Criminally Insane (1975)

After her doctors declare her ready to return to society, Ethel leaves the psychiatric hospital and goes to live with her grandmother. She soon develops a few odd habits, in particular an insatiable compulsion to eat massive amounts of food. When Grandma locks up the food supply out of fear for her granddaughter's health, Ethel kills her for the keys to the pantry. Left to her own devices, she now indulges her hunger non-stop, murdering anyone who dares to stand in her way. Will anyone be able to stop her?

Criminally Insane is a comedy movie featuring Priscilla Alden.

Criminally Insane is currently streaming for free (ad-supported) on Plex and Plex Player and it's also available on Amazon Prime Video and Cultpix.

It is also possible to buy Criminally Insane on Amazon Video.