Blake Lively cut gluten and soy from her diet in order to drop her baby weight in time for her role in 'The Shallows'.

The 28-year-old actress - who gave birth to her first child James in December 2014 - had to re-evaluate her diet and cut out all ''processed foods'' for the drama film, which sees her spend the majority of the scenes sporting a skimpy bikini.

Speaking on Australia's 'Kyle and Jackie O Show', she said: ''What we actually did was no gluten and no soy. It seems like it was really easy to cut out but you realise there is soy in everything... Even if it's healthy wholefoods or organic stuff there's always soy in it. But once you remove soy you realise you are eating just like no processed foods. That's basically what I did. No processed foods and then working out.''

And, although it was hard work, the blonde beauty - who is currently pregnant with her second child - believes she was in the ''best shape'' she's ever been in while shooting the film.

She explained: ''I was ready to get back in shape but I've never been in that good of shape in my whole life,' she said. To do it after having a kid is actually really nice because you see your body after having a kid and it's beautiful because you just gave birth but you're like, 'Oh my God this is not what my body looked like.' ''