Britain is a nation obsessed with celebrity chefs but all that gourmet cooking is making us fat. Our favourite chefs have seduced us with their glossy recipes and deliciously indulgent dishes, using bucket loads of butter, cheese, sugar and oil. They taste great but make us look enormous.

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Never again will the nation swallow these recipes with quite as much innocent gusto. Celebrity chefs beware – the Cook Yourself Thin girls have tested your recipes and the results are pretty shocking. Tonight, Harry and Sophie come to the rescue of Lisa, a size 16 foodie who loves her celebrity chefs.

Her favourite fancy recipes may taste gorgeous but they aren’t helping her to shift the bulge. Can Harry and Sophie halve the calories but still match the chefs on flavour? They’ve got four weeks to help Lisa drop a dress size. Bangers and mash, spaghetti bolognaise, fish pie, roast lamb, trifle and sticky toffee pudding are all on the menu. Plus Sophie takes on top chef Jean-Christophe Novelli in a posh potato challenge and can Harry beat James Martin’s delicious chocolate brownies in a street taste test?

Tuesday 15th January 8PM on Channel 4