What is the Weight of the Nations? Earlier in the year, the CDC hosted a conference, the Weight of the Nation. Now come researchers Sarah Catherine Walpole and colleagues from the London School of Hygiene and Tropical Medicine who have assessed global human biomass, its distribution by regions and by proportions attributable to overweight and obesity. Their findings are, well, a ‘gut-check,’ (if you don’t mind the metaphor.) The numbers are staggering.
They note that more than a billion adults are overweight and, in all regions of the world, the entire population distribution is moving upwards.
So, they calculated that, in 2005, the global human biomass was approximately 287 million tons, of which 15 million tons was attributable to overweight. Biomass due to obesity was 3.5 million tons, equal to 56 million people of average body mass. North America has 6% of the world population but 34% of the biomass due to obesity. Asia has 61% of the world population but 13% of the biomass due to obesity.
One ton of human biomass equates to approximately 12 adults in North America, 17 adults in Asia. According to the authors, “The average BMI in USA in 2005 was 28.7. If all countries had the same age-sex BMI distribution as the USA, total human biomass would increase by 58 million tonnes, a 20% increase in global biomass and the equivalent of 935 million people of world average body mass in 2005. This increase in biomass would increase energy requirements by 261 kcal/day/adult, which is equivalent to the energy requirement of 473 million adults. Biomass due to obesity would increase by 434%”. In contrast, they note that if all countries had the same BMI distribution as Japan, total biomass would fall by 14.6 million tons, a 5% reduction in global biomass or the mass equivalent of 235 million people of world average body mass. This would decrease energy requirements by an average of 59 kcal/day per adult, equivalent to the energy requirement of 107 million adults. Biomass due to obesity would be reduced by 93%.
The authors conclude that, “Increasing population fatness could have the same implication for world food energy demands as an extra half a billion people living on the earth.” See PubMed: The weight of nations: an estimation of adult human biomass