Researchers at the London School of Hygiene and Tropical Medicine have found that the human population is 17 million tons overweight as a whole, according to a study published June 18 in the journal BMC Public Health.
The energy requirements needed to sustain this excess weight is the equivalent to that of 473 million adults, researchers noted.
"When people think about environmental sustainability, they immediately focus on population," Ian Roberts, one of the authors of the paper and a professor of epidemiology & public heath at the London School, told BBC News. "Actually, when it comes down to it—it's not how many mouths there are to feed, it's how much flesh there is on the planet."
Fatness is part of the issue "exceeding our planetary limits," Roberts concluded.
The team also estimated the total weight of people on the planet and found that North America had the highest average weight. While only 6 percent of the global population lives in North America, the continent accounts for 34 percent of the world's biomass, because more than a third of its residents are considered obese. In comparison, 61 percent of the world population lives in Asia, but it only accounts for 13 percent of the Earth's biomass.
If the body mass index (BMI) distribution of the United States was replicated on a global scale, it would equate to the addition of nearly one billion average-size people on the planet.
Roberts explained that stressing the obesity of individuals or groups is unhelpful. "...[I]t fosters a them and us ideal—when actually we're all getting fatter, ” Roberts told BBC News.
Countries like Eritrea, Vietnam and Ethiopia ranked very low on the obesity scale, but researchers argue it is not a factor of poverty, pointing to Japan as a prime example. According to Roberts, the country could be a model for others.
"The Japanese example is quite strong. Average BMI in USA in 2005 was 28.7. In Japan, it was 22. You can be lean without being really poor, and Japan seems to have pulled that off."
One culprit of obesity: the automobile. "One of the most important determinants of average body mass index is motor vehicle gas consumption per capita," Roberts said. "So, it is no surprise to see many of the Arab countries in the list—people eat but they move very little because they drive everywhere."