>I figured it might more efficient on fasting days as it might help burn more of my fat reserves instead of using the recently eaten food
So I get why this makes sense, but step back for a moment and think about it. The body isn’t just some closed system that only operates on a 24 hour cycle. You’re reaching the same deficit regardless of when you workout.
Think about it stretched out to say a week. You ate X number of calories, your metabolism burned Y number, and your activity burned Z. It doesn’t matter when Z was during that week it all totals the same.
So just work out when it makes the most sense for you and your schedule.
It’s really up to your preference as to how you feel and what you like.
I do ADF and cardio every other day. I prefer to do it late in my fasting day, after I’m 24 hours or more into the fast. I may not be quite as energetic as I would be on an eating day, but I find the energy I have is really stable. No ups or downs.
I don’t know of any difference in “effectiveness.” I would go for what you prefer.