Celena and Pete

Celena has put on a whopping five stone since she fell in love with Pete.

He does all the cooking and Celena can't get enough of his high-fat, high-sugar food. But her ballooning weight stops them from enjoying themselves; she won't go on holiday, have their son christened… or marry Pete.

Clinical psychologist Professor Tanya Byron and her team separate the couple for ten weeks in a bid to change their habits - for life. While fitness expert Rick Shakes-Braithwaite puts them on bespoke diet and fitness plans, Tanya delves into the psychological patterns that mean Pete keeps feeding the woman he loves - which stops Celena loving the woman she is.

After Tanya uncovers the source of Pete's hatred of vegetables, behavioural scientist Professor Paul Dolan attempts to retrain his taste buds with a daily dose of broccoli. Meanwhile, Tanya finds out how Celena's negative body-image is getting in her way - and tests the success of the project with a trip to a bridal shop.