Butter is high in calories, fat, saturated fat, and cholesterol. As it is almost never eaten by itself, but rather spread onto foods or mixed into foods (such as cake or cookies, which may also be high in fat or calories) with almost no consequence on the total mass or volume of the food, the total number of calories and fats is greatly increased. This often leads to people consuming far more calories than intended. I think this is common sense. Anything in excess is unhealthy.
