Blonde and bubbly Bex Upton is too heavy to be weighed on normal scales and 23-year-old Essex girl Anne Odeke is twice the size she should be, despite a family history of diabetes. These girls aren't making any attempts to slim down, so will living with 38-stone Deloris and her 23-stone sister Diane in Mississippi finally make them want to fight their flab?

Snack-guzzling Gary Rowland has ballooned to a whopping 19 stone and is the heaviest he has ever been. 19-year-old Amareen Iqbal is five stone overweight and fears she can't have the family she dreams of. Both of them have given up trying to shed the pounds.

Will the shocking reality of living with a morbidly obese family, and their 19-stone 10-year-old daughter, on Crete make them think about changing their out-of-control ways?

Lauren French is morbidly obese but she doesn't seem overly concerned about her weight, whilst Dan Harrison weighs 24 stone and struggles to beat his junk food addiction. Neither has managed to slim down before, so will living with obese families in Argentina and experiencing life in the most notorious slums of Buenos Aires be the wake up call they need?

At 23 stone, party-loving Carley Brookes loves instant food and refuses to do any exercise. 22-stone Darran Mansfield has been told by his doctor that he is on the brink of full-blown diabetes, yet he's too stubborn to change his unhealthy ways. So will witnessing the effects of living an ultra-lazy lifestyle in Kuwait and meeting a 51-stone recluse have a big enough impact to get the Brits to radically turn their lives around?