'I'd love to lose a few more pounds, but I'm not dieting for my wedding,' she says. 'I'm not even doing Weight Watchers at the moment.'
Instead, the 22-year-old WAG is taking a healthier approach to getting fit.
'I'm eating really healthily, drinking plenty of water and going to the gym a lot more, maybe 3 or 4 times a week. I can really feel myself toning up,' she says.
But Coleen is keeping tight-lipped about the actual ceremony, thought to be on 12 June in the Mediterranean.
'All I'll say is that almost everything you've read in the papers so far is rubbish,' she says. 'My friends and family know the plans, but they're very good at keeping secrets.
'I can't wait to be Mrs Rooney!' she adds.
Coleen and Wayne, both 22, have been dating since they were 17.
Not all celebs refuse to diet. Find out how the others (like Catherine Zeta Jones, Martine McCutcheon and Jennifer Aniston) stay in shape with our celebrity diet secrets article.