Lookin' good, Sarah Ferguson!

The Duchess of York, 55, showed off her more than 50-pound weight loss at the London premiere of 'The Theory of Everything' on Tuesday, Dec. 9.

Sarah, who was once referred to as "the Duchess of Pork" in British papers at the height of her weight issues, revealed she recently shed the excess pounds by cutting out sugar and adhering to a strict fitness regimen.

sarah ferguson weight loss

Sarah in 2013 (left) and 2014 (right). Photo Credit: Getty (2)

“Beatrice was an 8lb. 8oz. baby and I was only six pounds off my full-blown pregnancy weight,” she previously told 'Hello!' magazine, referring to her now 26-year-old daughter. “I decided to make a change.”

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The Duchess — whose high-profile marriage to Prince Andrew, the Duke of York ended in 1996 — once served as an ambassador for 'Weight Watchers.' But now, she has taken the reigns to help ensure she maintains a healthy weight going forward.

sarah ferguson & daughters
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Sarah with her daughters Beatrice and Eugenie in 2009.

Sarah and Andrew, 54 — who married in a lavish royal ceremony on July 23, 1986 at London's Westminster Abbey — are also parents to 24-year-old daughter Princess Eugenie of York. Prince Andrew is the third child of England's Queen Elizabeth II and Prince Philip, the Duke of Edinburgh.

'People' first reported the royal's weight loss news.