If you are doing IF....eating low carb...and do have some sort of higher insulin response to a larger meal....the fasting hours with less insulin release should help balance the equation. Low carb eating will also prevent high blood sugar issues. Of course remember IF is supposed to be intermittent....so mix it up.
Plus if you are exercising you are also improving insulin sensitivity.
Honestly if you want definitive answers you could get your fasting insulin tested every month or so to see what is really going on.