By Elizabeth Leonard
May 18, 2009 12:00 PM

When Kirstie Alley stepped on the scale for the first time in 15 months, she had a hunch that it wouldn’t be pretty. “I thought I weighed 190, but I got on the scale and started screaming,” recalls Alley, sipping homemade cherry- and orange-infused water in the kitchen of her sprawling Hollywood Hills villa. “It said 228 lbs., which is my highest weight ever. I was so much more disgusting than I thought!”

But looking back, Alley, 58, is hardly shocked that her body—which she famously trimmed down to 145 lbs. after losing and keeping off 75 lbs. during her three-year stint as a Jenny Craig spokeswoman—had ballooned beyond 200 lbs. yet again. Since parting ways with Jenny Craig in December 2007, she has not worked out and even banished her gym equipment to the garage. As for her diet, her small, low-calorie portions gave way to Chinese takeout and pasta drenched in butter. “I fell off the horse. I actually fell off the Trojan horse!” says the 5’8″ star. “But your solution is either jump under the E train or you do it all again.”

Opting for the latter, Alley is primed to hire a trainer, toss the butter and sign up for a triathlon in order to whittle her “schlumpy” figure back down to a bikini-ready 140 lbs. “I’m going to have to work harder than last time,” says Alley, but “I’m way excited.” In a candid interview, Alley sat down with PEOPLE’s Elizabeth Leonard to talk about how she piled on the pounds and how she plans to get her body, confidence and—yes!—even her groove back. (Note to Jamie Foxx: She’s got her eye on you!)

Okay, how did this happen?

It started with New Year’s [2008], right after leaving Jenny Craig. When you’re a spokesperson for Jenny Craig, there’s responsibility. It’s very scrutinized. You have a person every week standing over you when you get on the scale, and I did it naked because those panties could weigh 30 lbs.! It was amazingly successful. But the first nail in the coffin was that I didn’t have to weigh in. I just sort of went wild. I thought, “Wow, here’s the first New Year’s where I don’t really have to be good because no one’s going to weigh me.” Ugh, that was the end of me!

Did you actually believe you’d keep all the weight off?

I did. I absolutely said, “I will never gain it back” and I 100 percent meant it. I also kept the weight off long enough that if you were a betting person, it shouldn’t have happened.

At what point did you realize you were really gaining it all back?

About 8 to 10 months after ending Jenny Craig, I had definitely succumbed. By then I was distraught. You loathe yourself. You hate what you’ve done to yourself. The first time I got really fat, it was a very different ride. I was having fun, baking cookies and spending a lot of time in Maine being supermom. That was not this occasion. This time I would say it had a darker side. Because there was a lot of self-hatred that was magnified because I’d let so many people down. All I thought was, “I’ve let all these people down and I’m humiliated.”

Did you go right back to indulging in cakes and pies the way you did the first time you let yourself go?

It wasn’t the exact same M.O. My food demons are Chinese food, sugar, butter. A lot of butter. If I’m at the movies, usually I eat popcorn without butter, but I’d say, “I’m at the movies, so who cares?” And toast with butter. Or let’s say I had two cups of pasta and six tablespoons of butter on it. There was a lot of butter going on.

What else would you eat?

For seven months I was a vegetarian, and I can’t tell you how much weight I gained being a vegetarian! A vegetarian would probably be eating vegetables. But to me being a vegetarian meant I’m going to eat enchiladas with no meat, and I’m going to eat lots of bread, lots of carbs.

What happened to calorie-counting?

Before, when I was on Jenny Craig, I would have an English muffin that’s 140 calories, and a tablespoon of organic strawberry jam and that’s 25 calories. I’d be conscious. But then I went unconscious. I wouldn’t even think! I’d be like, “Here’s my English muffin and, whew, I love butter!” For three years I was taught that this tablespoon of butter is 100 calories, but you make yourself stupid. You have to pretend that this time it’s not going to put on weight.

But it did and you started getting heavy …

I’m fat! There’s nothing else to call it. I know that a lot of people like to call it a “disease” and an “addiction,” but, honestly, the bottom line is that I was just really irresponsible.

What’s to blame for your weight gain this time around?

