This is a random topic that really interests me for some reason, so here's some stuff! This page is currently a WIP.

The now-extinct Ajivika school of philosophy was formed in the Indian subcontinent in the 5th century.

Its followers lived extremely ascetic lifestyles, including fasting and eating waste products so as to

minimize harm to any living being. Read more here and here.

Catharism was a Christian dualist movement in the 12th-14th centuries and featured a type of ritual

suicide [this label is debateable] referred to as the endura, undertaken by fasting. This was believed to purify the soul after

a believer had recieved the consolamentum rite which sought to remove sin from the material body.

Read more here, here, and here on pg 22-43