i.e. By every or any thing which God appoints for this end, how unlikely soever it may seem to be for nourishment, as appears in the manna; seeing it is not the creature, but only God's command and blessing upon it, that makes it sufficient for the support of life.
Related Commentaries of Deuteronomy 8:3
Deuteronomy 8:3
3 And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD doth man live.