Ephedra has a stimulant effect on the nervous system. So it may cause you a significant change of your heart functions (increased pulse and blood pressure) but also a lot of other changes.
While it might suppress or reduce appetite for a while ephedra will cause severe problems for patients with an eating disorder. The perception of hunger and satisfaction is very often one of the major problems of patients with an eating disorder. Ephedra manipulates the awareness of normal body signals and may cause severe disturbances and a major negative influence on the course of your eating problem.