[Asooka]

Calorie restriction is different to starvation (at least as usually used). When I'm actually starving, I do feel strangely energetic. Your body takes time to switch into starvation mode and during that time you do feel lethargic. IIRC it takes about 6-8 hours of not eating to enter starvation mode.

[narag]

When I'm actually starving, I do feel strangely energetic.

You get the same effect without starving, just restricting carbs:

https://en.wikipedia.org/wiki/Ketosis

[phonypc]

This is a very strange way of using the word starvation. You're more closely describing ketosis, but even that tends to take quite a bit longer than 6-8 hours to be significant.