I recently started taking a medication whose side-effects, among others, include loss of appetite. Until I experienced that I don't think I really understood the difference between appetite and hunger. The first two days on the medication I, following the instructions of my psychiatrist, made sure to take it in the morning with a meal. On those two days I don't think I ate anything after that until the medication wore off 12 hours later. When it did wear off, it hit me hard. I felt very ill and didn't know if I needed to eat something or throw up.
Fortunately I realized why this was happening and resolved to make sure I ate throughout the day while taking this medication. This was surprisingly harder than I anticipated. I noticed that I felt hungry—that is, I felt the need to eat—but I had no desire to eat. When I thought about a specific food none of them seemed appealing and most seemed downright unappetizing (even my go-to "vice" foods). Now that I was no longer confounding appetite and hunger, I was aware of what my body was actually telling me regarding its food needs and how often I had used my appetite as an excuse to go above and beyond its requests.
As I've thought more about this phenomenon, I see a notable parallel when it comes to my depression. Depression, for me, is like having a hunger for life and its joys and experiences but not having the appetite. This is probably the best way I can describe the duality at the core of my illness wherein I simultaneously experience both desire and either apathy or even repulsion towards the same thing.
One tidbit of cliché advice I've frequently received is something along the lines of, "If you don't enjoy what you're doing maybe you're not on the right path." I understand the sentiment. If you're not going to enjoy a career as an actuary you probably shouldn't study actuarial science. But this is advice based on hunger, not on appetite. Because I've had so much experience with little to no appetite for life or anything, I've doubted every decision I've made. I've had to learn (and am still learning) to find the decisions for which I hunger and how to feed that hunger, even when I have no appetite.
Most of the time I wonder why I don't have the appetite I want to have. Appetite is connected to desire so if I want it enough it feels like I should be able to change it. But I can't. Or I don't know how. I wish I could get rid of my depression and gain that appetite. I'm not sure if that will happen so for now I'm trying to figure out how to live and experience life without the appetite to do it.