But surely, I hear you say, that’s crash dieting and crash dieting always fails? You end up putting back on all the weight you lost, and more. Well, no. Like anything, it depends on how it is done. Done badly, a very low-calorie diet will cause misery. Done properly, rapid weight loss is an extremely effective way to shed fat, combat blood sugar problems, reverse type 2 diabetes, perhaps even cure it.

- Michael Mosley