Lindsay Lohan's family has begged her to put on weight.

The 'Mean Girls' actress' mother Dina and 15-year-old sister Ali want the thin star to return to the family home in Long Island, New York, so they can make sure she is eating.

A source said: "That way Dina and Ali can look after her and stop her skipping meals. It would be the best thing for her.

"We know it's stress behind the weight loss."

But the 22-year-old star - who has reportedly lost nearly 14lbs from her already-slender frame in the past two months - has reportedly refused to leave Los Angeles without her girlfriend, DJ Samantha Ronson.

The source said: "She won't be away from Sam. She's too insecure."

Lindsay hasn't even been tempted by junk food bought for her by her worried sister.

The source explained: "For a while, Ali was buying her pizza, fries, chips and all her favourites. But she just sits there, taking a few bites, then picking at the rest. She really isn't fooling anyone."

Lindsay's father Michael Lohan also recently revealed he is worried about his daughter's weight.

He said: "Lindsay goes through her fluctuations in weight for different roles. I'll talk to her about it - I'll see what's going on."

Michael expressed his concerns on social networking website Twitter.

In the first of a series of posts seemingly aimed at Lindsay, he wrote: "Eat. please."

Lindsay's weight plummeted in 2005, but she soon regained a few pounds after admitting she was "sick and scared".