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Kirstie Alley has her ups and downs just like the rest of us.

The actress opened up about her fluctuating weight in a candid new interview with PEOPLE.

Alley's no stranger to diets -- she lost 50-lbs with Jenny Craig last year and 75-lbs when she was a spokesperson for the brand from 2004-2007.

Nevertheless, the weight always seemed to creep back on. "It's not in my nature to plan," the 65-year-old told the mag. "I'm a very spontaneous person, and that's how I got fat."

Of course, it's easier to pack on the pounds when you're constantly on the go, especially "if you travel a lot and you're wined and dined and you love holidays."

"I always joked that my holidays lasted from Halloween to New Year's Eve, and maybe even into Valentines Day," she confessed. "I would think it was okay for me to eat whatever I wanted during those months."

Even though Kirstie found reasons to justify her eating habits, at the end of the day, she knew her lifestyle wasn't exactly healthy.

"It was very social and joyous, like, 'I'm going to have a big Halloween party and have caramel apples,' but then I realized, 'Wow, that's your real trap zone,'" she explained. "So I still do the holiday thing, but I've learned something that wasn't in my vocabulary before, and that's a little bit of 'discipline.'"

The "Cheers" actress says she wouldn't have been able to keep her weight off if it wasn't for her long-standing partnership with Jenny Craig.

"I love doing Jenny Craig and being their spokesperson," she said. "I'm not exaggerating when I say my consultant is my lifesaver! She has taught me how to maintain my weight fairly effortlessly."

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