The 35-year-old Love Actually star, who is set to marry her long-term boyfriend Jack McManus next year, is said to have been approached to film a fitness DVD - but she's being encouraged to put on weight to make the results look more dramatic.
A friend of the couple said: 'Martine and Jack are blissfully content and have been spending a lot of time together chilling on the sofa, basically eating what they want.
'Martine didn't set out to put on weight and feels as though she went to bed slim one night and, three months later, woke up huge.
'But now she is back in the limelight it has been made clear to her that a lucrative fitness DVD offer is on the cards. With her wedding to Jack next summer, she has already had a few concrete offers to launch a bridal slimming DVD.
'She even had one offer from a US company to become the face of some slimming pills but obviously she would never encourage irresponsible dieting.'
The friend added to British newspaper the Daily Mirror: 'At the moment the idea seems to be for Martine to eat whatever she fancies, possibly pile on a few more pounds, and then embark on a concerted weight loss regime.
'Apparently, the aim is to make the weight loss appear as dramatic as possible, taking her from a size 16 to a slim size 10.'