I did a search and found this awesome article and thought I'd share it with everyone that is struggling with inner demons (ha ha)
Here it is -
Why Your Willpower is Like a Muscle - And How To Use It http://www.willpowered.co/learn/willpower-is-a-muscle
It seems that my willpower "muscle" is well tired by the time dinner comes round which is why I'm not sticking to the 500 cal limit for 5:2 - instead what I've been doing is a fasting window of 17 hours and then a massive binge of calories every day.
@Sassy1I'm still trying to work out why I do this. I am a very disciplined person: I go to the gym and knock out 16 km on the bike 3 times a week and of course do the fasting too....I hope this is a blip that will go away once my work situation becomes clearer/stable.