feed off (of) (someone or something)
1. Literally, to use someone or something as a source of sustenance. The kittens still need to feed off of their mother for a few more days.
2. By extension, to use something to one's advantage. These insurance companies are just trying to make money by feeding off our anxieties.
feed off (of) something
to eat something in particular customarily. (Of is usually retained before pronouns.) This creature feeds off fallen fruit. Mosquitoes seem to want to feed off of me!
feed off
v. To be nourished, sustained, or fueled by something: The microbes feed off the decaying seaweed. The politicians are feeding off of the public's fear.