Thirty-four-year-old junk food addict Jackie Kenworthy meets 70-year-old great grandmother Beth Edwards, who lives on a diet of egg and toast.
Jackie visits Salem, North Carolina, to meet Nikki, who weighs in at over 51 stone.
Dr Christian continues his tour of Las Vegas, the capital of excess, to investigate its obesity crisis.
And Emma Woolf looks at dedicated hospital in-patient care for people with eating disorders.