If you stop exercising—which I did—and if you stop watching your caloric intake—which I did—you’re gonna get fat. I was getting away with it for a while. The weight wasn’t coming on, like, by leaps and bounds. At first I was, like, “Look! I ate all that and I’m still wearing the same clothes!” Then when the clothes would get tight, I’d go, “Well, yeah, they’re sort of tight but, so what? That skirt was too stupidly skinny anyway.” Then I started justifying everything. If I’m gonna have 3,000 calories a day, I’m gonna justify “Oh, I’ll work out tomorrow.” But then I don’t.

Last time you gained weight, you drank 14 Stewart’s grape sodas a day. What was your must-have food this time around?

Probably butter. I think butter’s the thing I missed the most the whole time I was losing weight and maintaining. It wasn’t sugar this time. I’d say it was just fats, just icky fat. That’s why my body looks really different. I’m not bloaty.

Was there anything fun about getting heavier this time?

No. I’m not saying there was never a fun moment, but this was torture. It was sort of a tortured “loss.” Like I said, not having this job anymore of pied-pipering people through a weight-loss journey? It was just a loss. When I wasn’t doing Jenny Craig anymore, I guess I forgot I was an inspiration.

Now it seems as if you’re ready to be that inspiration again. Case in point, you’ve got exercise equipment in your living room.

That just got moved in. I had taken it out of the living room and put it in the garage because I decided that I needed to have people over for dinner parties! It’s circuit-training equipment. But I need a trainer because I won’t push myself. It’s the same thing with acting. I like to show off. If I have a trainer that I want to impress and show off for, I’ll pretty much do whatever it takes.

What weight do you want to get down to?

I have to be below 140 to really look good. I have to work my legs like crazy. Actually, do you want my real goal? My real goal’s always too low. I love the way I look at, like, 128. One time on Cheers, I weighed about 148 lbs., and they told me to lose, like, 20 lbs. Now, I’m 5’8″, so at 148 lbs., I wasn’t fat. But they’re saying, “You know, you need to lose 20 lbs.” So what does that put me at? 128. That’s where I keep getting this number.

Any other goals?

One of the things I want to do is do a triathlon. I’ve been researching it, and I might want to do my first triathlon in Italy. It’s a 2-mile swim, 12-mile bike and 3.5-mile run. I was a competitive swimmer, so I think the swimming will come back to me really fast. I don’t know about the bicycling. I mean, I left off with a Schwinn where you push back on the brake. That’s how far I’ve come on bicycles.

Aside from the triathlon, how do you plan on losing the weight this time around?

I am creating a weight-loss system that will end the roller-coaster ride. Details are completely under wraps.

How’s it going?

I have lost 20 lbs. so far.

So you have no doubt you can do it again?

Yeah! You know, I’m 58 years old. I’m the girl that when I’m 80 I want to look 60. When I’m 60 I want to look 40. I like the 20-year-younger look.

You don’t look 58 …

When I don’t have the weight on, I look a lot younger, and that drives me nuts. That’s enough motivation for me right there: The one thing that I think would catapult me into being thinner is vanity.

Are you self-conscious?

I’m totally inhibited. When I’m overweight I will not go out. With my closest friends, yeah. But you wouldn’t see me at a premiere.

How’s your dating life going?

I haven’t been having sex. I did have dates, but I think I’m worse than I ever was! I want a booty call with Jamie Foxx. For real. I’ve always had a bit of a thing for him.

Do you feel desirable when you’re overweight?

Do I feel desirable? If Jamie came over I would! Because I feel like he would understand the full-figured woman. I do.

How do your kids Lillie, 14, and True, 16, feel about your gaining weight?

It’s twofold. I think that they feel empathy for me when these ugly paparazzi pictures are out. But their view is sort of like, “Mom, somebody didn’t kidnap you and tie you down and stuff food in you.” They don’t think like, “Oh, poor Mom.” They get that it’s my responsibility, so that’s why I think that it’s sort of funny to them too.

Are you still ashamed that you’re heavy again?

I was. You have blame, shame and regret.

But you seem ready to turn your life around.

I’m ready to work. I messed up along the way, but I’m not going to concentrate on that. I’m gonna go, “You know what? Get back on the horse, lose the freakin’ weight, and then just move forward!”