Obesity rates climbing worldwide, most comprehensive global study to date shows

However, the rates vary widely throughout the world with more than half of the world's 671 million obese individuals living in just ten countries -- the USA (more than 13%), China and India (15% combined), Russia, Brazil, Mexico, Egypt, Germany , Pakistan, and Indonesia.

Over the past three decades, the highest rises in obesity levels among women have been in Egypt, Saudi Arabia, Oman, Honduras and Bahrain, and among men in New Zealand, Bahrain, Kuwait, Saudi Arabia, and the USA.

In high-income countries, some of the highest increases in adult obesity prevalence have been in the USA (where roughly a third of the adult population are obese), Australia (where 28% of men and 30% of women are obese), and the UK (where around a quarter of the adult population are obese).

The findings come from a comprehensive new analysis of the global, regional, and national prevalence of overweight and obesity in adults aged 20 years and older and children and adolescents aged 2-19 years between 1980 and 2013.

The authors warn that the study presents a worrying picture of substantial rises in obesity rates across the world and say that concerted action is urgently needed to reverse this trend.

Led by Professor Emmanuela Gakidou from the Institute for Health Metrics and Evaluation at the University of Washington in the USA, a team of international researchers performed a comprehensive search of the available data from surveys, reports, and the scientific literature to track trends in the prevalence of overweight (body mass index of 25kg/m² or higher) and obesity (BMI of 30kg/m² or higher) in 188 countries in all 21 regions of the world from 1980 to 2013.

Key findings include:

• In the developed world, men have higher rates of obesity than women, while the opposite is true in developing countries. Currently, 62% of the world's obese people live in developing countries. 
• The greatest gain in overweight and obesity occurred globally between 1992 and 2002, mainly among people aged between 20 and 40.
• Especially high rates of overweight and obesity have already been reached in Tonga where levels of obesity in men and women exceed 50%, and in Kuwait, Libya, Qatar, and the Pacific Islands of Kiribati, Federated States of Micronesia, and Samoa where most (more than 50%) of women are obese.
• The prevalence of overweight and obesity in childhood has increased remarkably in developed countries, from 17% in 1980 to 24% in 2013 in boys and from 16% to 23% in girls. Similarly, in developing countries, rates have risen from roughly 8% to 13% in both boys and girls over the three decades.
• In 2013, the proportion of obesity in girls reached 23% in Kuwait, and 30% or more in Samoa, Micronesia and Kiribati, the highest levels calculated. Similar trends in obesity were found in boys, with the Pacific Islands of Samoa and Kiribati showing the greatest obesity prevalence.
• Within Western Europe, levels of obesity in boys ranged from 14% in Israel and 13% in Malta, to 4% in The Netherlands and Sweden. Levels of obesity in girls were highest in Luxembourg (13%) and Israel (11%), and lowest in the Netherlands Norway, and Sweden (4%). 
• In developed countries, the rate of increase in adult obesity has started to slow down in the past 8 years, and there is some evidence that more recent birth cohorts are gaining weight more slowly than previous ones.

According to Professor Gakidou, "Unlike other major global health risks, such as tobacco and childhood nutrition, obesity is not decreasing worldwide. Our findings show that increases in the prevalence of obesity have been substantial, widespread, and have arisen over a short time. However, there is some evidence of a plateau in adult obesity rates that provides some hope that the epidemic might have peaked in some developed countries and that populations in other countries might not reach the very high rates of more than 40% reported in some developing countries."

"Our analysis suggests that the UN's target to stop the rise in obesity by 2025 is very ambitious and is unlikely to be achieved without concerted action and further research to assess the effect of population-wide interventions, and how to effectively translate that knowledge into national obesity control programmes. In particular, urgent global leadership is needed to help low-and middle-income countries intervene to reduce excessive calorie intake, physical inactivity, and active promotion of food consumption by industry."

Commenting on the implications of the study, Professor Klim McPherson from Oxford University in the UK writes, "An appropriate rebalancing of the primal needs of humans with food availability is essential, which would entail curtailing many aspects of production and marketing for food industries. To prevent unsustainable health consequences, BMI needs to return to what it was 30 years ago. Lobstein calculated that to reduce BMI to 1980 levels in the UK would require an 8% reduction in consumption across the country, costing the food industry roughly £8·7 billion per year."

He adds, "The solution has to be mainly political and the questions remain, as with climate change, where is the international will to act decisively in a way that might restrict economic growth in a competitive world, for the public's health? Nowhere yet, but voluntary salt reduction might be setting a more achievable trend. Politicians can no longer hide behind ignorance or confusion."