What is hCG? 
hCG stands for human Chorionic Gonadotropin. This is a hormone that is naturally found in the pregnant women's urine. Dr. Simeons believed that using hCG with a VLCD (very low calorie diet) and some proper exercise, can cause the body to get rid of body fat without effecting or losing muscle.
There are three kinds of fat. The first fat is called structural fat. This fat is found around your organs and acts as a protectant/cushion. The second type of fat, reserve fat, is located throughout the body and provides energy/fuel. The third type of fat is the abnormal fat found throughout the body. This fat continues to accumulate, is trapped and difficult for the body to reach and use for energy. hCG assists the hypothalmus, which triggers the release of this fat in the system to be used by the body for energy and fuel. The fat is removed from the body and then the fat cells are emptied, broken down and the body releases them so they are no longer there to store fat. Those fat cells are gone and so is the fat that was stored in the cells!
hCG helps to reduce your appetite and helps mobilize fat to be used for energy. hCG actually triggers your body to release 1500 to 2500 calories of your own fat per day to be used as energy. If you add to that another 500 calories you eat on your diet, then the low calorie diet is a little easier then it sounds.
Independent studies have shown hCG actually boosts feelings of well being, evens out mood swings and improves sleep!