An impending global food crisis could be averted, at least in part, if the world follows the Japanese instead of adopting the lifestyle of the Americans, according to a new study which weighed the human race to measure its calorie needs.

A research team from the London School of Hygiene and Tropical Medicine (LSHTM) used an innovative way to size up the mounting global food security crisis. Unlike earlier studies, which counted the number of mouths to be fed to figure out the magnitude of the problem, the UK researchers took into account how much people weigh and also factored in the extra pounds due to overweight and obesity.

The study, which appeared in the journal BMC Public Health last week, estimated that the adult human population has a cumulative weight of 287 million tonnes.

“In a world where millions of people lack adequate food supplies and global environmental change threatens food supply, we wanted to quantify the impact of average consumption on food demand,” says Sarah Catherine Walpole, a junior doctor with North Yorkshire and an author of the study.

“Food security and environmental sustainability are threatened not only by the number of people in the world but also the amount of flesh that needs to be fed,” Walpole told KnowHow.

The world population is growing at a rapid pace and its energy requirement is also mounting. Besides, average body mass is increasing across all countries and in many countries the average person is already overweight (body mass index, or BMI, over 25). Any person with a BMI over 30 is considered obese.

Up to half of all food eaten is burned up in physical activity. Increasing mass means higher energy requirements, because it takes more energy to move a heavy body. Even at rest a bigger body burns more energy.

While the average global body mass was 62kg, North America has the highest body mass in any continent, with an average body mass of 80.7kg. North America has only 6 per cent of the world’s population but accounts for 34 per cent of the world’s biomass due to obesity. In contrast Asia has 61 per cent of the world’s population but only 13 per cent of the world’s biomass due to obesity. The total extra biomass of the world due to overweight and obese people is 15 million tonnes and 3.5 million tonnes respectively.

If all countries had the same average BMI as the US the total human biomass would increase by 58 million tonnes — this is equal to feeding an additional 935 million mouths.

On the other hand, if all the people in the world have the BMI of an average Japanese person, the cumulative human biomass will shrink by 5 per cent, the scientists say.

Indians may account for 16.6 per cent of global population in terms of numbers, but their share in global biomass is 14.2 per cent.

This study is based on demographic and BMI data available from the United Nations and the World Health Organization for the year 2005. The world’s population is continuing to increase in size – the UN predicts that by 2050 there could be 8.9 billion people on the planet.

Undoubtedly, this study is interesting. But such a macro picture could be deceiving at times, says B. Sesikeran, director of the National Institute of Nutrition, in Hyderabad. For instance, he says, per capita edible oil consumption of nearly 60 per cent of Indian population is 12gm per day, whereas the rest consumes an average 40gm per day. Taken together, it may look like a healthy average, but it actually masks the reality. “The affluent should actually reduce their consumption by 15gm per day which can then be made available to the poor,” says Sesikeran.

“Everyone accepts that population growth threatens global environmental sustainability — our study shows that population fatness is also a major threat. Unless we tackle both population and fatness — our chances are slim,” says Ian Roberts of LSHTM and an author of the study.

The scientists say they plan to take this study forward by extending the research to include more recent data, data for children and predicted future population numbers. The current study focussed only on adult human population, which was 4.63 billion according to the 2005 data.

“We can model how global food energy requirements differ depending on average BMI. We hope this will provide a wake up call to governments to prepare for future food demand, and take action to stem the trend of increasing average body mass in already overweight populations,” says Walpole.