Si King and Dave Myers embark on a quest to lose weight while still enjoying the food they love by creating healthier versions of their favourite recipes, and ask fellow dieters to test the new, low-calorie dishes.

Si King and Dave Myers continue their dietary challenge by reinventing favourite family meals. They come up with a cooked breakfast that delivers all the excitement of a fry-up without adding to the waistline, and a calorie-conscious roast chicken dinner.

Si King and Dave Myers come up with a fat-friendly pie for fellow dieter Ann, baking a pastry treat that comes in below the 700 calories of a standard pork pie - but keen to lose as much weight as they can, they don't taste it themselves. Moving on to Dave's home town of Barrow-in-Furness in Cumbria, the duo try to persuade the diners in Chinese and Indian restaurants that their favourite dishes can be even better with all the fattening elements removed.

Si King and Dave Myers create low-calorie versions of their favourite party treats, including fairy cakes, quiche and chilli tacos, and Olly Smith offers advice on wines suitable for slimmers. The duo then reflect on how trying to lose weight has improved their lives and learn whether the Big Dieters have also managed to change their eating habits - before paying a final visit to diabetes expert Roy Taylor and dietician Ashley Adamson to discover if their new diets have yielded the desired results. Last in the series.