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 ?
I had indeed another bank bill about me of #30, which was the whole of what I brought with me, as well to subsist on in the country, as not knowing what might offer; because this creature, the go-between that had thus betrayed us both, had made me believe strange things of my marrying to my advantage in the country, and I was not willing to be without money, whatever might happen.