LONDON High rates of obesity in richer countries cause up to 1bn extra tonnes of greenhouse gas emissions every year, compared with countries with leaner populations, according to a study that assesses the additional food and fuel requirements of the overweight. The finding is particularly worrying, scientists say, because obesity is on the rise in many rich nations.

“Population fatness has an environmental impact,” said Phil Edwards, from the London School of Hygiene and Tropical Medicine. “We`re all being told to stay fit and keep our weight down because it`s good for our health. The important thing is that staying slim is good for your health and for the health of the planet.”

The study, carried out by Edwards and Ian Roberts, was published in the latest issue of the International Journal of Epidemiology.

In their model, the researchers compared a population of a billion lean people, with weight distributions equivalent to a country such as Vietnam, with a billion people from richer countries, such as the US, where about 40 per cent of the population is classified obese, having an average body mass index (BMI) of more than 30.

They found the fatter population needed 19 per cent more food energy for its total energy requirements. They also factored in greater car use by the overweight. “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,” they wrote.

The greenhouse gas emissions from food production and car travel for the fatter billion people were estimated at between 0.4 billion and 1 billion extra tonnes a year. That is a significant amount in comparison with the world`s total emissions of greenhouse gases, which was 27 billion tonnes in 2004.

Edwards said the billion rich people in the model could represent the combined populations of Europe, the US, Australia and other nations with obesity problems. Last September the world`s leading authority on climate change controversially suggested people should eat less meat to curb global warming, because it is argued meat production causes 20 per cent of global emissions.

Rajendra Pachauri, Chairman of the United Nations Intergovernmental Panel on Climate Change, said consumers should begin with one meat-free day a week and then cut back even further if they wanted to make a personal and effective sacrifice that would help tackle climate change.

Kath Dalmeny, Policy Director of Sustain, a food and farming campaign group, said “It should come as no surprise that unhealthy food and lifestyles are also bad for the planet.

Obesity and climate change are both symptoms of over-consumption. The types of food that cause people to gain weight also use a lot of energy to produce, with high levels of fat and sugar, and with lots of wasteful processing and packaging.”

Around the world, the average weight of populations is rising. According to the World Health Organisation, there were 1.6 billion overweight adults in the world in 2005, classified as anyone with a BMI greater than 25. In the same year, there were 400 million obese people. By 2015, the WHO estimates these figures will rise to 2.3 billion and 700 million respectively.

The latest research is part of a larger study by the LSHTM to look at the health benefits of climate change mitigation policies. Edwards said the work would be fed directly into the agenda for the upcoming UN climate change treaty negotiations in Copenhagen in December. —Dawn/The Guardian News Service