In Hunter x Hunter, at first Knov's appearance was pretty bold and looked smart. But after knowing the fact that their enemies are stronger then he got scared.
First change: His hair got white and he was a little bit skinny.
Second change: Hair loss and lack of physical fitness.
But being a Hunter, why he undergoes such a huge change in appearance? I mean how come his whole physical body changed? They knew that the mission they are going into is really scary, but what was the reason behind his complete change?