30% of the world’s population are either obese or overweight, according to a new study published last week by British medical journal The Lancet. The number of overweight and obese people increased from 857 million in 1980 to 2.1 billion in 2013. The researchers used data covering 188 nations from 1980 to 2013. Worldwide, the prevalence of overweight and obesity rose by 27,5% for adults and 47,1% for children over the past 33 years. The proportion of adults who were overweight - defined as a body-mass index (BMI) of 25 or more - increased from 28,8% to 36,9% in men, and from 29,8% to 38,0% in women. Because of the increases in prevalence, the study warned that obesity has become a major global health challenge. Not a single country has reported a decline in the last three decades, the researchers said. Increases were recorded in both developing and developed countries. More than half of the 671 million obese people live in 10 countries, topped by the United States and followed by China, India, Russia, Brazil, Mexico, Egypt, Germany, Pakistan and Indonesia. The prevalence of obesity exceeded 50% in men in Tonga and in women in Kuwait, Kiribati, Micronesia, Libya, Qatar, Tonga, and Samoa. In North America, the USA stood out with roughly a third of men and women being obese. To tackle the problem, urgent global action is needed to help countries to more effectively intervene against major determinants such as excessive caloric intake, physical inactivity, and active promotion of food consumption by industry, the study concluded.