Tipping The Scales: How Obesity Influences Planetary Health

By Amanda Solliday

Posted June 26, 2012

When people think about environmental sustainability, they immediately focus on population. 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.

That's according to Professor Ian Roberts, co-author of a recent study from the London School of Hygiene and Tropical Medicine.

The obesity epidemic, it seems, is just as much of a burden on the planet as an exploding population.

Global Heavyweights

Not surprisingly, obesity rates vary widely across the globe. In North America, 73.9 percent of the population is overweight or obese. Compare that to 24.2 percent in Asia, which is the world's slimmest continent.

Using data on body mass index (BMI), height distributions and population counts, the researchers calculated total human biomass, biomass due to overweight (defined as BMI >25) and biomass due to obesity (BMI >30) for each country. A small number of countries were excluded from the analysis due to lack of available information.

A Huge Tragedy Of The Commons

Looking solely at food consumption, the group estimated the additional energy required for earth's expanding waistlines.

If global biomass increases so that all countries have the same BMI distribution as the United States, the energy required to sustain the additional heft would be roughly equivalent to the energy demands of 473 million extra people of healthy size.

But not all wealthy countries appear to have the same obesity problems as the United States.

"The Japanese example is quite strong. Average BMI (Body Mass Index) 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," asserts Roberts.

The Rise Of Car Culture

Going down the list of heaviest countries, you find that nations like Kuwait and Egypt are not far behind United States.

In a recent interview with NPR, Roberts theorized, "What's common between those is actually the price of gasoline is very low. So where gasoline is really cheap, we over-consume it, it's bad for the environment and actually because we should be using food energy for human movement. If we use gasoline for human movement, then we store the food energy and you know where we store it."

The researchers also point out that a rise in caloric demand means that more fossil fuels are used to produce and transport food. In the future, they plan to quantify how carbon emissions relate to overweight populations.