Bewes?
So what are the takeaways?
The way societies view gender and design their cities have an impact on health.
So if you’re hopping out for dinner, make sure you walk, take your partner, and order two lady-sized meals.
Link to study (in English)
Data source: Tim Althoff, Rok Sosic, Jennifer L. Hicks, Abby C. King, Scott L. Delp, Jure Leskovec. “Large-scale physical activity data reveal worldwide activity inequality.” Nature 547.7663 (2017).