Interesitng you say that as I am always a firm believer in that sometimes you have to listen to your body. I was training for an ultra a few years ago and after my Friday long run (I detest running on a weekend) of about 5-6 hours I would crave Coke (which I never drink ordinarily) and salt and vinegar crisps - and I mean a craving like I have never had for anything else. I guess my body was telling me I needed more sugar and salt.