肥胖已经被世界卫生组织(WHO)定义为全球范围的流行病(global epidemic)[1],目前全球10亿以上成人超重,其中3亿肥胖。WHO预测,到2015年,全球成人超重人口将达到23亿,肥胖人口超过7亿。无论是发达国家还是发展中国家,肥胖率均已经达到很高的水平。美国1/3的成人超重或肥胖,其中1 Obesity has been defined by the World Health Organization (WHO) as a global epidemic [1] and is currently over 1 billion adults worldwide, of which 300 million are obese. WHO predicts that by 2015, the global adult overweight population will reach 2.3 billion and the obese population will exceed 700 million. No matter in developed countries or developing countries, the obesity rate has reached a very high level. One third of adults in the United States are overweight or obese, including 1