The four-part series will see the celebrities live and work on a farm in Hampshire for two weeks.
Widdcombe will be joined by Doctor Who star Peter Davison, Britain's Got Talent duo Stavros Flatley, The Only Way Is Essex star Gemma Collins, Good Morning Britain presenter Alison Hammond and I'm A Celebrity... Get Me Out Of Here winner Joe Pasquale.
The celebrities will go on a 15 day diet which will comprise of only natural foods grown on the farm.
This means waving goodbye to sugar, refined carbohydrates and processed food for the duration of the show.
Their new diet will be overseen by will see nutritionist Hala El-Shafie.
Ann Widdecombe is no stranger to reality TV.
In 2002, she took part in Celebrity Fit Club and, in 2010, she partnered with Anton du Beke on Strictly come dancing.
Sugar Free Farm returns to ITV in January.