Researchers at the London School of Hygiene and Tropical Medicine published a study showing that, because of food production and transportation factors, a population of heavier people contributes more harmful gases to the planet than a population of thin people.

Given that it takes more energy to move heavier people, transportation of heavier people requires more fuel, which creates more greenhouse gas emissions, the authors write.

"The main message is staying thin. It's good for you, and it's good for the planet," said Phil Edwards, senior lecturer at the London School of Hygiene and Tropical Medicine.

The study offers this novel approach to the global warming problem as U.S. lawmakers discuss the future of climate change legislation. This week, the the House Energy and Commerce Committee is scheduled to begin on a comprehensive energy and climate bill. On Friday, the Environmental Protection Agency announced that six greenhouse gases pose potential health hazards, an announcement that could prompt the regulation of the gases.

More than 1 billion adults worldwide are overweight, and about 300 million are obese, the study said. Generally, the body mass index, a measure of obesity, is increasing in most countries worldwide, from China to European countries to the United States.

BMI is going up because of the availability of food and motorized transportation, Edwards said. People are less active now than they were 30 years ago, and the prevalence of fast food has given people less healthy, more energy-dense options.

Using statistical models, the authors compared the distribution of BMI in the United Kingdom in the 1970s -- when 3.5 percent of the population was obese -- with a prediction for the country's BMI distribution in 2010, reflecting 40 percent obesity.

"In terms of environmental impact, the lean population has a much smaller carbon footprint," Edwards said.

The population with 40 percent obese people requires 19 percent more food energy for its total energy expenditure than the population with 3.5 percent obese people, the study showed.

This 19 percent increase in food consumption translates into an increase of 270 million metric tons of greenhouse gas emissions, the study said.

"The findings make sense and highlight an important global co-benefit of losing weight, along with the significant personal health benefits," said Patrick Kinney, associate professor at Columbia University's Mailman School of Public Health, who was not involved in the study.

In terms of obesity rate, the U.S. population is not far off from the overweight population model in this study. The country has 33.3 percent obese people, according to the Mayo Clinic.

The study suggests that governments have a responsibility to encourage people to be more physically active, Edwards said. Active transportation, such as cycling and walking, helps maintain a healthy weight but requires safe streets, he said.

"If the government wants to promote active transport, which would be good for the environment and for individual health, it needs to make the environment safe to do that," he said.

Although climate change has come into the forefront as a major world problem recently, this is not the first time scholars have thought about the connection between fossil fuel and body fat.

In 1978, a year the United States experienced an oil shock, a study in the American Journal of Public Health showed that if all overweight people in the country aged 18 to 79 reached their optimal weight, the resulting energy savings would equal 1.3 billion gallons of gasoline.

After the dieting period, about 750 million gallons of gasoline would be saved every year, said the authors, Bruce Hannon, professor at the University of Illinois, Urbana-Champaign, and Timothy Lohman, now professor emeritus at the University of Arizona.

Today, research has shown that the obesity epidemic costs the United States about $100 billion a year, said Dr. Martin Donohoe of Portland State University, who runs the Web site Public Health and Social Justice. In terms of energy expenditure, the average food product travels 1,500 miles to get to your table, he said.

Some measures to curb obesity include making healthier meals available in schools, putting nutritional information on food packages and menus, and banning trans fats, he said.

伦敦卫生和热带医学学院的研究者们发布的最新研究结果显示，由于食品生产加工和运输等因素，超重的人群比瘦人们向地球“贡献”更多的有害气体。

研究者们写道，考虑到移动胖人需要消耗更多的能量，体重更大者的运输就需要更多的燃料，这造成了更多的温室气体排放。

伦敦卫生和热带医学学院的高级讲师菲尔爱德华兹说，“报告主题就是要保持苗条身材。这有利于你个人，也有利于地球。”

美国立法者们正在讨论有关气候变暖立法的未来，而此时这项研究提供了一个解决全球变暖问题的新方法。众议院能源和商务委员会定于本周提交一份综合能源和气候议案。周五时，环保署宣布6种温室气体会造成潜在的健康危害，这将推动有关气体方面的管理。

研究称，全球有超过十亿成年人超重，其中大约有3亿人过度肥胖。总体而言，从中国到欧洲，再到美国，世界大多数国家的BMI（体重指数——肥胖测量标准）一直在增长。

BMI因为食物更加容易获得和机械化运输的实现而持续上升。因为人们比30年前更加懒散，快餐的流行也给了人们健康程度降低但热量增加的选择。

研究者们使用统计模型，比较了上世纪70年代英国的BMI分布数据与2010年的分布预测。前者的人口肥胖率为3.5%,而后者为40%。

爱德华称：“就对环境的影响而言，体型瘦小人群的碳足迹要小得多。”

研究显示，拥有40%肥胖率的人口，其所需能源消耗要比肥胖率为3.5%的人口多19%。

这19%的食物消费增长相当于新增2.7亿吨温室气体的排放。

哥伦比亚大学邮差公共卫生学院的副教授Patrick Kinney并未参与此项研究，但他认为：“这些结果非常有意义，它们揭示了减肥是为了全球的共同利益，对个人健康也益处良多。”

按照美国目前的人口肥胖率，研究中的超重人口模型并非遥不可及。根据Mayo Clinic的数据，美国现在拥有33.3%的肥胖人口。

爱德华认为，该项研究建议政府应承担其责任，鼓励人们参加更多的体育活动。诸如骑车和散步等积极的运动，可以帮助保持健康的体重，但这需要安全的街道。

“如果政府想推广此类运动——这对环境和个人健康都有益，那么它必须创造一个安全的环境。”

虽然气候变化最近已经作为一个世界性难题提上议程，但这并非学者们第一次考虑化石能源和人体脂肪之间的联系。

早在1978年，美国经历石油危机之时，《美国公共健康杂志》的一项研究就显示，如果美国从18岁到79岁的所有超重人口都保持理想体重，那么由此节省下来的能源相当于13亿加仑汽油。

据伊利诺斯大学香槟分校教授Bruce Hannon和亚利桑那大学的荣誉教授Timothy Lohman估计，在节食期过后，大约每年将节省7.5亿加仑汽油。

来自波特兰州立大学的Martin Donohoe教授说，目前研究已经显示美国每年因肥胖症流行损失一千亿美元，按照其能源消耗计算，食品在抵达餐桌之前平均需要旅行1500英里。

他说，阻止肥胖的措施包括在学校尽量提供更健康的饮食，在食品包装和菜单上印制营养信息，还有取缔反式脂肪酸。