I run fasted most days but long runs can be tough. I’m at the end of a training cycle and realized I haven’t practiced eating mid run so now I’m a bit leery to try it race day even though it would probably improve my performance.
I don’t think a small amount of calories on long run days mid run will throw off your training and you should definitely practice if you will be incorporating into your race day routine.
My next training cycle I am even thinking of experimenting with some pre run nutrition. I am OMAD and typically eat around noon anyway so I will just have a longer window on long run days.