I try to keep below 1400 calories per day, and nothing with fat content over 5g, but that's my choice, not on the advice of my team (I can't remember what they said), and I am 10 months post op.
Initially, I just stuck with a 'healthy' diet made up of fruit and veg mostly, with as much protein as I could manage and as little carbs as possible, and lots and lots of water! Certainly that's what I would suggest for the first few months, you will soon settle into what works for you.
Rx