subsist on

subsist on (something)

1. To manage to survive on something as the sole or primary source of food. The unique creature has evolved to subsist on tiny organism carried by the stream into its ever-open mouth. When I was in college, I was so broke that I subsisted on nothing but rice, beans, and ramen noodles.
2. To eke out a living on something or some amount of money. I just can't subsist on the amount of money you're paying me, so I'll have to start looking for other work. I think you should go back to work, John, because the family can't subsist on my job alone anymore.
See also: on, subsist
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

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
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

subsist on

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, subsist
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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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.