Dr Xand van Tulleken and Dr. Helen Lawal ask members of the public to road test the most hyped diets on the market. This time, Sade and Becky have two weeks to slim down for Lady's Day at the races. Work colleagues Derek and Bruce go on four-week dieting plans ahead of a summer barbecue. Bus drivers Sam and Fay want to slim down for their annual bus drivers picnic in four months' time. The diets tested include the charcoal diet - which replaces one meal per day with charcoal drinks; the breakfast diet, with cake for breakfast; the McDonalds diet; and the super foods diet. Xand also investigates the latest liposuction techniques and finds out if unconscious persuasion can melt away our fat.