It's fireworks in the feeding clinic as 24 stone call centre agent Julie meets superskinny caffeine addict Jade.

Jade weighs just five and half stone, and is desperate to regain her pre-pregnancy size for the sake of her young son. While Jade barely eats a thing, Julie, whose lack of confidence is stopping her from following her dream to be a schoolteacher, binges on huge platefuls of home cooked food, from massive cream filled curries to cheesy topped shepherds' pies.

Dr Christian pushes the diet swappers to look beyond what's on their plates to explore the psychological triggers that lead to their dangerous diets. But Julie goes into meltdown when she's accused of lying about what she eats by Jade.

In 'Postcards from America', a new strand of hard-hitting short films featuring morbidly obese Americans, 37 stone Alaina Morgan from Santa Rosa, California, makes a plea to Julie to lose weight before it's too late.

Presenter and serial dieter Anna Richardson is two stones lighter than when she two years ago, but admits that she continues to be obsessed with getting the perfect body. In this film she investigates the very latest diet products and exercise fads.

The show also takes a glimpse into the lives of three women and one man in the grip of the mental illness anorexia nervosa, following their progress over the series as they explore the causes of their condition under the guidance of eating disorder specialist Dr Peter Rowan.