London, Dec 20 (IANS): Researchers have found that increasing average body size of people on Earth, in addition to the growing world population may further challenge attempts to reduce man-made carbon dioxide emissions.

The study, published in the journal Obesity, shows obesity is associated with approximately 20 per cent greater greenhouse gas emissions when compared to people with normal weight.

"Our analysis suggests that, in addition to beneficial effects on morbidity, mortality, and healthcare costs, managing obesity can favourably affect the environment as well," said study researcher Faidon Magkos from the University of Copenhagen in Denmark.

"This has important implications for all those involved in the management of obesity." Magkos said.

According to the researchers, people with obesity have greater carbon dioxide production from oxidative metabolism than individuals with normal weight.

Also, maintenance of greater body weights requires more food and drinks to be produced and transported to the consumers. Similarly, transportation of heavier people is associated with increased consumption of fossil fuels.

This results in additional carbon dioxide emissions related to food production and transportation processes.

Globally, obesity was estimated to contribute to an extra 700 megatons of carbon dioxide emissions per year or about 1.6 percent of all man-made emissions.

To assess the impact of obesity on the environment, researchers used the standard definitions of obesity (body mass index of greater than or equal to 30 kg/m2) and normal weight (body mass index of less than 25).

Calculations were made of the extra emission of greenhouse gases (carbon dioxide, methane, and nitrous oxide) from the increased oxidative metabolism, the increased food production and consumption and the increased fuel used to transport the greater body weight of people with obesity.

Compared with an individual with normal weight, the researchers found an individual with obesity produces an extra 81 kg/year of carbon dioxide emissions from higher metabolism, an extra 593 kg/year of carbon dioxide emissions from greater food and drink consumption and an extra 476 kg/year of carbon dioxide emissions from car and air transportation.

"Harmonising data from prevalence rates of obesity, total energy intake and expenditure and carbon dioxide emissions from different sources is not a straightforward task, and we emphasize that our estimates are not intended to be precise, but rather be reasonable enough," said Magkos.

"While the contribution of obesity to greenhouse gas emissions is small, acting on the underlying drivers of them both is of paramount importance," he added.