Dr Christian flies out to Evansville, Indiana, officially America's 'Fattest City', where 38% of the population is obese.

Experts predict that by 2020 a third of adults in the UK will be obese. But in America this milestone has already been reached. He meets a woman who lost her foot to obesity-related diabetes, and visits a funeral home where the coffins are the size of hot tubs!

In the Feeding Clinic, Supersize and Superskinny go on a shocking diet swap. But before they swap diets, Christian gives his Supersizer a terrifying glimpse into the future by sending them to the US, to spend time with somebody whose obesity has ruined their life.

The new series also examines a variety of eating disorders as six men and women reveal their very personal stories. In this episode, 18-year-old it's Ellie Lambert, whose anorexia was triggered by a jaw operation that prevented her from eating.

Foodaholic Rob Gillett goes head to head with foodphobic Hayley Payne in the Feeding Clinic. And Dr Christian goes for a ride on a supersize ambulance in America's fattest town.

Rob Gillett's obsession with donuts and cream cakes has seen him eat his way to an enormous 35 stone 10 pounds. While on the other end of the scale, for busy-bee Hayley food isn't a priority - which has left her weighing in at just 6 stone 12 pounds.

And the warning signs of bulimia are revealed through the eyes of 20-year-old Lucy Glover, who regularly binges and purges on a staggering 8000 calories at a time.

In the Feeding Clinic comfort eater Hugh meets Lynsey, who has a fear of choking. And fashion student Laura reveals how an eating disorder has left her addicted to exercise and surviving on just 600 calories a day.

Snackaholic Geoff Milton meets sweet-toothed meal skipper Josh Bryson in the Feeding Clinic. And Dr Christian visits an after-school nutrition class in America's fattest city.

Head to head in the Feeding Clinic are Jo from Staffordshire and Emma from Lincolnshire.

Former anorexic Rosemary recounts her story, from the depths of the disease through to her amazing recovery.

And in Evansville, America's fattest town, Dr Christian witnesses life-saving surgery for the super obese, meeting the bariatric surgery team who perform the very latest gastric bypass operation.

Takeaway addict Chris Longley swaps diets with meal-skipping hairdresser Nathan Smith - and gets a shock when he is sent to stay with a 32st American man whom doctors believe has five years to live. A 19-year-old reveals why his disordered eating has caused him to lose 11st in nine months, and Christian Jessen visits an overeaters' support group in Evansville, Indiana (Christian Jessen)

Saskia Roberts, a 23-year-old Caribbean cuisine enthusiast, trades diets with 25-year-old food analyst Nick Harvey, who refuses to eat anything without identifying its contents first. Dr Christian Jessen also visits Evansville, Indiana, to tuck into a rack of baby back ribs containing 2,300 calories, and introduces 30st Lisa Bockus, who had to terminate a pregnancy because of her weight (Christian Jessen)

This edition revisits three former Supersize vs Superskinny feeding clinic inmates: chronic food dodger Josh Evans, five-course food-lover Louise Hayes and foodphobic Vicki Smith.

One year down the line have they managed to ditch their dangerous eating habits for good?

One year after checking into the Feeding Clinic, have over-eater James and under-eaters Modasser and Ami stuck to their new eating plans or reverted to their old, very unhealthy ways?