Surgeon Gabriel Weston wants to find out why we're getting fatter. Ultimately she doesn't believe that it's simply a failure of self-control. She knows that the usual advice - to eat less and exercise more - just isn't working for most of us. From the power of hormones on our appetite to stomach surgery, from genetics to the impact of a pregnant woman's diet on her unborn child, Gabriel discovers the surprising truth behind the obesity epidemic and asks whether science can help us change