In my experience, people often eat in dreams, but the actual eating most often takes place "off camera" - that is to say, the dreamer is about to eat, and there is a jump cut to having just eaten, but the dream memory of actually putting food/drink into his/her mouth, tasting/chewing, and swallowing is very rare.
When we do actually remember eating in a dream, it's worth asking "Do I actually taste the food, or feel it in my mouth?" It's pretty rare if we do.
Since we eat so often in waking life, it is something of a puzzle why we seldom have or remember "the full eating experience" so in dreams.
One symbolic pattern that I have noted over years working with the few dreams where the dreamer actually remembers eating and tasting, is that in that moment, the dream food or drink crosses the very significant symbolic boundary between "me" and "not-me". In other words when food (which is obviously "not me") is taken into the body it becomes "me."
At one level, it seems to operate as a metaphor of withdrawing projections... (which would certainly account in large measure for its rarity in the dream world!) Projection just means we see qualities in others that we do not yet know are qualities in ourselves. For example, perhaps we see a friend as exceptionally loving and caring. We would not recognize it in our friend if we did not carry the capacity to be that way ourselves. I'm suggesting that the food and drink in the dream are really parts of ourselves but we are still seeing them as "other" until we "take them in." In the course of taking the food and drink in, in the dream world, it becomes an accepted and recognized part of "myself". So the very unusual act of eating and drinking in the dream becomes a symbol for our ability to own projections in our waking life.
At another, related level, it often suggests, in my experience, that the dreamer is growing/changing/evolving as a direct result of accepting ideas, information, spiritual perspectives, etc. from others in waking life. In that sense, the full sensual experience of eating in a dream is often an indication that I have accepted as true, (for me, at very least), some specific teaching, suggestion, or admonition from another person, (book, group, tradition, film/tv, workshop, etc.) in waking life.
In addition, how the food or drink tastes, and how nourishing it appears to be in the dream is often a very reliable symbolic indicator of whether or not the "truth" I have consciously accepted in waking life is actually right for me at deeper levels of my psyche and authentic self.
At this level, I believe this archetypal implication around the full sensual experience of eating is also related to the archetypal implications of vomiting in a dream - which is so often associated with getting rid of introjections (unconsciously accepted ideas or attitudes of others) that I previously believed were actually true about me. This introjection of false self-understanding most often has its roots in these fake truths having been projected onto me at an early age by my parents, (or others to whom I gave authority) - things like "You're not gay!", "You're not an artist!", "You want to be 'X' just like me!", etc.
What about the interesting situation in a dream when I know what kind of food or drink I would really like but I end up taking some dream character's suggestion to eat something else. My experience with working with dreams suggests to me that the dreamer wants some sort of nourishment in waking life, (often spiritual nourishment), and may be settling for something less, or other.