It's your body, of course. Feel free to stuff it, starve it, pierce it, sell it, euthanise it - I'm all for personal choice; whatever makes your happy, if you say it works for you then crack on and good luck. I can understand the point of some crashy-style weight loss regime in order to make a big impact - and then after which you still have to do the hard work to maintain your new superbody in perpetuity. Makes sense (though rarely happens). But a crashy-style weight-loss regime simply to tread water? To make-up for your 'bad' days?! I can't help feeling you're just pissing in the wind. And sooner or later your bladder will be empty. And it'll still be windy. It's not about living a uniform life or being 'bad' or 'good' - it's the simple maths of calories in and calories out - from today - to the day that you pop your clogs. Sustainability is everything. If anyone currently doing the 5:2 is still doing it in five years I'll eat my lo-calorie hat. They'll be on to the next fad regime. And if they're anything like my own diet-lovin' friends, they'll all be exactly the same size as they otherwise would have been, give or take a few pounds - only with a few less spaces on the bookshelf.