For the better part of 20 years, I've been eating just one big meal a day, in the evening. (No good reason - it just sort of happened.) So, technically, most of my rides are fasted, as I have slept overnight and not had any food the day of the ride.
Shorter intense rides, like 30 miles, are fine - even if I go out 18-20 hours after my last meal. I've done a few metrics (100K) without calories. For anything much longer, or especially rides in the heat, I do notice some losses in performance if I am not consuming calories during the ride.
Since I've effectively screwed up my metabolism, I handle longer rides by eating a lot the day before and replacing calories through sources that are easier to digest - primarily liquids. I've done centuries without solid food, but not without calories!