The debate around "size zero" models may dominate today's headlines, but it the world's ever-expanding waistline that is becoming the real global issue.

An estimated 400 million people worldwide are classified as clinically obese, and obesity is now recognised as a major global health threat comparable with HIV/Aids.

This collection of reports by BBC World Service investigates this worldwide phenomenon by looking at science, surgery, body image - and some innovative fat-busting projects in Denmark.

Use the navigation bar to the left to browse and listen to all the BBC World Service programmes taking part in this season.