The 60 year-old actress has battled with her weight over the years and is an infamous yo-yo dieter.
But Alley says she feels better than ever and is proud of what she has achieved.
“I’ve lost 100 pounds,” she told Entertainment Tonight.
“I feel like I’m back in my element. I honestly didn’t even realise what I looked like.”
Alley appeared on the catwalk for Malaysian designer Zang Toi during New York Fashion Week on Tuesday night and said that she is now wearing the smaller version of his designs.
“Before Dancing With The Stars, I bought these dresses from size 14 to four,” she said.
“[They were] all the same dress, and I said, ‘You know what I really want? I really wanna be in this dress in a four!”
Although Alley is happy with her transformation, she says she will not be adding to her new look by going under the knife.
“I haven’t had plastic but here’s the reason; People do plastic surgery to make you look younger,” she said.
“I don’t think it makes you look younger. I think it can make you look weirder.”
Newswarped definitely agrees with Kirstie on that one.