The world’s obesity epidemic can only be tackled through a huge international effort to “transform the environment that is making us fat”, an effort echoing the global fight against climate change, nutritional scientists told the American Association for the Advancement of ­Science meeting in Boston on Sunday.

Philip James, chairman of the United Nations Commission on the Nutritional Challenges of the 21st Century, said there was great synergy between the measures needed to tackle climate change and the pressing need to transform the environment for diet and physical activity.