'No Anorexia' model Isabelle Caro dies aged 28
Isabelle Caro died on 17 November after being treated for an acute respiratory illness, Swiss singer Vincent Bigler told journalists.
He added that he did not know the exact cause of death.
Ms Caro appeared in posters for an anti-anorexia campaign in 2007, but the ads were banned in several countries.
It was not clear why it took so long for her death to be made public.
The anti-anorexia campaign came amid a debate among fashion circles on the use of "ultra-skinny" models on the catwalk.
The AFP news agency reported her as saying at the time: "I thought this could be a chance to use my suffering to get a message across, and finally put an image on what thinness represents and the danger it leads to - which is death."
The model, who was 5ft 4in tall (1.65m) at the time of the poster campaign, reportedly weighed 32kg (five stones).
Ms Caro's acting instructor, Daniele Dubreuil-Prevot, told the Associated Press news agency that Ms Caro had died after returning to France from a job in Tokyo.
She said family and close friends had held a funeral ceremony in Paris last month.
Mr Bigler, who was a friend of Ms Caro, told Swiss media: "She was hospitalised for 15 days with acute respiratory disease and was recently also very tired, but I do not know the cause of her death."