Suggest Treatment For Weight Loss In A Diabetic Person

My brother is severely under weight and he is loosing his teeth in the process due to bone loss which limits him to what he can eat.. He refuses to go to a hospital , I am afraid he will die if he is not admitted to a hospital
What can my sister do to help him get better? can she legaly sign him in a hospital without his permission to get the care he needs? he has diabetes high blood also..