"...and you could say it was more like a glider out of control when fasting, with lots of up and down draughts. A powered descent (eating) is smoother and quicker."
haha ;). Well fasting gives us that variable of "ton of temporary water loss"... making it look sporadic because we always gain all or most of that back. i always keep 2 weight logs, one for scale weight and another for "estimated actual weight". At the end of my recent 10 day fast (ended 3/4/09) i was 199.5 on the scale, but i believed myself to "actually be" 212.5, having started at 219.5. 34 days of healthful eating and exercising later, the two have merged at 200.5.
Since i like your analogy so much, i now have a green landing strip of my own... 180 lbs by June 20 that i might feel "20 years old" again. :p.