I agree about hunger coming in waves; I'd go 12 hours without even thinking about food, then it's all I could think about for an hour. Probably didn't help that I was still cooking for the family!
For those interested, most of the benefits (for me) happened after the 5th day. Thats when the hunger and caffeine withdrawal ended.
I don't know all of the science behind it, but I can honestly say that I never felt better/healthier in my life.
There is a lot of evidence to suggest that fasting, and even intermittent fasting, is a good thing (actually, I seem to recall some papers/articles have ended up on HN). Fasting has also been shown to regenerate the immune system[1]
Besides, I have enough body fat to supply calories for a good bit longer than 5 days :)
[1] https://news.usc.edu/63669/fasting-triggers-stem-cell-regene...