You have probably heard of the HCG diet, a plan touted for its seemingly magic weight loss results. If you or someone you know has benefitted from this diet, you can thank Dr. Simeons, who discovered the effectiveness of human chorionic gonadotropin, or HCG, as a weight loss tool.

His work was conducted in the 1950s. One of his major interests as a physician was studying obesity. He carried out a multitude of tests and found that patients injected with HCG, a hormone produced naturally in the human body, could eat less without feeling hungry or irritable, two major unwanted side effects of most low calorie diets. Patients loss large amounts of weight without changing their exercise habits or much of their daily routine.

Today, the good doctor’s diet has been adapted into many different variations. Some such adaptations recommend different forms of HCG, such as pills or drops rather than injections, while others have made changes to his diet plan. However, one thing remains the same; his important discoveries about HCG remain central to all of these weight loss solutions.