An excellent and balanced article on a number of diets (OK, 10 to be precise) and their strengths and weaknesses. Few are without merit completely but many have their claims exaggerated.
I’ve had success on the 5×2 mostly because it reduces the calorie intake overall, which is kind of how you lose weight. I have an unresearched suspicion that an awful lot of dieting works by focusing the mind on food and drink intake – while I was trying to reduce my weight a lot the rule was “eat normally on your non-fasting days” but of course I was more focused on what I was putting into my system even then.
The article is worth a read, partly because it debunks some faulty research but also because it treats neither the diets’ promoters nor their followers as idiots.