No, ithoughti is not correct. The fact that your body prefers to use processed sugars for energy is completely, 100% natural, and necessary. Glucose provides energy for brain cells, nerve cells, and production of red blood cells. This is stuff that fat cannot normally do. To compensate when a person is in ketosis, body proteins are torn apart, and turned into the glucose necessary to keep your brain functioning -- yep, your body eats itself. That's part of the reason low-carb diets require such a huge protein intake. Body fat cannot break down completely without carbs being present.

After a long enough period of time of glucose deprivation, the brain and nerves develop the ability to get about 2/3 their energy from ketone bodies (made from fat with no carbs present). But that, in itself, is insufficient to sustain life.

The low carb diet without protein offers large weight loss, but that's largely due to lost muscle tissue, water loss, and minerals. As soon as you add protein to the diet, it helps spare the muscle tissue, but the body uses that to get the glucose it needs, just like regular carbs (though it goes through a different breakdown process). As a result, you might as well just eat a low-calorie, balanced meal.

*IANAN (I am not a nutrionist), but I did take a nutrition course in university, and still have my really cool textbook.