I usually just tell people that I'm a health nut and they get it. Although I eat more carbohydrate than most on this board (loads of fruit, maple syrup, raw honey, coconut sugar, white rice, etc.), I still follow the basic tenet of preferring real food over processed junk.
Many people simply don't understand the connection between what they eat and how they feel, which is why they lash out at others who eat healthily. They tend to perceive health food as a trendy luxury that has nothing to do with energy levels, skin quality, mood, etc.