That's like 15% of his bodyweight. That's a solid sized heavyweight (240ish) making the 205 weight limit. That's just about the most extreme I've ever seen.
I think a cut of around 8-9% of body weight is considered a normal healthy cut. Obviously, some guys can healthily cut a little more. I have seen fighters routinely pack on 10-20 pounds after a weigh-in & before a fight. But that was all before the new UFC USADA drug policy that included an IV ban. Which means 99% of the time fighters can now no longer rehydrate using an IV after a weigh-in.