Basiclly on a starvation diet and her mother does not believe me.?

My neighbor girl always comes over. She helped me get my sons nursery ready, she always comes over to play with my baby or even let me take a nap. She is 14 and the sweetest little thing. She always tells me about her high school drama and we have built a relationship. She knows she can come to me with anything. Today she tells me that she is basically on a starvation diet (when i noticed her baggy hoodie and huge droopy eyes with big rings under) she said she has not eaten in 8 days except for soup broth when she almost ped out.After she left I told her mom what she had just confided in me and her mom absolutely would not hear of it and had that " not my daughter defense" WHAT am I to do?!