5:2 certainly works as it gives a calorie deficit, however I personally feel happiest on Mon/Wed/Fri Down Days, the remainder eat normally. There are lots of ways to do it, but they all aim for a calorie deficit. 5:2 was actually a plan for health NOT weight loss as featured in the Horizon Programme in July...weight was lost by the Presenter as a result however this was not the aim of the plan, whereas Dr Johnsons alternate day diet is designed for weight loss but does also have health benefits!