(Cover) - EN Showbiz - Ali Lohan's mother Dina is apparently not concerned by her daughter's recent weight loss.

The 17-year-old model caused alarm last week when she was seen looking thinner than she has ever been.

Lindsay Lohan's little sister has recently signed a modelling contract with Next Model Management but her slimmed down figure is not worrying her mother.

RadarOnline are reporting that Lindsay is telling her friends that their mother Dina has not seen any cause for alarm.

"Dina is adamant that Ali is just going through a big growth spurt and there is absolutely no cause for concern," an insider told the site.

"If Dina thought for one moment that Ali was suffering from an eating disorder or feeling the pressure to be thin, she would terminate Ali's modelling contract and get her the necessary help.

"Ali is the one who has pestered her mom for years to get into the business. Dina held off for years, but felt now the time was right for Ali to get into the business. As long as Dina isn't concerned, Lindsay isn't worried either."

Lindsay defended her younger sibling on her Twitter page and disagreed that her sister had lost too much weight.

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

Ali has also denied having plastic surgery after reports she had undergone work on her face. (C) Cover Media