Star has two quite unflattering stories about Jessica Simpson this week. The cover of the gossip rag has an inset photo of Simpson in the lower right corner and says “Jessica Simpson: It’s Not a Fat Suit!” The accompanying story details Simpson’s estimated 25 pound weight gain since her super-fit days as Daisy Duke in early 2004. She didn’t perform with the Pussycat Dolls on May 4th and just hosted, Star claims, because she didn’t want to “squeeze into a revealing outfit” like the Dolls.

She could lose weight, though, they say, for an upcoming role as a Marine in Major Movie Star. Jess has gained weight, sure, but she could look great if she would quit trying to compensate by letting her boobs make up for the rest of her body. She’s still a gorgeous woman, but behind all that makeup it’s hard to tell.

The NY Daily News was scathing in its assessment of Simpson’s scary Vegas-looking outfit at the Costume Institute Gala last weekend. They called her look “oven-based” and said she had “thick gravy-colored spray tan.” Her outfit was “modeled after a Thanksgiving turkey trussed up to be roasted in aluminum foil,” says author Jane Ridley, who compared her to a street hooker with a “porn-star pout.”

It’s not much of a stretch to imagine sisterly rivalry between Jessica and her now more-successful younger sister, Ashlee. Jessica was once the hotter one but now there’s no contest.

Star has Jess jealous of her sister’s good looks and better career, and mentions a supposed instance where her boyfriend John Mayer pointed out a picture of Ashlee, thought it was Jessica and asked her when it was taken:

The trouble began, says another insider, when Jessica’… boyfriend, John Mayer, 29, pointed to a glamorous magazine photo and asked Jess, “How old is this picture of you?” But - whoops! - it was a shot of Ashlee! “Jessica read John the riot act,” says our source, “He definitely touched a nerve.”

Her sensitivity on the subject seems to be the direct result of Ashlee’s emergence as a sex kitten, a role once owned by Jessica. That Ashlee became the hot blonde - a transformation that came courtesy of a surgeon’s knife, a bottle of peroxide and dramatic weight loss - is troubling to Jessica, who has morphed into a buxom and sometimes frumpy brunette due to a dye job and about 20 extra pounds. “Jessica hears the catty talk about how Ashlee looks like her - from two years ago,” says the source. “It totally bothers her.”

What makes it even more painful for Jessica, sources say, is that Ashlee’s career is on the rise, while her own appears to be stagnating. “Ashlee outdoes Jessica four-to-one in CD sales,” says an insider. “And she’s starting to get offered roles that Jessica would give her eyeteeth for.”

[From Star Magazine print edition, May 21, 2007]

It sounds like someone is jumping to conclusions based on what’s known about Jessica and Ashlee, and it could be true since they haven’t been seen out together lately from what I can tell.

They’re also said to not get along with each other’s boyfriends, with Ashlee mad at John Mayer for putting down the celebrity scene that Ashlee loves and Jessica thinking Pete Wentz is a weirdo because he wears makeup. John Mayer is also said to dislike Wentz and think he’s an attention whore.

If only these two would talk smack about each other in an interview, then we might have a real sister fight to talk about. For now, it’s all conjecture.

Here’s Jessica performing at the UNESCO gala in Cologne, Germany on Saturday, where she also hosted the event. She must have gotten the memo, because she looks a lot better.

Thanks to WENN for these photos.