According to the new research, levels of national fatness – and not just population size – should be taken into account when planning how to deal with increasing demand for food.
Writing in BMC Public Health, the researchers argue that the energy requirement of a species depends not only on numbers but on its average mass.
With this in mind they noted that if all countries had the same average BMI as the USA the total human biomass would increase by 58 million tonnes – the equivalent of an additional 935 million people.
Led by Professor Ian Roberts from the London School of Hygiene & Tropical Medicine, UK, the researchers reveal that despite only contributing towards 6% of the global population, North America counts for more than a third (34%) of the world’s biomass mass due to obesity.
In contrast Asia has 61% of the world’s population but only 13% of the world’s biomass due to obesity, they said.
“Everyone accepts that population growth threatens global environmental sustainability – our study shows that population fatness is also a major threat,” said Roberts. “Unless we tackle both population and fatness our chances are slim.”
Growing population, shortening supply
In 2012 the United Nation’s Food and Agriculture Organization (FAO) estimated that 920 million people—one-eighth of the world’s population—do not have enough food to meet their daily caloric intake target.
Last year world population passed the 7 billion mark, with projections that by 2050 this figure will rise to 9 billion. By that point the FAO estimates that food production will have to rise by 70%.
Meanwhile, obesity rates are soaring globally – putting an even higher demand on what is already a limited supply.
The new research estimates the total mass of the human population, defined its distribution by region, and the proportion of this biomass due to the overweight and obesity.
Using data from the United Nations and World Health Organization, Roberts and his colleagues estimate that the adult human population weighs in at 287 million tonnes – 15 million of which is due to the overweight and 3.5 million of which is due to obesity.
Dr Sarah Walpole, a co-author of the study, noted that the results “emphasise the importance of looking at biomass rather than just population numbers when considering the ecological impact of a species, especially humans.”
The authors add that the data used in the study is from a 2005 WHO report – meaning it is a likely underestimation of the current situation
Source:BMC Public Health
Published online ahead of print, doi: 10.1186/1471-2458-12-439
"The weight of nations: an estimation of adult human biomass"
Authors: S.C. Walpole, D. Prieto-Merino, P. Edwards, J. Cleland, G. Stevens, I. Roberts