:), why yes, MofD, I am sort of little, and I feel pretty old lately! I need only about 1650 daily calories to maintain weight at my age & height, with moderate exercise. That’s sad, but just a fact. Where I started from, I needed to lose 20 pounds. I will be okay with 16-17 lbs, it’s not like I am trying to get back to my high school weight.
As I mentioned, I am really dieting, like seriously for the first time in years (there have always been starts & stops, lose & gain, then post-50 things took a drastic turn… upwards on the scale, you all know the drill, I suspect). I do not expect to eat like this for the rest of my life (so few calories on the non-fast days) but I am learning entirely new ways of eating, and do hope to incorporate that into the rest of my life, especially on the non-fast days. Once I reach my goal, I will of course allow myself to “cheat” (maybe have a piece of bread, a glass of wine, or, horrors, even a cookie or two once in awhile), but I am hopeful I will then adjust so that I can continue the maintenance.
I started a supervised fitness program 5 weeks ago, it includes a fitness class every weekday morning (including cardio, strength/weights, endurance), weekly weigh-ins, high protein recipes and daily suggestions, and I have to bring my food calendar in every week. (Writing down every morsel is eye-opening). I also hike with my dog almost daily, and the days I am getting a lot more exercise, I am sure I probably do end up on the upper side of my 12-1400 calorie range, maybe a bit more. I know that I do not go over 1700, though. I am not counting too closely those days, the focus is more on the types of food I choose. Lots of protein to fill me up, one healthy starch/day, tons of veggies, but I am discovering more variety and am spending the time to prepare, which I never did before (not much of a cook). It takes a lot more time, but I figured I focused on food before (seems like constantly), so I am doing the same thing now, just in reverse.
I like this fitness program because it is adjusting my exercise level around my own personal aches & ailments (missed almost 2 weeks due a muscle strain in my back, so they have adjusted what I do in class to accommodate that and prevent a reoccurrence).
In addition to the beginnings of an osteoporosis diagnosis, I did have a major event in my life that prompted this determination to take control of my body. And I am tired of not fitting into most of the clothes in my closet. I am calling this “The summer of Nina” 
The reason I am incorporating the 5-2 is that frankly, the amount of food I was eating daily was just too much, even though it is healthy and “allowed” on my plan. I just can’t have that many calories, because, as morrismm said, I still needed to intake fewer calories for MY body type. I feel much better when I have a couple of low calorie days/week in general, and always have.
I need the reset jump start that the 5-2 provides. And, the other fitness thread is just too intimidating. There will be no half-marathons in my future, my knees doth protest too much.
And yes, I am hungry a lot!! But I am also determined.
edit: cross posted with calmom, we sound pretty similar.