In one of my high school classes there was a concept we discussed called the “nausea of indecision”, a phrase taken from James Joyce’s Eveline, whereby a literary figure is brought to a crucial point in the plot characterized by intense adversity. Usually at some point in the struggle there is a difficult decision to be made, and as a matter of the course of literature the character’s inability to decide is apparent. This indecision should be so acute that it would cause us normals in the real world to vomit if we were in their place.
Naturally, this applied more to classical or romantic literature than the modern, but there is still exists a remnant of this idea. Good books, we’re told, bring the protagonist to their extreme breaking point and reveal, say, where their true loyalties reside or whether they can truly overcome their fatal character flaw. While I think that’s decent advice, it can get out of hand and transform your story into a melodrama set in a gamed, Candide-like fantasy world that would infuriate the laws of probability. While a certain degree of this is appropriate for certain genres, like suspense, you don’t want to alienate readers by introducing surrealism into a realistic setting.
Anyone who has done high-intensity strength training or cardiovascular exercise (or watched “The Biggest Loser”), knows that nausea comes when exercise becomes overwhelming. It’s a little traumatizing but it’s ends up a blessing, because it means that you’re “breaking through plateaus” in your fitness. Nausea in general is a horrible experience — especially those few agonizing seconds before the big heave — but it means, both literally and literature-ly, that the damaging cruft is being removed and transformation is taking place.
As a neat reading practice in the novel you’re currently reading, watch out for the point at which it would make the most sense that he or she (or they?) would forcibly revisit their lunch. It might not make too much sense in that scene that they would blasts chunks, but the most likely scene is probably the most crucial in the story.