This is a question no doubt many people are asking themselves around this time of year, when fad diets and gym memberships are at their peak. In this programme, Dr Xand van Tulleken and dietician Hala El-Shafie help six people go on the most hyped and written about diets on the market to see which works best. In tonight's episode, we meet a girl called Amber, who wants to lose weight for her graduation day with the aid of the mono meal. Cameras also follow Roisin who is on the Dukan diet of lean protein, oat bran and water, and Gerry and Leighton, who are on six-week plans for Leighton's wedding. There's also Janet and Carol who have four months to test out the DNA diet and the apples and pears weight loss regime. As well as that, the show will look at vitamin drips and placenta pills.