The UK diet industry is worth a billion pounds, and growing. For slimming clubs, business is booming. And for the millions of men and women who join groups every year, the title of Slimmer of the Year would be a dream come true. But once you’ve won the award, what happens next? Slimming journalist Sally Ann Voak catches up with three Slimmer Champions, six years after their awards to find out whether they have put their weight back on and whether they are still diet-obsessed.