I once experienced not having the appetite at all, for days. I drank water and coffee alternately without really craving for solid food. When I tried to get me something solid to eat, It was just about a bite size and I had to stop. That's when I realized I wasn't eating healthy. I self diagnosed myself and began a special routine.
I kept my coffee number 1 on the list. I have to have it especially in the office. At home, I could just sleep it off and then I don't crave my coffee anymore late in the mornings.
I started eating breakfast. No buts, no ifs. Either I take coffee first or breakfast as long as I have them in the morning.
I reduced my coffee intake for the rest of the day and drank tea with lemon instead. In the absence of tea, I resort to water and lemon. This helped improve my appetite, the only problem is that I can't wait for lunch time to eat full meal (a minor problem I learned to deal with in the end).
I take my snack in the afternoon along with another glass of lemon tea..
I just had one "tiny, big" problem at dinner where I'm so tempted to eat as much as I want. A big NO NO.