Queasiness at the thought of food

I’ve avoided asking about this in the hope that it’ll go away. I’ve developed a recurring issue in recent months where the mere thought of food makes me queasy. I’m fine with actual eating, but thinking about food in any way makes me feel like I’m going to be sick.

I’m eating because I have to eat, but nothing appeals to me any more. Today’s the first time it’s happened in a few weeks, but I’m not seeing any particular pattern. Any thoughts on what could be causing this?