11/30/2006 AT 07:30 AM EST
It's only been a month since Nicole Richie announced she was seeking treatment
for her inability to gain weight, but friends are noticing a difference, PEOPLE reports in its upcoming issue.
"She has (put on) at least 5 lbs.," says a source close to the actress. "She wants to prove she's trying to change."
The newly brunette Richie has even "distanced herself from a lot of (old) friends," adds the source. Among those old friends is Rachel Zoe, 35, Richie's stylist for the past three years, with whom Richie split last week
Richie, who before seeking treatment had dropped to around 90 lbs., hit the American Music Awards last week in a short vintage Christian Dior dress with the help of new style consultant Cristina Ehrlich looking "much healthier," said an onlooker.
Now she's ready to shoot the fifth installment of her reality show The Simple Life,
which was postponed due to her treatment. Says her on-again pal and Simple Life
costar Paris Hilton: "She looks better than she's ever looked. I love it."
So, it would seem, does Richie. "She’s doing great," says a friend who spoke to her over Thanksgiving. "She's taking care of herself and is in a good place."