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.

    倫敦衛生與熱帶醫學院的一個研究小組日前稱，肥胖和體重超標人士在日常生活中消耗的交通燃料和食物都更多；而且隨著人們體型的“發福”，這一問題會不斷加劇。

    該學院研究員菲爾•愛德華和伊安•羅伯茨在上周五出版的《柳葉刀》雜志中寫道，肥胖會加劇食品短缺及能源價格上漲問題。

    愛德華在接受電話采訪時表示：“人們的體重正在不斷增加，這是個需要全球關注的問題。肥胖是這一問題的關鍵所在。”

    目前全世界至少有4億成年人存在肥胖問題。而據世界衛生組織估計，到2015年，將有23億成年人體重超標，7億多人將存在肥胖問題。

    在該研究中，研究人員將全世界40%的人口歸入了肥胖人群，這些人的體重指數都接近30。據愛德華介紹，目前很多國家很快就會達到或已超過這個水平。

    體重指數是一個以身高與體重為基礎計算出的比值，其正常范圍通常在18和25之間，超過25為超重，超過30即為肥胖。

    研究人員發現，肥胖人士每天需要1680卡的熱量來維持正常體能和1280卡的熱量來進行日�；顒�，比一個體重指數在正常范圍內的人多18%。

    愛德華還說，因為較瘦的人吃的少，而且他們出行時更愿意步行而不是乘車，所以，如果人們都變苗條了，對燃料和農產品的需求就會減少。

    他說，這個問題之所以重要還在于目前全球20%的溫室氣體排放都來自于農業。

    愛德華還提到，下一步我們要測算體重超標人群對氣候變化、油價上漲及食品短缺等問題的影響究竟有多大。

    愛德華和羅伯茨在研究報告中寫道：“促進體重指數的正常分布將能夠減少全球的糧食需求，從而抑制糧價的上漲。”