I find myself more often than not undereating on my workout days, as they usually correspond with work/school days as well. For this reason, on my rest days, I just eat and eat.
I think like Mike said, it really depends on how youre feeding during the other days, weither youre eating really clean, and enough, or if youre not eating enough, or not so clean.
Also, I think itd really depend on your goals. Are you trying to lose BF, or gain some of the benefits of fasting. I think if you wanted to lose weight, then keeping it clean and dialed in during the workout days, then fasting would be great. Just wouldnt want ya to be too gassed on your first workoutday cause you hadnt eaten enough those 3 days, and youre trying to workout fasted for longer than 24 hours.
But, I read an article that showed there was statistical decrease in performance of athletes who were fasted for 3 days, so, you should be okay either way I guess. Just dont know how comfortable that would be.
I dont think you need to compensate for lost calories on your fast days by eating more on your non. I think that would be counter productive, unless youre trying to gain weight.