DESPITE her re­newed gig with Jenny Craig, Kirstie Alley is having a tough time shedding pounds this time around – and a source says she’s blaming her weight woes on her lackluster love life!

The 63-year-old star hasn’t had a serious boyfriend since splitting from actor James Wilder in 2000, and a pal says with no prospects on the romantic front, she’s afraid she won’t be able to repeat her past weight-loss success. In her last go-around as a Jenny Craig spokesperson, the “Fat Ac­tress” dropped a whopping 75 pounds.

“That was 10 years ago and Kirstie was in her early 50s,” a friend told The ENQUIRER. “She still had hopes of finding her dream guy that she could marry and spend the rest of her life with.

“Now, she’s just de­pressed. She doesn’t think a 63-year-old woman is going to find anyone, no matter how much she slims down.”

Kirstie was a bona fide sex symbol in the 1980s while playing bar manager Re­becca Howe on “Cheers.”

 She claims that early menopause in 1992 trig­gered the body changes that caused her weight to explode.

Kirstie weighed 210 pounds when she first joined Jenny Craig in 2004, and while the diet helped her whittle her figure down to 145 pounds, she backslid after cutting ties with the program in 2007. Sources say she hit a high of more than 260 before shedding 100 pounds in 2011. But her weight is once again creeping up.

She’s hoping that teaming up with Jenny Craig again will help her lose 30 pounds, but our source says she’s having a tough time staying mo­tivated.

“Her metabolism has slowed as she’s gotten older, and she no lon­ger sees a brass ring at the end – finding the right guy,” explained the friend. “She’s had a few dates off and on in the past 14 years, but noth­ing ever came of them.

“Kirstie no longer be­lieves there’s a romantic future for her, and friends fear it’s going to make her throw in the towel in battling her weight prob­lems.”