Source please.
I want to learn more about selective targeting of different macros for catabolism.
I'll play ball and answer you with seriousness because I *think* Jockey is sort of conflating a few things.
When someone says "burn fat for energy" I think colloquially they mean adipose tissue, i.e., the fat you want to lose, rather than fatty acids in the diet, but realistically your body is going to use dietary energy before stored energy, all things being equal. Therefore, a statement like "If you are loading up on carbs, then you burn carbs. You want to burn fat instead." is probably at best kind of imprecise.
But who knows, maybe google does have something to say about targeted catabolism.