The global obesity epidemic means fat people will soon be eating enough extra food to feed 1billion others, scientists say.
As more people in Europe and North America become obese, the amount of energy they need from food increases, they add.
The fatter we get, the more energy-dense food we think we need. Put another way, the fatter we get, the more calories we consume.
By 2050, the world’s population is expected to be 2.3billion higher than now and the ecological impact of that will be worsened by increases in obesity.
‘Tackling population fatness may be critical to world food security and ecological sustainability,’ said prof Ian Roberts, who led the research at the London School of Hygiene and Tropical Medicine.
‘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.’ The world’s adult population weighs 287million tonnes, 15million of which is due to being overweight and 3.5million is due to obesity, according to the study.
If everyone had the same average body mass index as North Americans, the total human biomass would rise by 58million tonnes.
Some 75 per cent of North Americans are overweight compared with 55 per cent of Europeans.
In his new book The Energy Glut, prof Roberts links the use of fossil fuels with the steep rise in human weight.
We are eating large amounts of high-calorie food while at the same time becoming ‘functionally paralysed’ with fewer opportunities to move our bodies than ever before.
He argues that the accumulation of body fat is a political, not a personal, problem. Across Europe, the average weight (for men and women) was 70.8kg (11st 2lb). In Asia, this was 57.7kg (9st 1lb).
Almost a quarter of British adults are classified as obese.