Congratulations on your first set of up and down days. Sounds like they both went well. And what a great compliment to receive about your age. You must be glowing.
I am doing something interesting with tracking my weight that you might be interested in, with your love of stats. I'm making two weight graphs. One is normal, with every day tracked, and my weight zigzagging up and down. I do shade in the down day columns to see where my calorie restriction falls with the numbers.
But the second graph is the one I am really liking. I chart two different lines: a thick line for my morning-after-down-day numbers, and a thin line for my morning-after-up-day numbers. This way, instead of a zig-zag, which can be mentally disheartening, even if you know the general trend is downward, I am seeing two lines, both going down. I like looking at it, I must confess. (They overlap. As the horizontal markings I just use day 1, day 2, day 3, etc of whichever type it is. The Up day line will gradually get a little longer, as I slip a few extras in, here and there.)