The 38-year-old star recently launched her new swimwear range for Next but didn't strip off to model the new collection.
Asked why, she said to UK newspaper Sunday Mirror: 'I didn't have time to work out at all for the campaign so if I look good then it's not down to working out.
'I'm a mum and I stuff chocolate like everyone else. I mean, if I know you've got to get into a bikini then I might go for a power walk but I just don't have the time these days to exercise like I used to.'
The star was also keeping quiet about the chances she will become an X Factor judge if Simon Cowell and Cheryl Cole move to the US.
She said: 'You're going to have to wait and see. I think Simon Cowell would be the first to know the answer to that.'