Disdain is the feeling that someone is beneath contempt, unworthy of notice. Arrogance is a sense of superiority, being better than others. These two often go together. As a person who follows a lchf diet I may have superior knowledge and the ability to act on that knowledge, but instead of feeling disdain for people who eat high carb diets, especially ones filled with sugar and processed junk foods, I try to cultivate compassion for people who either do not know better or are unable to act on their knowledge for any of a variety of reasons. Truthfully, this is sometimes hard to do but neither arrogance or disdain have any chance of leading me towards beneficial actions whereas if I react with compassion there is some chance that I can be of benefit.