Instead of IF sometimes I'll hold off eating anything until later in the afternoon. I've found that this helps with energy and concentration if I have a particularly stressful task in the morning like a research paper to work on or if its "reply to the 300 emails I missed while I was on vacation" day. Some days I will wake up and instinctively know that if I were to have anything besides black coffee, I'd just be in a daze all day long.
1) eat real food - more vegetables, moderate meat, moderate fruits, less grains, less sugar, less vegetable oils.
2) exercise - moderate intensity cardio, sprinting, heavy lifting, dedicated stretching and mobility.
3) live - relax, de-stress, meditate.
Disclaimer: I'm not professionally qualified to make any formal recommendations. I've just done my homework and I'm my own guinea pig. All of my data, unless otherwise cited, comes from a sample size of n=1 (me).