The rising number of fat people was blamed for global warming on Monday.
Scientists warned that the increase in big eaters means more food production — a major cause of CO2 gas emissions warming the planet.
Overweight people are also more likely to drive, adding to environmental damage.
Dr. Phil Edwards, of the London School of Hygiene and Tropical Medicine, said: "Moving about in a heavy body is like driving in a gas guzzler."
Each fat person is said to be responsible for emitting a ton more of climate-warming carbon dioxide per year than a thin one.
It means an extra billion tons of CO2 a year is created, according to World Health Organization estimates of overweight people.
The scientists say providing extra grub for them to guzzle adds to carbon emissions that heat up the world, melting polar ice caps, raising sea levels and killing rain forests.