Kicking off the mini series is 15-year-old Ieuan Rosser, who weighs 17 stone, and 13-year-old Jess, who weighs six and a half stone. It's not an easy ride for Ieuan who is used to consuming a a shocking 4000 calories a day. Nor for his mum Kay who's forced to face up to why she hasn't been able to stop her son from putting on weight. Meanwhile super fussy Jess's inability to try new healthier foods is put to the test. But can laidback dad Dave finally do what he should have done years ago and put his foot down when it comes to his daughter's unhealthy diet? But it's not just Mums and Dads who need to take responsibility for their children's diets, and so Dr Jessen's on a mission to get the nation's kids to take charge of what they put in their mouths too. Using actual samples of human bodies, he delivers the first of four hard-hitting lectures to a group of junk-loving school kids on the strain that eating too much or too little puts on the heart. The Supersizers get a glimpse into what the future might hold as they watch personal video messages from America. Fifteen-year-old Hayli Cohen from New York state weighs in at a hefty nineteen stone. Allowed to eat whatever she wanted after her parents divorced when she was three years old, Hayli's weight soared. She's even resorted to having a gastric band fitted - something Ieuan is also considering. But will her experience and words of warning give him and Mum Kay the push they need to sort out his diet for good? Also the harrowing tale of 16-year-old Erin Wade, whose eating disorder spiralled out of control after she became addicted to pro-anorexia websites.
Dr Christian meets 12-year-old ballet dancer Caitlin Anstis and 11-year-old Declan Garner who's been bullied because of his supersize frame. Declan weighs in at a colossal eleven and a half stone. He's desperately unhappy about the way he looks and it's taking its toll on his quality of life - he won't even go swimming with his friends because he's so embarrassed about his size. Mum Bev is a soft touch who feeds her son whatever he wants. As they receive potentially lifesaving nutritional advice, the pair also receive a hard hitting message from American teen Alexandria, who at just thirteen years old weighs in at a super-supersized 24 stone. Six stone Caitlin dreams of becoming a prima ballerina. But when it comes to food, she's more of a prima-donna. A simple bowl of porridge reduces Caitlin to tears. Dr Jessen knows that extreme measures are in order and has lined up a message from Mara Galeazzi, principal dancer with the Royal Ballet. Will Mara's tales of broken bones and broken dreams convince Caitlin to wake up to what the future may hold if she doesn't change her diet? And another bunch of rowdy school kids come face to face with real human bodies as Dr Jessen warns of the impact of bad eating on our bones.
Eleven-year-old Aiyesha, who weighs almost 12 stone, meets nine-year-old David, who weighs a miniscule three stone 12 pounds. Aiyesha is double the weight she should be for her age. And that's because her mum is scared of her daughter's explosive temper. Can a reality check from 16-year-old American teenager Brianna, who weighs 25 stone, convince Aiyesha to change her terrible diet for good? Nine-year-old David exists on a diet of processed foods and his favourite chocolate milkshakes. With her son refusing almost everything she cooks and shunning most fruit and vegetables, mum Paula is seriously concerned that his fussy eating will turn into something far more serious.
Eleven-stone Cameron, who grazes on sugary snacks all day, meets 15-year-old Aled, who's is literally too scared to eat. In this episode two families who are polar opposites when it comes to food come together in the feeding clinic. Eleven-year-old Cameron weighs almost four stone more than he should. But according to mum Eloise, it's not because she lets him eat too much - it's just `food likes Cameron'. As Eloise finally admits responsibility for her son's weight gain, Cameron gets a postcard from America from 13-year-old Travis who weighs in at a mammoth eighteen stone. Can his words of warning shock Cameron into turning his life around before it's too late? Aled weighs in at just over seven stone. It is a huge concern for his mum Jayne who used to be an anorexic. When Aled's weight dropped to just five and a half stone last year his mum knew that something was seriously wrong. Aled was diagnosed with Crohn's Disease. But despite not suffering an attack in the last eight months, he still refuses to try new foods. So Dr Jessen has lined up some gruesome pictures to show Aled what could happen to his body if he doesn't change his ways. But will the shock tactics work? And the programme hears from 16- year-old Emily, whose pursuit of perfection led to anorexia and nearly killed her.