In the late 1950s, A.T.W. Simeons developed a diet plan that included the administration of human chorionic gonadotropin, or hCG, also referred to as the pregnancy hormone because it is made by cells that form the placenta. This hormone is produced during pregnancy and attaches itself to the wall of the uterus to nourish the fertilized egg. Simeons’ theory was that this natural hormone would nourish the body while his patients followed a very restricted, 500-calorie per day diet. Of course, his patients lost weight because they were not eating, but because the human body cannot thrive on 500 calories per day, his patients complained of side effects, including muscle weakness and muscle loss, along with extreme fatigue. Although Simeon’s hCG diet earned a negative reputation, the real cause of these side effects was not related to the hCG itself, but rather the dangerously low caloric intake.