My dog wouldn't eat...?

since we have 2 dogs(boy puppy and 1 year old female) and and the pup likes to eat to much we keep the female inside so she can eat without the pup stealing her food but still she wouldn't eat i puted the food in her mouth and she just putted it out then i gave her some bread and she did eat that but she would eat the human food and not her own.she runs and plays like a normal dog but shes just to to skiny