The HCG diet plan was initially introduced by the British physician, Albert Simeons, as a potential solution for weight loss. This diet plan is comprised of two primary components, namely an ultra-low-calorie diet consisting of approximately 500 calories per day, and injections of the HCG hormone. The fundamental principle of this diet plan is to achieve significant weight loss in a relatively short duration by combining the HCG (Human Chorionic Gonadotropin) hormone with an extremely low-calorie intake.

HCG is a protein-based hormone that is present in high concentrations during early pregnancy. It plays an essential role in maintaining the production of critical hormones such as progesterone and estrogen in pregnant women. These hormones are imperative for the development of the embryo and fetus.