Why does your stomach call before lunch?

You eat lunch at the same time. Soon, your body learns this time. Before lunch, you may feel hungry. Your stomach may even make sounds. Your body gets ready for food. (pubmed.ncbi.nlm.nih.gov)

For example, Mia eats lunch after class. One day, her class ends late. But Mia feels hungry as usual. Her body expects lunch now.

So, your stomach has no little clock. Your whole body learns your daily pattern. Meal times can become body habits. Sometimes, hunger is also a memory.