Kell Brook has opened up about mental and physical torment he used to endure to make the 147lb welterweight limit ahead of his step up to middleweight.
And he admitted he would “probably” never fight at welterweight again, meaning he will no longer defend his IBF title.
The 30-year-old on Saturday fights for the first time at 160lbs, where he will challenge the feared Gennady Golovkin for his WBC and IBF middleweight titles at London’s 02 Arena.
He remains the significant underdog for the match-up between two undefeated world champions, but has a noticeably bigger build for the occasion.
At welterweight Brook often appeared to be fighting a losing battle to remain at 147lbs. On Saturday he will finally relish the build-up to the biggest fight of his career after the painful struggles of the past.
“It’s terrible. Fight week - when you’re that hungry you can’t sleep, you struggle to even walk to the weigh-in.
“There’s not even any fluid left in your eyeballs. You’re that drained, that tight it’s untrue. There’s nothing in your mouth; there’s nothing in you. It’s a miracle how I do make it. I’m talking that tight.
“Yeah, (your mind is) playing tricks. “
You’re always on and off the scales, going to the toilet, jumping back on the scales, having something to eat on the scales. Mentally, for weeks on end, it’s, ‘I’m not going to make this weight’.
“It drains you over a long period of time - ‘I’m not going to make it this time, I’m in with someone who’s going to be dangerous, I’m in a sport you can legally get killed in’. There’s so much on your mind for weeks on end, and it takes something out of you.
“I’d just want to get into a dark room and hide away.”
Brook’s confidence in his new physique and weight division should be placed into context. Saturday’s fight will not be for Golovkin’s WBA title.
The governing body has refused to sanction a title defence because the Briton has never fought at middleweight, even if his greater comfort suggests he sees a long-term future at closer to 160lbs.
Asked if he is likely to ever return to welterweight, Brook responded: “Probably not, but if we can and it makes sense, we will.
“I’m a weird character, I’d just get on with it, as hard as it is, because it’s all I know. But now I’ve had a taste of these meals and feeling how I feel, I don’t really want to go back to that horrible feeling.
“I’m very hydrated. As soon as I started moving (on Wednesday) I started sweating, I’ve had many meals.
“I feel strong; I feel like I’ve never felt before. I’ve grown and put muscle on. I’ve been draining myself to make 147 for years. I feel more natural, more comfortable at this weight.
“I’m going to be a monster, and surprise everybody when they see me and Golovkin at the weigh-in.”