O'Donnell Tweeted side-by-side before and after photos of herself, revealing the almost 50 lbs. she's lost since last year, and the difference is remarkable.
"Almost 50 lbs. off – I can see it now," she wrote in the caption.
The actress and comedian, 52, had gastric sleeve surgery in July 2013, and has slowly been losing weight ever since.
"I did it to save my life," said O'Donnell, who suffered a life-threatening heart attack in 2012.
After the health scare, O'Donnell, who was 230 lbs., started a doctor-ordered exercise and diet plan – daily walks and reduced red meat, carbohydrates and sugar in her diet – but the pounds did not come off.
"She tried to lose weight on her own but it wasn't working," her spokesperson Cindi Berger told PEOPLE in February.
"It was a life saving surgery," Berger said. "But it's only a tool, not a cure."