Kirstie Alley and Valerie Bertinelli
Brian Doben, Stephen Danelian
05/06/2009 at 04:00 PM EDT
When Kirstie Alley spotted Valerie Bertinelli's killer bikini body
on a recent cover of PEOPLE, "it blew my mind!," the TV star says. "She didn't just look good – she looked stunning! It was inspiring."
And a little ironic for Alley, who confesses to PEOPLE that she has put on 83 lbs
. Once a spokeswoman for Jenny Craig, Alley, 58, actually helped bring Bertinelli, 49, on board as a new face for the company in March 2007.
"It’s like the student surpassed the teacher, who is now over there in the corner, fat!” says Alley.
Nonsense, Bertinelli tells PEOPLE. Alley's weight gain "is just a bump in the road. Nothing in life goes smoothly all the time," Bertinelli says. She still considers her fellow actor "a mentor and a motivator. She's part of the reason I've come this far."
Now Bertinelli is more than happy to return the favor. "She should come work out with me!" says Bertinelli. "She should remember you can't do everything in one day [and] her exercise has to be consistent. She can do this. There's no doubt in my mind."
What's important to remember, cautions Bertinelli, is that the weight battle is a lifelong process. "I'm still on the journey and still keeping my fingers crossed," says Bertinelli. "I am one jalapeño pepper away from gaining 40 pounds. It's not simple! It's something you work on every day."
For more on Kirstie's journey from slim to "schlumpy" – including her comments on her kids, her sex life and how she plans to lose the pounds – pick up the new issue of PEOPLE, on newsstands FridayShare your comments here