I also consume about 1700 calories a day, but for my frame, that is only about 25% restricted (significant, but nowhere near ozmonster's).
Though since starting CR a year and a half ago I have not experienced the "boundless energy" of some other cronies, I have not experienced a dip either. My energy overall has probably increased a little bit, but not dramatically.
As far as sleep is concerned, it also has been affected very little.
This is my explanation.
You have to get your body to begin the first stage of starvation, before every meal.
The only way to do this is to:
1) shave off most of the fat from your body so there is little reserve. do this slowly over a long period of time if you are overweight or you will burn muscle and body tissue (something we want to avoid at all cost) along with the fat.
2) once you have around 3% or 4% body fat, use CR calculator to figure on 40% reduction.
3) adhere to CR regimen religiously with a macronutrient ratio of 40%c-30%p-30%f.
4) NEVER go more than 5 hours without eating.
For a more detailed list of my routine, see
http://www.imminst.o...showtopic=26056.
So the process goes like this.
Body begins to starve but never gets there. At this point my armchair theory is that some evolutionary biological mechanism is triggered and your body produces hormones that "give you wings."
that's been my experience anyway.