The actress, who is five months pregnant with her first child with boyfriend Thom Evans, explained that she can't wait to get bigger.
She told Hello: "It takes some getting used to. I would like it to show more actually. At the moment I just look as if I have eaten a big bowl of pasta.
"I'm looking forward to looking like a huge whale in a couple of months."
However, the Piranha 3D star admitted that she doesn't want to "overindulge".
She added: "I haven't been exercising at all so far. But I am always running around and I do a lot of gardening.
"I haven't been eating for two though. As long as I don't overindulge, I should be able to get back in shape quite quickly."
Brook also said that Evans has been appreciative of her new figure.
She explained: "He especially likes the boobs. He says I look hotter now. But I think he is weird."