But the singer's unwavering dedication to her diet plan has hit a snag - with the stress of gay allegations about her father 'derailing' her efforts.
Jessica, who has lost 60lbs since the birth of daughter Maxwell back in May, is said to have lapsed from her Weight Watchers plan.
Looking good: Jessica Simpson in her Halloween costume just last week; but according to reports her diet plan has been 'derailed' by allegations her father is gay
'Jessica’s diet has been seriously derailed ever since the gay allegations against her father were released,' a source told RadarOnline.
'While she’s not diverting from the diet, Jessica isn’t sticking to the portion plan and isn’t losing as much weight as she should.
'She knows that as the Weight Watchers spokesperson she has to be more disciplined, but her emotions are all over the place right now.'
Allegations: Joe Simpson, seen last week, has split from his wife of 34 years amidst reports that he has come out as gay, which he denies
Her parents Tina and Joe revealed they had filed for divorce last week after 34 years of marriage.
Split: Joe and Tina Simpson last month filed for divorce after 34 years
Speculation has been swirling around Hollywood that Joe has been dating an aspiring male model.
But according to reports he has been trying to put an end to the rumours by telling friends and family that the speculation is 'absurd'.
A representative for the family has dismissed the reports as 'completely false'.
Jessica has not yet commented on the drama but a source tells People magazine: 'She's sad, but she's okay.'
Jessica's deal as the face of Weight Watchers is rumoured to be worth $3million.
Along with her dieting she also works out four times a week with celebrity trainer Harley Pasternak.
Pasternak recently told Us Weekly: 'In over 20 years, I've never seen as consistent of a weight loss.
'Jessica's right where she needs to be. She's gotten so much stronger.'
Before the weight loss: Jessica heading to the gym at the start of July; she has lost 60lbs on her diet plan to date