Bitter orange (citrus aurantium) is a nervous system stimulator included in many weight loss and energy boosting supplements. A review of literature by scientists from Creighton University Medical Center concluded that bitter orange extract by itself or with other stimulants such as caffeine and synephrine increases energy levels and promotes weight loss. They also concluded that the supplements are safe when taken as directed. They do not increase heart rate or blood pressure or alter common blood or urine tests. Energy boosting supplements reduce the perception of fatigue during exercise. They make workouts seem easier and might boost performance by increasing training adherence. These products make athletes want to train and help sustain workout intensity. (Internal journal of Medical Sciences, 9: 527-538, 2012)