Rosie O'Donnell (WENN.COM file photo)

Rosie O'Donnell has dropped 12 pounds in a major health overhaul since suffering a heart attack in August.

After the actress' partner Michelle Rounds was diagnosed with rare cancer-like desmoid tumours in June, O'Donnell began indulging in a fattening diet of pizza and sweets to calm her nerves and she eventually tipped the scale at 234 pounds, her highest weight ever.

Weeks later the Now and Then star went into cardiac arrest, and the 50 year old reveals it was the wake-up call she needed to get her act together if she wanted to watch her five children grow up.

She tells People magazine, "I had a really sedentary lifestyle and that's deadly... It took a heart attack for me to learn to take care of myself... Now I feel like I've been given a second chance at life."

O'Donnell then tossed out all her junk food and insists she is already feeling better.

She adds, "Those foods almost killed me... I used to be tired and sluggish after I ate. Now I feel full, but lighter, and I have more energy."