Earth in 30 years will be home to fatter, taller people whose demands for food will push the planet to its limit, new research warns.
The height and weight of people has gradually increased since 1975 as human food consumption more than doubled.
By 2050 humankind will struggle to feed a population of roughly nine billion people without missing targets to curb climate change and save the rainforests, the report said.
Between 1975 and 2014, the average adult became 14 per cent heavier, about 1.3 per cent taller and needed 6.1 per cent more energy, it showed.
It is the first time scientists have factored in the increased consumption of larger people into the food needs of a larger population.
Co author anfd PhD researcher Gibran Vita, from the Norwegian University of Science and Technology’s Industrial Ecology Programme, said: “It will be harder to feed nine billion people in 2050 than it would be today.
“We studied the effects of two phenomena. One is that people on average have become taller and heavier.
“The second is that the average population is getting older.
“An average global adult consumed 2465 kilocalories per day in 1975. In 2014, the average adult consumed 2615 kilocalories.”
An average human was also 6.2 per cent older in 2014, but the research found lower food consumption among the elderly did little to counter the figures.
Globally, human consumption increased by 129 per cent during this time span.
Population growth was responsible for 116 per cent of that, while increased weight and height accounted for 15 per cent.
The two per cent difference was because of the slightly lower food consumption of elderly people.
Co-author Dr Felipe Vásquez said: “The additional 13 per cent corresponds to the needs of 286 million people.”
He added: “Previous studies haven’t taken the increased demands of larger individuals and aged societies into account when calculating the future food needs of a growing population.
“These assumptions can lead to errors in assessing how much food we’ll actually need to meet future demand.”
The World Wildlife Federation said the world’s greatest problem is the destruction of wildlife and plant habitat.
But the UN’s second “Sustainable Development Goal” is an end to world hunger, which puts increased pressure on the ecosystems, the researchers pointed out.
The team, from the Norwegian University of Science and Technology, also found big differences in change between countries.
Weight gain averages across the 39-year period ranged from six to 33 per cent, while the increased energy requirement ranged from 0.9 to 16 per cent.
An average person from Tonga weighs 93 kilos but an average Vietnamese weighs 52 kilos, which means Tongans need 800 more calories each day – or about four bowls of oatmeal.
Some countries also changed more quickly, with the average weight in Saint Lucia in the Caribbean quickly growing from 62 kilos to 82 kilos.
The lowest and highest changes were found in Asia and Africa, reflecting the disparities between the countries of these continents, the team said.
Changes in the populations of 186 countries between 1975 and 2014 were assessed for the study, published in the sustainability journal.
