Whence the habit of praying before meals?

One of the patterns of Christians, and I’m told many other religions as well, is the usually-perfunctory prayer that precedes eating a meal. Even the three most common names for the practice (in my experience anyway) speak to a disunity of purpose: “‍bless the food,‍” “‍say grace,‍” “‍return thanks.‍” Is this practice one of gratitude, one of invocation, or a rite we “‍say‍”?

As I try to tease out the scriptural basis of this practice I find little to suggest it either way. It is true that Christ blessed food and/or drink during his ministry several times: to feed 5000, 4000, and the Nephite host, to change water into wine, and to introduce the Eucharist. There’s also a lot of blessing food in the old testament—most sacrifices were blessed meals. But in each instance these references appear distinct from daily meal.

Some more promissing passages are also more oblique. The Lord told the Israelites that if they “‍serve the Lord they God […] he shall bless thy bread, and thy water; and I will take away sickness from the midst of thee,‍” from which we might easily image a habit growing of asking for that blessing before eating. Paul gives advice which may be interpreted as saying a significant portion of the food of pagans was consecrated to idols prior to eating, and can be read as saying that we ought to consecrate instead to God. Nephi instructs we pray God consecrate every action before we act; a communal realization of this for communal meals is easy to imagine.

I do not, in general, have much confidence that God will adjust my eating to my benefit at my requesting it, excepting in a few cases where I am cognizant of the need for His aid. I am grateful for food, but a sincere expression of my gratitude at the time of an average meal will rarely focus on the meal itself; much else moves me much more (see, e.g., 1, 2, 3, 4). Although I respect those who have told me to pray over food, I have sufficiently strong and frequent moments of rebellion that respect has not always kept me at it.

And yet, I pray before I eat. Not out of obedience, or gratitude, or an expectation of divine intervention, but because pausing before nourishing my physical body to check the health of my spirit is a useful checkpoint in my day, a habit that keeps me from straying too far from the eternally important. But even as I avail myself of this tool, I wonder if I might not be missing some more compelling reason.

Praying ere we eat is what we Christians do, but why?