FILE - In this Aug. 22, 2016, file photo, Jessica Alba, a cast member in "Mechanic: Resurrection," poses at the premiere of the film at the Arclight Hollywood in Los Angeles. Alba announced she was expecting her third child in an Instagram post on July 17, 2017. (Photo by Chris Pizzello/Invision/AP, File)

The 'Little Fockers' star has decided to have a cleanse before indulging in a festive feast over the holiday season and has turned to nutritionist Kimberly Snyder for a healthy menu.

Speaking on her Instagram Story, she said: "2 days into @kimberlysnyder Custom cleanse -and I'm feeling pretty ok ... This cleansing soup is next level (awesome). I needed a bit of a detox/reset before Xmas (sic)"

Jessica - who has three children, daughters Honor, 10, and Haven, seven, and 11-month-old son Hayes - is following a strict diet and has eliminated animal protein, dairy, alcohol and gluten from her menu as she re-balances her body.

The 'Sin City' star is starting each day with a "green smoothie" for breakfast, then having a "protein smoothie" for lunch and finishing off the day with her "yummy veggie soup" for dinner and is drinking "green juice" in between meals and lots of water to keep her energised and hydrated.

Jessica is determined to stick to this detox because her previous attempts to go on a cleanse have ended in failure.

She revealed: "Her challenge or rather my challenge is ... I've never been able to stick to a cleanse. If I last 5 days -w (with) slight modifications, I feel pretty good about that. Just being realistic".

As well as enjoying Christmas with her family, Jessica and Cash will also be celebrating their son Hayes' first birthday on New Year's Eve (31.12.18).