The number of overweight people in the world will rise from 1bn today to 1.5bn by 2015, with many developing countries showing the most dramatic increases, the World Health Organisation said on Thursday.

Releasing the estimates ahead of World Heart Day on Sunday, the WHO presaged an alarming increase in chronic diseases, especially heart disease, strokes and type 2 diabetes. Cardiovascular disease is already the world's biggest killer, accounting for 17m deaths a year, 80 per cent ofthem in the developing world.