Weight / Fat loss

I normally have a pretty good and controlled diet (not monastic, but quite considered with regards to what i eat), and I think on Friday I end up just getting bored and wanting slightly more junky stuff.

Heh, understand that too well. A lot of strength training folk are into "cheat days", where they eat what the hell they like one day a week and rely on their regular routine and regimen to keep it under control. Some people say it actually helps weight loss because it stops your metabolism from adapting to your reduced intake and effectively becoming more efficient. I think that may be an entirely unscientific excuse but it beats going crazy from boredom and deprivation.