Obese and overweight people require more fuel to transport them and the food they eat, and the problem will worsen as the population literally swells in size, a team at the London School of Hygiene & Tropical Medicine says. 

    This adds to food shortages and higher energy prices, the school's researchers Phil Edwards and Ian Roberts wrote in the journal Lancet on Friday.

    "We are all becoming heavier and it is a global responsibility," Edwards said in a telephone interview. "Obesity is a key part of the big picture."

    At least 400 million adults worldwide are obese. The World Health Organization (WHO) projects by 2015, 2.3 billion adults will be overweight and more than 700 million will be obese.

    In their model, the researchers pegged 40 percent of the global population as obese with a body mass index of near 30. Many nations are fast approaching or have surpassed this level, Edwards said.

    BMI is a calculation of height to weight, and the normal range is usually considered to be 18 to 25, with more than 25 considered overweight and above 30 obese.

    The researchers found that obese people require 1,680 daily calories to sustain normal energy and another 1,280 calories to maintain daily activities, 18 percent more than someone with a stable BMI.

    Because thinner people eat less and are more likely to walk than rely on cars, a slimmer population would lower demand for fuel for transportation and for agriculture, Edwards said.

    This is also important because 20 percent of greenhouse gas emissions stem from agriculture, he added.

    The next step is quantifying how much a heavier population is contributing to climate change, higher fuel prices and food shortages, he added.

    "Promotion of a normal distribution of BMI would reduce the global demand for, and thus the price of, food," Edwards and Roberts wrote.

    伦敦卫生与热带医学院的一个研究小组日前称，肥胖和体重超标人士在日常生活中消耗的交通燃料和食物都更多；而且随着人们体型的“发福”，这一问题会不断加剧。

    该学院研究员菲尔•爱德华和伊安•罗伯茨在上周五出版的《柳叶刀》杂志中写道，肥胖会加剧食品短缺及能源价格上涨问题。

    爱德华在接受电话采访时表示：“人们的体重正在不断增加，这是个需要全球关注的问题。肥胖是这一问题的关键所在。”

    目前全世界至少有4亿成年人存在肥胖问题。而据世界卫生组织估计，到2015年，将有23亿成年人体重超标，7亿多人将存在肥胖问题。

    在该研究中，研究人员将全世界40%的人口归入了肥胖人群，这些人的体重指数都接近30。据爱德华介绍，目前很多国家很快就会达到或已超过这个水平。

    体重指数是一个以身高与体重为基础计算出的比值，其正常范围通常在18和25之间，超过25为超重，超过30即为肥胖。

    研究人员发现，肥胖人士每天需要1680卡的热量来维持正常体能和1280卡的热量来进行日常活动，比一个体重指数在正常范围内的人多18%。

    爱德华还说，因为较瘦的人吃的少，而且他们出行时更愿意步行而不是乘车，所以，如果人们都变苗条了，对燃料和农产品的需求就会减少。

    他说，这个问题之所以重要还在于目前全球20%的温室气体排放都来自于农业。

    爱德华还提到，下一步我们要测算体重超标人群对气候变化、油价上涨及食品短缺等问题的影响究竟有多大。

    爱德华和罗伯茨在研究报告中写道：“促进体重指数的正常分布将能够减少全球的粮食需求，从而抑制粮价的上涨。”