The Melissa and Joey star, 36, told PEOPLE on Saturday she's dropped two dress sizes since giving birth in September to her third son, Tucker McFadden.
"I get compliments from my friends and family and coworkers," says Hart, who is about to start raising money on Kickstarter for the movie Dorothy's Walk of Shame. "I've gone down two jean sizes. It's been really great."
The actress credits her weight loss to Nutrisystem, for which she is a paid spokesperson.
Hart, who says she's "done a lot of different diets," also credits her hubby, Mark Wilkerson, for helping her shed some pounds.
"My husband is really into fitness, and I've always been big into working out," she says. "He's very supportive and gets me out for runs here and there to keep me active. My boys keep me active as it is."