KIRSTIE ALLEY is gorging like there’s NO tomorrow . . .  

After triumphantly slimming down as she pursued the “Dancing with the Stars” trophy, the “Fat Actress” star has gone on a wild eating binge – and quickly packed on 12 pounds.

In startling new, the star looks every bit her jowly, plus-sized 60 years of age.

“No one expected her to keep up the demanding 2,000- calorie-a-day diet or grueling seven-hour dance sessions once the show was over, but Kirstie has returned to her bad old ways,” said a friend.

The devastating ‘Dancing’ loss – coupled with not having a man in her life – has left her miserable, according to her friend.

Kirstie, who’s been in New York, “has been consoling herself by eating the best food the Big Apple has to offer,” said her pal.

“She’s put on about 12 pounds since the ‘DWTS’ finale on May 24, and doesn’t show any signs of slowing down. Her body looks bloated, her face appears puffy and swollen – and the double chins have returned.

“Dance, exercise and dieting are still part of Kirstie’s daily life, but not nearly to the same degree as during the show. And not having a significant other has left her feeling sad and alone.”

Incredibly, a few weeks ago, Kirstie had been showcasing her slimmer look in body-hugging clothes and bragging about being down to a “stretchy size 4-6.”

But a stylist, who studied her appearance while she was competing, concluded: “Those claims she’s making about fitting into a size 6 – even a stretchy size 6 – are completely outlandish. Her dress size is closer to a 10 0r 12.”