Here you go -- Daily Apple blog post on the subject of being fat-adapted:
Why Fat, Not Carbs, Are the Preferred Fuel for the Human Body | Mark's Daily Apple
Notice he says:
You might notice any or all of those effects -- for example, less energy and mood swings, and fewer problems with hunger and cravings.It increases insulin sensitivity, modulates energy and mood swings, and allows for a normal and healthy drop in hunger and cravings. There is a downside, however: you can’t train long and hard day-in and day-out in the fat paradigm.
You might sleep better, too. And you certainly shouldn't have to wake up to eat.
If you were to buy a cheap portable glucose meter, you'd probably see your blood-sugar level was generally lower throughout the day.
And, of course, you should notice excess fat on your body reducing. If you have excess fat on your body ... well, that's stored energy. However, if you're used to eating excessive quantities of carbohydrate you can't access that energy. This is because your fat-burning enzymes get down-regulated, because you keep over-using a different pathway for your energetic purposes
It's like money locked in a safety-deposit box to which you've lost the key.
(Why the dietary "establishment" doesn't understand this I can't imagine. But they don't.)
Anyway, once you're fat-burning you are able to access that fat and burn it. So if your pants are getting looser, that's a sign, too.