Hand to mouth is a phrase which is used to denote living with the help of bare essentials. Living from hand to mouth means having absolutely meagre resources. What the phrase actually means is that, as soon as the resources are coming in, they are getting spent on basic necessities. To live from hand to mouth is to have a precarious existence. It literally means to intake or eat whatever one can lay their hands on. For example, "he was living hand to mouth after he was fired from his workplace".
