The 49-year-old Loose Women star announced she and her husband Nick Feeney would be cutting out various products from their everyday diet, including bread and alcohol.
She insisted she was watching what she eats for health reasons and not to lose weight or detox for January.
In a lengthy post shared on Facebook, Andrea McLean wrote: “So for reasons that will be explained, I have to go on a ‘gut cleanse’.
“Not a detox, or a weight loss for January thing, it’s to re-set a very poorly system that needs help.”
She continued: “There was absolutely no point starting this in December for very obvious reasons, so it made sense to begin in January when the rest of the world is a bit more forgiving towards someone having to cut lots of things out of their everyday diet.”
Revealing her husband has decided to support her by joining in, the TV star explained: “This has very nearly BROKEN US! Nick is very sportingly doing it with me, but he is struggling even more than me – probably because he doesn’t HAVE to do it!”
The television presenter went on to tell fans she would be using Facebook Live to update them on her progress.
Concluding, she finished: “Look out for timings here and on our website www.thisgirlisonfire.co.uk where we are HONEST about the reality of attempting something like this.
“What’s it really like? Is it worth it? Will Nick cave in? Will we survive? To be honest I’m too hungry to care right now – is that wrong?”
The message was accompanied by a video, which saw Andrea joking about the strain the cleanse has had on her marriage.
Turning the camera to Nick, Andrea could be heard teasing her spouse about the difficult lifestyle change.
Staring down at the floor, the businessman said: “I’m struggling,” before covering his mouth and adding: “I’m trying not to swear.”
Laughing in the background at her partner, Andrea continued to mock the managing director and founder of One Night Stand.
“Why don’t you cleanse and I just eat loads and we see what happens,” Nick offered.
Responding, the former weather girl screeched: ”This could break us if I have to do this on my own cause you said you would do it with me.”
Trying to assure her, Nick replied: “I will do it with you, but I may kill someone and eat them.”
Then, the couple burst into a fit of laughter, with Andrea recalling a shopping trip they had gone on prior to uploading the clip, where Nick joked about eating a man he saw on the street.
Andrea was introduced to Nick by a Loose Women make-up artist, who set them up on a blind date.
After two years of dating she announced she had moved in with the businessman in January 2016.
The pair tied the knot in November 2017, three years after dating and their nuptials were attended by celebrities including Stacey Solomon.