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It’s easy to think of obesity as an American problem because of how often we’re reminded of its prevalence, from the seemingly endless fast food joints and convenience stores on every major city block, to the discouraging government reports all over the Internet.
However, obesity is just as much of a worldwide issue—global rates have more than doubled since 1980; more than 1.9 billion adults were classified as overweight or obese in 2014, as well as more than 41 million children under the age of five.
In a world where people are getting heavier and heavier, understanding the root cause of obesity—and its link to life expectancy—have become paramount in the medical field. An untold number of studies have set out to figure that out, but given the amount of different subsets and populations to choose from across the world, it’s difficult to pin down overarching measurements and causes.
That was on the mind of a group of international researchers who hoped to combine the scores of studies to come up with more precise conclusions. The analysis, led by Dr. Emanuele Di Angelantonio from the University of Cambridge, brought together more than 500 investigators from about 250 institutions across the world who analyzed an immense amount of data from smaller studies whose participants totaled nearly 4 million people.
“We’ve been able to collate and harmonize all the data and to run similar analysis across all the different studies,” Di Angelantonio tells BTRtoday. “This is possibly the largest pool of data that has been published so far on body mass index (BMI) and mortality.”
According to Di Angelantonio, the main goal of the collaboration was to assess the connection between BMI—the main measurement to define obesity—and mortality in different parts of the world. The analysis originally took into account more than 11 million various study participants, but eliminated biases that skewed previous measurements, such as smokers and those with preexisting diseases.
“Those conditions can actually affect BMI,” Di Angelantonio says. “That causes a circle that makes it very hard to understand exactly what is causing what.”
Aside from being landmark in terms of bringing together such an enormous amount of data, the analysis also revealed interesting results.
“One of the striking findings of our study was that the risk of mortality was three times higher in men than in women,” Di Angelantonio explains. “That’s quite a new finding. These results can possibly be explained by previous studies’ findings, for example that men usually have a greater insulin resistance or a greater risk for diabetes than women.”
Di Angelantonio was also struck that the analysis revealed that there has been minimal difference in the association of obesity and mortality in different parts of the world. From North America to East Asia, it’s practically the same.
The comprehensive takeaway from the analysis is that as obesity rates grow worldwide, it’s important to know the kind of affect it can have on a given person’s life. The main drivers of obesity, diet and physical activity, remain the same, but DiAngelantonio also refers to Westernization—where people in non-Western countries are picking up more of a Western lifestyle—as another key cause.
“The obesity rates will continue to grow, and there have been many calls to reduce obesity,” he says. “It’s not an easy task, but a true public effort and true individual efforts can really help tackle this epidemic of obesity around the world.”