From PEOPLE Magazine Click to enlarge
Of course Nicole Eggert knew she was gaining weight. There were the clothes that no longer fit, so she ended up "living in sweats for eight or nine months–I could sleep in them and also walk out of the house in them." There were the nearly two years she spent not exercising, preferring instead to "just lie on the couch, rotting." And there were the fast–food joints she had on speed dial–the more deep–fried the meal, the better. "It was," she admits, "disgusting."

And yet it wasn't until last September, during a trip to the supermarket near her Los Angeles home, that Eggert realized she had become, in her words, "the fat girl." Standing in the checkout line, she noticed a magazine cover mocking celebrity bodies; focusing on one image, she said to herself, "'I have a bathing suit like that,'" she recalls. "And then I saw the word Baywatch! And I went, 'Oh my God.'"

Eggert, 38, grabbed the magazine, "threw it facedown on the conveyer belt and was just like, 'Get me out of here!'" When she could finally look at the shot of her bikini–clad self–taken last August at a friend's pool party when "I was just hanging out, unaware I was being photographed," she says–the actress knew she could no longer ignore what had happened to her once–size–2 frame. "It was a good slap on the head for me," she says. "I didn't even recognize myself!"

Some four months–and a lot of salads and hiking–later, the 5'2" Eggert has shed at least 15 lbs. (she didn't own a scale) to get back into her 26–waist jeans. Most important, for the first time in her career–which took off in 1987 when the then–15–year–old starred opposite Scott Baio on the sitcom Charles in Charge–she lost weight the healthy (and hard!) way: by committing to diet and exercise. "When I was younger, if my belly was sticking out, I'd skip lunch and be skinny again," she says. "I never had to worry about my weight."

That changed with her 1992 arrival on Baywatch, which heralded her transformation from the girl next door to a full–blown sex symbol–and one who dated fellow '80s teen idol Corey Haim and also her Charles costar Baio. Being in a bathing suit all day long "made me aware of what I was eating," Eggert says. She also was no longer a teenager, which meant that "I started to put on weight; it showed up in my thighs a little bit." Unaware of how to take care of her body in a healthy way, Eggert developed "my way of losing weight," she says. "Starve yourself and work out really hard."

Eggert cleaned up her act in 1998 when she was pregnant with her daughter Dilyn, now 11. (Dilyn's father is an ex–boyfriend of Eggert's; he is not in his daughter's life.) "I ate fruits and vegetables and a lot of salads," says the actress, who snapped back into bikini shape in no time. But in 2007 she lost her beloved father to cancer and sank into a deep depression. "I couldn't get up and cook, so I ordered," she says. "Whatever my daughter wanted to eat, I'd eat too–chili burgers, deep–fried tofu. That was the killer."

As the pounds piled on, Eggert says she mastered the art of self–delusion. "I always think I look better than I do!" she says; in fact, when she saw that unflattering bathing suit shot while standing in the supermarket checkout line, her first thought was, "'Did they Photoshop these, or do I really look like this?'" she says. "It's not until you look at yourself on film where you're like, 'Whoa!'"

As freaked out as she may have been by the changes to her body, Eggert decided that if others were going to mock her, she'd join in the fun by spoofing her body in a video for FunnyorDie.com. It ended up generating almost 1 million hits. "It's like what I tell my daughter: The way to get through [a bad situation] is with a sense of humor," Eggert says.

Four months later–and with some help from the pros on the new season of VH–1's Celebrity Fit Club, in which she is starring–her body is no longer a laughing matter. After overhauling her eating habits and revving up her exercise routine (see box for details), the actress is "in the best shape of my life," she says. "I'm totally motivated."

She'd better be; after all, as Eggert admits, sticking to her new fitness regime has proved a challenge. "I miss actually cutting something and chewing!" she says. But as is evident from a peek inside the actress's bathroom–where, for the first time, she has a scale–Eggert is determined to make sure the weight she worked so hard to lose doesn't come creeping back on. "I feel really proud of myself because I did it the healthy way," she says. "And I don't ever want to go back there again!"