Jessica Simpson's children have helped her lose weight.

The 33-year-old singer - who has 19-month-old daughter Maxwell and five-month-old son Ace with her fiancé Eric Johnson - hasn't struggled to shed her baby weight because her toddlers keep her on her feet all day long.

She told USA Today: ''With both kids I'm running up and down my stairs a million times. Eric and I go on walks together. I try and walk about four miles a day consistently. It makes me feel better.''

The blonde bombshell also has a personal chef to cook her healthy, low-calorie meals and works out with personal trainer Harley Pasternak four hours a week.

Jessica constantly battles with media criticism over her weight and forces herself to ignore negative comments.

She sighed: ''It does get old having people harping on how much you weigh or your body after pregnancy. People are going to pick me apart no matter what I do. I'm always going to have critics.''

The bubbly star stays positive by spending time with her family, and despite having her children so close together, she wouldn't rule out the possibility of expanding her brood in the near future.

Jessica added: ''Every day we don't know what's going to happen. They definitely keep our lives busy but full of smiles. We laugh a lot ... I would never say never [to more kids].''