Jessica Simpson hates leaving her children to work out.

The 33-year-old star is desperate to lose the weight she put on after having children, Maxwell, 15 months and two-month-old Ace, but prefers to spend her time with them rather than going to the gym.

A source told the US edition of OK! magazine: ''She would rather play with her kids than work out. She feels really guilty whenever she leaves them.''

Jessica's fiancé, Eric Johnson, has tried to convince her to forget about losing weight and focus on enjoying motherhood.

The insider added: ''Eric is so happy with his family he doesn't care about the weight as much as Jessica does. He tells her to stop putting pressure on herself. He says they can work out together, cook together and then the weight will drop right off.''

After her first pregnancy - during which she gained 70 pounds - Jessica subsequently lost 50 of them by going on a Weight Watchers diet, which she says worked well for her and insists wasn't too strict.

She said at the time: ''I didn't need to be perfect to get here - to lose over 50lbs. It lets me be me, and I'm only human. I love food, I love life. I had no idea I could be so in control and so free at the same time.''