The ONLY reason you are not losing weight: You are taking in more calories than you are expending i.e. "in a caloric deficit."

That's it in a headline. Yes, it makes a difference what kind of calories you are taking in if you want to retain or gain muscle mass, not be tired, and/or not get sick. Yes, it makes a difference what kind of training you are doing if you want to lose weight fast or slow and again retain or gain muscle mass while you diet. But in the end, you must be in a caloric deficit to lose weight - and if you are, you will.