My (limited) understanding implies this kind of thing is unhealthy and leads to suboptimal mental functioning.

If there's any unhealthiness to it, I didn't notice. It seemed to work out fine with my fencing & Taekwondo.

But mental functioning I really don't know. I ate pretty healthily even in the binging phase, but I know from my N-backing and polyphasic sleep experiments that one can be utterly unaware of even large deficits (or surpluses), and I was using no mental benchmark or task back then, so I would have remained unaware.