I think maybe I wasn't clear. Normally when you eat, you expect to not feel hungry any more. In particular, if you are targeting a calorie deficit or weight loss you look forward to that "joy of food" sensation, a big part of which is the glucose that absorbs almost instantly and raises your blood sugar, and more of which absorbs over time beginning immediately. If you are on a low carb meal you will miss that feeling entirely. You won't feel from fat (though you will if you have plenty of protein and fibe) and you won't have the blood pressure spike that most of us associate with "food good" (note I don't mean the extreme spike you would get from eating pure sugar necessarily, just any higher than baseline peaking).

So the psychological programming is getting used to not expecting that spike (and possibly that 'full' feeling), and still feeling you sated your self.