Since zero food consumption improves clarity of thought [citation needed; not Woo please], I also got many things done on the product-management side.
It's actually not a new invention, fasting for clearer thought. I've been researching it because I have gone overweight due to lifestyle (not to obese levels, but enough to not enjoying it), and I wanted to find a way to reset. The clearer thoughts would be a bonus, but I won't get my hopes up there :). The problem with increasing exercise to address overweight is that it doesn't really help much long term, it is better to start such a regime when being slim (also less weight related damage).
Fasting is effectively forcing the body to switch to a mode we don't use much because we no longer have to forage for food (survival mode). It is best done with medical assistance, and you have to keep up liquids and minerals but avoid anything sugary, including fruit.
However, be aware that the first days are not going to be pleasant for you as well as your environment (someone mentioned your breath - that's just one of the side effects), and your temper will suffer too although probably would notice that with New Yorkers (I'm sure there are UK equivalents). After that it'll be OK, with one major caveat: your body will tell you when your fast is done (return of appetite and other fairly abrupt signals), and you should then restart eating (small at first, of course).
If this is a "fad", it is only because some marketing type may have wrapped a barrel of hype around it, but the idea is FAR from new. There's also a reasonable body of research available on it. I can imagine health clubs don't go for it because there's little money to be made from (temporarily) bad tempered people who only drink water with some minerals added..
Biting the hand that feeds IT
