Jessica Simpson is "determined" and "excited" to lose her baby weight

A confidant told Us Weekly: "As soon as Jessica heals from the C-section, she is extremely determined to get back in the gym and work out. She wants to show the world and is excited to do it."

Since announcing that she and her fiance Eric Johnson were expecting their first child October 31, the 31-year-old singer has been under scrutiny over her pregnancy weight gain.

Now, the 5ft 3in TV star, who admitted to weighing 170 pounds when she posed nude and pregnant for the April issue of Elle, needs to slim down over the next few months to fulfill her contractual obligations.

She admitted to experiencing junk-food pregnancy cravings for snacks including Laffy Taffy, buttered Pop Tarts, and Kraft macaroni & cheese with Lawry's seasoning salt.

A source familiar with the diet plan company's negotiations revealed the stakes are high for their agreement.

The source said: "She'll have to meet the weight-loss goals for the deal to go through. She hasn't chosen a trainer yet.

"In fact, she hasn't even thought about working out for a year. But if she wants this, she'll need to work out a good five times a week."