HCG stands for human chorionic gonadotropin. It's a hormone produced by pregnant women. The HCG diet is a diet created by a british endocrinologist named Albert Simeons. Through experimentation he came to believe that low doses of HCG would cause the body to loose irregular fat during periods of low calorie eat. The diet consists of taking a shot of HCG once a day and eating 500 calories from a very strict food regimen. 100g of meet, 1 vegetable, 1 fruit and for some one bread stick (which I am not eating).