Why do I sometimes feel nauseous when I'm really hungry?
I feel you—I get that a lot, too. There are two likely answers. One is that your stomach produces excess acid when you’ve been ignoring your hunger for a while, and that acid can splash up into your esophagus and cause nausea.
The other possibility is that you’re extra sensitive to ghrelin, the hormone our bodies make to alert us to our hunger. For some people, high levels of that hormone can make them slightly nauseous. If your nausea is severe, though, you should definitely talk to your doctor about it—it could be a sign of metabolic syndrome.