I have a question about the mechanics of digesting food. Would that be on topic here? I'm thinking no, am I right?
Not unless there's some subtle or tenuous connection to the cooking process that I'm not anticipating.
We do seem to have a biology site on the network now; if your question is at a reasonably technical research-ish level then you could try asking there, although I suspect, like most of the other science sites, that it'd get closed if it's deemed overly simplistic or if you're looking for somebody to break a complex subject down into layman's terms.
I believe you are correct, that would be a medical question.