When you’re hungry, the hydrochloric acid in your empty stomach can slosh about and hit the lower oesophageal sphincter (the valve that holds the top of your stomach closed). This is also what happens when you throw up, and it triggers similar feelings of nausea.
Hunger can also stimulate the ‘area postrema’ structure in your brainstem, which detects bacterial toxins in the blood to make you throw up in response to food poisoning. For some reason, very low blood sugar can sometimes trigger a false alarm.
Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.