Being obese is bad for the environment too, it seems, not just for your health.
Countries with high rates of obesity produce more greenhouse gases than those with thin populations because they consume more food and fuel.
'Slim' nations like Vietnam will consume almost 20 per cent less food and produce fewer carbon emissions than a population in which 40 per cent of people are obese and tend to be more dependent on cars, such as the United States, , researchers at the London School of Hygiene and Tropical Medicine's Department of Epidemiology and Population Health found.
They estimate that a lean population of one billion would emit 1,000 million tonnes less carbon dioxide per year than a 'fat' nation of the same size. The authors, Phil Edwards and Ian Roberts, said: 'When it comes to food consumption, moving about in a heavy body is like driving around in a gas guzzler.
'The heavier our bodies become the harder and more unpleasant it is to move about in them and the more dependent we become on our cars.
'Staying slim is good for health and for the environment. We need to be doing a lot more to reverse the global trend towards fatness, and recognise it as a key factor in the battle to reduce emissions and slow climate change.'
In nearly every country average body mass index (BMI) is rising.
Between 1994 and 2004, the average male BMI in England increased from 26 to 27.3, while the average female BMI went up from 25.8 to 26.9 (about 3kg - or half a stone - heavier).
The study appears in the International Journal of Epidemiology.