Butter is in fact one of the foods which are allowed on the Atkins diet. It is low in carbohydrates which is ideal for many people who are trying to lose weight. Those who are on a diet will need to avoid certain fattening foods such as butter because they are filled with all of the bad kinds of fats.
The Atkins diet is big on encouraging people to cut down on fat as much as possible with the food they eat, so you will need to follow that mantra as much as possible. This includes avoiding foods like butter that are extremely high in saturated fat.