Kelly Osbourne Friends Concerned Over Weight Loss, But Understand She's Grieving

Kelly Osbourne's lost a lot of weight recently, and while it has some folks around her concerned ... it sounds like it's a direct linked to her famous father's death.

Sources with direct knowledge tell TMZ … Kelly's circle believes much of her concerning weight loss is tied to grief over her late father, Ozzy Osbourne.

We're told friends are concerned, but they know she's grieving and they know she's working on it ... and they're giving her grace when it comes to her dramatic weight loss because they know it's all tied to the grieving process.

Our sources say Kelly is aware of how she looks, but it's difficult for her to focus on her appearance while dealing with the tragedy of losing her father ... and keeping her body at a healthy weight is hard when she's grieving and not eating.

It's been a little over 7 months since Ozzy passed ... and it's clearly been hard on Kelly.