Sheridan, who plays the narrator in Joseph and the Technicolour Dreamcoat, shared her weight loss journey with before and after pictures on Instagram, reports dailymail.co.uk.
"I'm not one for weight loss regimes as I think everyone should be comfortable in their own skin.
'But comparing today's pic to day 1 of rehearsals on Joseph musical... I have lost 2 stone," she wrote.
The drastic weight loss of the "The Royle Family" actress has left her fans surprised.
One user commented:" Wow, what a difference."
Another one wrote: " Omg! gorgeous."