What is the ruling on abstaining from food for a limited or unlimited period, especially in prison, if it is the only means for the prisoner to demand his human rights?

Abstaining from food as a form of protest is forbidden (haram (definition)) if it leads to harm or destruction, in accordance with the Almighty's saying: "And do not throw yourselves with your own hands into destruction" (2:195) and "And do not kill yourselves" (4:29). And according to the Prophet's (peace be upon him) saying: "There should be no harm nor reciprocating harm." However, if it does not cause harm and is for a permissible purpose, such as repelling injustice, then there is no objection to it.