The 30 year-old prepares to move up the necessary poundage to face Gennady Golovkin on September 10 but goes into the fight a huge underdog to knock the Kazakh from his lofty perch.
Despite early claims of a mismatch in some quarters, Brook is adamant that he can be even more effective when not being forced to shed weight and aims to prove it at the O2 Arena in the autumn.
“You ask my sparring partners about when I come into training at 160. I’m a beast, I’m a different animal,” Brook told Sky Sports News HQ.
“What it takes for me to get down to 147 is really, really hard and anyone who knows me will tell you. I’m going to be eating very well in this camp. I’m going to be fuelled for the training sessions and be able to push myself even more.
“In this fight, I’m going to shock a lot of people. I’m going to be bigger than Golovkin. Already my strength is proving unbelievable and we’ve still got man more weeks to go. I’ll be frightening by fight night.”
On his motivation for accepting the Golovkin fight, Brook added: “I want to do what the greats have done in past history.
“I want to be involved in the best fights out there and you don’t get much better than GGG. He’s a middleweight with all the belts on the line and I can’t wait for that.
“I can’t wait to test myself at these higher weights as I’m a different kid at these weights. So healthy, so fit and so strong and to levels I’ve not even reached before. Even I’m excited to see what I can do because we know in training before we have to strip ourselves down to make that lower weight of 147.
“We are coming up now and we are going to shock the world on the 10th of September,” promised Brook.