Demi Moore‘s troubled marriage to Ashton Kutcher is said to be taking its toll on the 48-year-old actress, who stunned onlookers when she showed up (solo) at the New York premiere of “Margin Cell” this past Monday (Oct 17) looking thin and frail.

“Everyone was remarking how thin Demi was, more so than usual,” an observer at the premiere told US Magazine. “She’s very upset, and hasn’t been eating,” another source told the magazine.

An expert estimates that Moore, who stands at 5’5,” appears to weigh a shocking 90 pounds!

Demi was already looking thin before her marriage started falling apart, but now things seem to be getting worse.

“She looks like she has gone even lower in the past month. Those protruding cheeks and rather gaunt face are not a healthy sign,” nutritionist Majid Ali (the expert) explained to RadarOnline.com, adding that, “Stress can really debilitate an appetite.”

“It is clear from the pictures that she looks as if she is going through some rough times,” New York-based psychotherapist Jessica Aronson, who has not treated Demi, told Radar.

“It is not uncommon for people to lose or gain weight during times of stress. Very often women use their weight as a way to control something when other areas of their lives feel out of control,” such as by restricting calories or over-exercising, explained Aronson. “Women focus on their bodies because it distracts them from the pain of the issues in the relationship.”

Despite reports of her husband having unprotected sex with a blond party girl named Sara Leal at the hard Rock in Hotel in San Diego last month, on the very same night of their sixth anniversary (of all nights Ashton, really?), Moore was seen wearing her wedding wing at the premiere Monday.

Ashton also wore his ring last weekend at Bill Clinton’s charity concert, but that doesn’t mean that the couple are still “together.”

A neighbor says Ashton has moved out of the home they once shared together in Los Angeles:

“I don’t think Ashton is living at the house anymore. I haven’t seen him for over two months. I used to see him every once in a while and now I never see him. I saw Demi last week with her daughter Rumer, but as far is Ashton is concerned, I think he’s living at another place.”

Another neighbor added:

“It wasn’t unusual for Demi and Ashton to have get-togethers on the weekend. They would have BBQs and intimate parties, but I don’t think they have had any gatherings for at least three months. It’s sad because they always seemed like such a happy couple!”