subsist on

subsist on something

to exist on something; to stay alive on something. We can barely subsist on this amount of money. We need more! They are able to do no more than subsist on what Mrs. Harris is paid.
See also: on

subsist on

v.
To survive by using something as a source of food: The people of the war-torn region subsisted on bread, water, and cheese for several months.
See also: on
References in classic literature ?
A more forlorn set they had never encountered: they had not a morsel of meat or fish; nor anything to subsist on, excepting roots, wild rosebuds, the barks of certain plants, and other vegetable production; neither had they any weapon for hunting or defence, excepting an old spear: yet the poor fellows made no murmur nor complaint; but seemed accustomed to their hard fare.