Does Lindsay Lohan's Sister Ali Have an Eating Disorder?

Ali Lohan has re-ignited fears that she may be suffering from an eating disorder after new pictures show the fashion model looking gaunt and unhealthy.

The 18-year-old first sparked criticisms about her appearance in September when she landed her first front cover feature for international arts publication Fault Magazine, forcing big sister Lindsay to come to her defense via Twitter.

"I love how haters pick on my sister yet every runway model is just as thin! My sister is gorgeous and I'm so proud of her and her career!!" Lindsay tweeted.

Ali, who signed a multi-year modeling contract with NEXT model management, is reportedly 5'8 1/2" and weighs less than 100 pounds, which some critics say is alarming, according to Radar Online.

"She looks terrible and it definitely seems like there is an eating disorder or super serious dieting going on, which she clearly doesn't need," Hamptons Diet creator Dr. Fred Pascatore told Radar, adding that "it is frightening!"

The teen is often spotted eating modest meals consisting of fruits and coffee, which experts have slammed as unhealthy.

"Every time I see pictures of her she seems skinnier and pastier. I'm really suspicious of an eating disorder. You can see an emaciated body type like hers and the body consuming itself," Nutritionist Majid Ali said.

Ali's new appearance has become so shocking for her fans that some have begun suspecting whether she has had plastic surgery. Her mother, Dina Lohan, denied, the rumors.

"Absolutely not. She's 17, I don't really believe in plastic surgery for young girls. Some do, I don't. They actually said she had an eyebrow lift. I don't even know what that is, but no. And then botox? What 17 year old has wrinkles," Dina said on the "Wendy Williams" show before Ali's 18th birthday last year.

"She did grow three and a half inches..She's taller than Lindsay and I. She's a giant," the mom added.