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U.S. Population Fatness Threatens Global Environmental Sustainability

Posted Aug 08 2012 9:44am

We all know that the world’s ever growing population is putting a massive strain on the Earth’s finite resources.  After all, the world’s current human population is 7 billion and is expected to rise to between 8.9 and 10.5 billion by the year 2050.  Compare this to the 350 million people on the planet at the end of the Great Famine and the Black Death of 1350 and it becomes truly striking how many more mouths have to be fed, shelters need to be built, and fresh water must be retrieved (among numerous other resources) today versus less than 700 hundred years ago.  Homo Sapiens have been around for hundreds of thousands of years, but there have simply never been so many people.


Those figures are nothing new and what I’ve just written certainly isn’t groundbreaking.  However, what might foster a new perspective on population growth is that it’s not just the number of humans that matter when it comes to environmental sustainability, it’s how much we all weigh.  Recent research published in BioMed Central’s open access journal BMC Public Health has estimated total mass of the human population, defined its distribution by region, and the proportion of this biomass due to those who are overweight and obese.

Increased mass equates to higher energy requirements simply because it takes more energy to move a heavy body and more food to sustain that size.  Even while resting, a bigger body needs more calories than a smaller one. 

Employing data from the United Nations and World Health Organization, researchers from the London School of Hygiene and Tropical Medicine have concluded that the adult human population weights over 316 million tons, of which 7 million tons are due to the overweight and 4 million tons to the obese. The average body mass globally was 137 pounds, yet the average body mass in the United Statues was 178 pounds. This is quite an increase in weight! Startlingly, the United States has 6% of the world’s population but 34% of the world’s biomass due to obesity.  In contrast, Asia has 61% of the world’s population but only 13% of the world’s biomass due to obesity.   

If all countries had the same average BMI as the United States, the total human biomass would increase by 64 million tons, which is the equivalent of the addition of 935 million people of world average body mass.  This study makes it clear that we need to begin thinking about population growth and population fatness if we are to effectively address this impending pickle of too few resources on a planet that cannot cater to the growing demands we place on it.

Foods that promote fatness tend to be the same foods that are most environmentally unsustainable.  Vegans, on average, are slimmer than omnivores and meat requires much more energy to produce than plant foods.  Professor Vaclav Smil of the University of Manitoba, Canada conducted research showing that beef cattle raised on factory farms convert as little as 2.5% of their gross feed energy into food for human consumption.  So, being fat raises resource requirements per person as does the production of foods that incline individuals towards obesity. Given that most livestock are fed human-edible grains that could be used to feed hungry people (there are currently 1 billion people lacking enough food to eat), this is especially damning.  Livestock production exceeds 21 billion animals each year and when the simple math is done, this means that there are more than three and a half times as many animals killed for human consumption than there are humans on the planet. A report by the Food and Agriculture Organization of the United Nations has shown that livestock are now consuming six times more food than dinosaurs ever did.1

So, not only is being overweight or obese bad for our health, the growing demand for meat (and tragic for all those animals) is bad for the health of the planet. When we think about environmental sustainability and how we want to leave planet Earth for future generations, we need to begin thinking about what foods we are eating and how much.  I discussed population fatness in this article, but didn’t even touch upon black carbon, nitrous oxide, methane, carbon dioxide and other greenhouse gases released from raising livestock and the strong link between factory farming, and the rate of global temperature rise.  The same foods that are healthiest for us are also healthiest for the planet. Some people reading this blog might only be interested in health and not environmental sustainability or animals. But these issues go hand in hand; we cannot expect ourselves and our children to live a long and healthy life without a healthy planet to sustain us.   We are all in the same bed together and the health of our planet requires a change in eating habits of all, especially in America. 

1. UNFAO (2006). Livestock’s Long Shadow. UN Food and Agriculture Organization (UNFAO). Retrieved from:

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