the mission of IDEA has changed, or rather grown, over the years. As you can see from the acronym, IDEA, it was originally seen as a professional association for those who taught dance exercise (International Dance Exercise Association) but it grew to represent personal trainers as well, particularly as many who started in the world of dance exercise moved on to offer personal training as well. Covering those who work in mind body was a natural extension, as many people who teach things like yoga work in the same facilities and teach other formats, or do one on one training. I would say a greater number of people who are full time in group fitness and/or personal training would be likely to be members of IDEA than those who are full time in yoga. Not all yoga teachers self reference primarily as fitness instructors, and not all who work full time ever work in fitness clubs. The latest extension has been toward wellness coaching and nutrition. My sense is that IDEA is less likely to be the primary professional home for fully trained and licensed nutritionists, unless they are involved in other areas of fitness, since they have their own professional association. There are however, many fitness people who are involved in various ways in teaching about healthy living and other aspects of nutritional education.