Sudden loss of appetite?

aki4567

Last July, I went to the doctor and he told me to do the "zone diet". After I started it, my appetite increased dramatically but it did not seem practical to continue it for various reasons, so I would just eat when I was hungry. My weight did not change during this time.

However, in the past few days, I have barely been able to eat a meal a day. I feel extremely full before I even eat half of what I used to eat. It's 5 PM and all I have been able to eat today is a banana, a cookie, a small ice cream bar and some cheese. This is about the amount I would eat if I had jet lag (which I currently don't) and last time I did, I lost 5 pounds in 2 weeks, which I have gained back since then.

What should I do to gain my appetite back and why might it have decreased so suddenly?

(If it matters, a few years ago I had "eating days" and "non-eating days". Some days I would not eat at all because I wasn't hungry, and on others I could probably empty the fridge.)