Engaged couple Ronnie Derrett and Stuart Ellaway from Farnborough want to solve the riddle of why they're putting on weight.

The White Oliver family are desperate to find out how to live a healthier, more balanced diet for the sake of daughter Ellie who is very over weight.

The Meakin family are under the spotlight this week. Mum Sue, daughter Natalie, and son Dave are all needing help to solve the riddle of why they're putting on weight.

This week, Dawn and Mike, a married couple from Hull and their best friend and lodger, Gareth, want to solve the riddle of why they're putting on weight.

The Castle family from Welwyn Garden City are mystified - how can they be putting on weight when they eat mostly healthy, home-cooked food? Using surveillance from cameras in their home, plus private investigators following them outside the house, the Castles are shown what they're really eating. Anna Richardson is on hand to guide them through their discovery, as well as put them on a ten-week healthy-eating regime. Plus, a group of office workers test the theory that by putting sweet treats out of sight, they can be kept out of mind and - more importantly - mouth.

Siblings Jill Hamill and Stuart Raphel from the Wirral are in the spotlight. Both are desperate to lose weight, but convinced they don't eat enough. What will the five-day around-the-clock surveillance reveal? Once Jill and Stuart learn the shocking truth of what they're really consuming, will they be able to stick to a ten-week healthy eating regime, designed by an expert dietician, and win their battle with the bulge for good?