Like Dumpling said, your body is one of the greatest gauges towards what you need. I’ve noticed that when I’m craving chocolate or other sweets, it’s just my body craving carbs and I have some fruit (or just ignore it when I’m eating low carb). I believe there are some tables on the interwebs where they explain the link between your craving and what your body probably needs, may want to have a look at it?

If you crave another fast day, sure, go for it! Just be careful you don’t do them too often 😉 You could also take your fast day menu and double everything, that way you do what Dumpling says (eating a food group you may be missing on non fast days) and you’re still on lower calories than when you’d be eating normally.