More than three months after giving birth, Jessica Simpson is still struggling to slim down her post-baby body. And she knows exactly why.

“I let myself indulge in everything I wanted because it was the first time I was ever pregnant,” Simpson, 32 — who welcomed daughter Maxwell Drew on May 1 with fiance Eric Johnson — told USA Today. “I wanted to enjoy it.”

But now the singer-actress-fashion-designer is paying the price.

“I didn’t realize [the weight] didn’t all come off with the baby,” explained Simpson.

The Weight Watchers spokeswoman is sticking to a strict diet — forgoing her favorite comfort food, mac and cheese — and hardcore cardio sweat sessions. Simpson also takes time off from mommy duty to work with trainer to the stars Harley Pasternak four or five times a week.

jessica simpson heads to the gym

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While she has shed pounds each week, her waistline isn’t where she’d like it to be. Still, Simpson will begin appearing in ads for the famous weight-loss program next week.

“I’m not a supermodel,” admits Simpson. “My body is not bouncing back like a supermodel. I’m just your everyday woman who is trying to feel good and be healthy for her daughter, her fiance and herself.”

Do you think Simpson will get her body back? Weigh in below.