05/09/2014 at 02:00 PM EDT
has been making some serious lifestyle changes and they're paying off.
The former talk show host, 52, underwent gastric sleeve surgery
last July, and recently tweeted a picture
of herself with the caption "Almost 50 lbs. off – I can see it now."
But O'Donnell confesses that eating right is still a daily struggle.
"I read in a magazine article that sugar is eight times more addictive than heroin," she told PEOPLE on Thursday at a screening of her new HBO documentary The (Dead Mothers) Club
. "Because of giving up sugar, I walk past one of those kiosks selling newspapers and I'm like, 'There's the Swedish Fish. They're right there.' Almost like how alcoholics can't go into a bar. They want to grab the bottle, I want to do that with the Swedish Fish."
O'Donnell, who suffered a life-threatening heart attack
in 2012, said her goal is to be "totally heart healthy," explaining, "It means to be a certain weight that doesn't put stress on your heart. To exercise every day, to be aware of your blood pressure, and all of your heart stats."
She added: "I feel a lot better. I got very scared when I had a heart attack and they told me I really should not have survived it. It changed a lot of things for me. The way I look at the world, and the way I look at my own health. I can't ignore it anymore."