From PEOPLE Magazine Click to enlarge
Melissa Joan Hart can still picture the "horrifying" moment in 2005 when, while pregnant with her first child, she was shaving her legs "and I looked down and I had tons of cellulite around my knees!" she says. Having gained 55 lbs. and getting up to 170 lbs. on her 5'2" frame, "I knew I was huge," Hart admits. "But that was crazy."

Still even that discovery wasn't as devastating as what she went through last June, when unflattering bathing-suit shots-taken only three months after Hart, then about 155 lbs., gave birth to her second son-led to cruel Internet attacks about her body. (One blog went so far as to blast her for "giving pregnancy a bad name.") "I still read blogs about me discussing how fat I've become," she says. "Everyone still thinks I'm huge. But I'm not anymore!"

While it's true that one look at the actress's new, 113-lb. bikini body leaves no doubt she is "in the best shape of my life," as she puts it, Hart understands the confusion. After all, the public has grown accustomed to seeing celebs (like Hart's close friend, My Name Is Earl star Jaime Pressly) back in their skinny jeans a scant six weeks post-pregnancy. "There are enormous pressures put on you in Hollywood," she says. In fact when Hart returned to the audition circuit after her first son was born, "everyone kept asking, 'How does she look? Is she fat?' Everyone wanted me to dance for them and show my behind-they literally wanted to see how big my behind was! It was horrifying."

Hart says that experience "motivated me" to hit the gym, and she was back in shape in about 10 months. (The hard work paid off, as she booked two TV movies, including Holiday in Handcuffs.) The second time around, however, reclaiming her slim figure (she had some 35 lbs. to lose) took her 14 months and "a lot of effort," she admits. "It didn't happen by magic-it was as hard for me as it would be for anyone else." Especially because she refused to commit to the 4:30 a.m. workouts that had kept her trim during her teen years on the hit shows Clarissa Explains It All and Sabrina, the Teenage Witch. "I didn't want to take any time away from spending it with my sons," she explains.

Instead she tried to lose weight beginning last April by first getting rid of all the candy she'd stashed in the 5,000-sq.-ft. Los Angeles home that she shares with husband Mark Wilkerson, 32, lead singer for the band Course of Nature, and their sons Mason, 3, and Braydon, 14 months. When that hadn't done the trick, she continued to slash various foods from her diet: bread, pasta, rice, potatoes. Not surprisingly, "I kept losing my willpower," she says. "It's really hard for me to say 'no' to something, whether it's a cupcake at a party or popcorn at the movies."

By January, despite her efforts, she still couldn't fit into her pre-baby jeans. "It was hard for her to accept that she'd had two kids and her body doesn't respond the way it used to," Wilkerson says. But Hart wasn't ready to give up, especially with her 33rd birthday looming. "I thought, 'Losing weight will only get harder as I get older, so I better do it now,'" she says. "I wanted to prove to myself I could do it."

Hart admits she was "lucky" to be able to consult both a nutritionist and a trainer (see box), but says that her biggest inspiration came from the women around her-including Pressly, who has a son, Dezi, 2, as well as her own mom, Paula, 53, who gave birth to seven children "and is tiny!" Hart says. "I realized I don't have to be heavy just because I have kids." Adds Pressly: "She finally took time to take care of herself. I'm blown away by how amazing she looks."

Hart admits to being impressed with herself as well. "I never thought I'd pose in a bikini again!" she says, noting that her last scantily clad photo shoot was a decade ago. (See "Growing Up in Public" on the previous page.) "To do it two kids and 10 years later? I'm so proud!"

What would make her even prouder, however, is if-after all her hard work-she maintains her svelte figure. "My biggest fear is that I'm going to blow it again," admits Hart. "It's always going to be a struggle for me, and I'm not fooling myself."

To stay on track Hart allows herself the occasional treat-like chips and guacamole, or frozen yogurt-so she doesn't feel too deprived. She also has set up a series of short-term goals, like fitting into a "pretty dress and looking great" for the May 30 opening of her Sherman Oaks, Calif., candy store SweetHarts. Yep: a candy store! Won't that be a problem for Hart? "No, actually," she says. "I love having a candy store because it reminds me of childhood. The only thing I plan to eat there is the nonfat frozen yogurt."

And even if a few pounds do creep back on, Hart-who says she and Wilkerson plan to have more children-finally feels at peace with her body. "I have a wonderful career, an amazing husband and two beautiful sons," she says. "I can't really complain about my thighs!"

Watch Melissa Joan Hart talk about her bikini bod at people.com/hart-video