I do a powerlifting routine and sometimes work out while fasted (16+ hours). Doesn't make a difference to me to be honest but I haven't tried a 24hr or multi day fast. However, my lifts are quite sensitive to sleep patterns and if I'm not well rested my lifts can suffer 5% or so (15% seems pretty large? That's a 45lb difference on a 300lb squat!).
I am not super strict with when I eat, make sure I get enough. But I agree that my lifts suffer more if I haven't given myself enough rest or time between workouts - that's a bigger detriment to lifting.
