No appetite?

I often find myself feeling hungry but have no appetite, or having a lot of appetite but not being hungry.

But the last few days have been different. I've had very little to no hunger and zero appetite. That's why my first and usually last meal over the last few days has only been in the afternoon.

Today, however, I had to go away. I didn't want to buy anything in town, so I forced myself to at least have a peach for breakfast. Since then, I've only had a cup of juice and water. So I haven't eaten anything except for one peach all day, and I still have zero appetite.

Is this just a phase that's passing? Or does it mean something and I need to treat it somehow?