I lost 3lb! 
I also noticed I ate better on the other days in general, more veg etc and more water in general
So - I'm giving this a go for real! Tuesdays and thursdays are my fast days. Last tuesday (hadn't planned for it at all ) I ended up eating 2 x crusty roll with basic fillings. Thursday I had a chicken breast sliced with fajita spice, and sauted spring greens and carrots - which was delicious!
On fast days I'm aiming for around 500 calories, but I don't sweat it if it goes a little over ... think one day last week was about 550.
I'll post my fast day meals and any weightloss (hopefully!)