The HCG diet or pregnant woman urine diet allows you to lose up to three pounds a day on a 500 calorie diet. It's a very low calorie diet along with HCG administration as injections or oral suspensions.HCG is produced in the placenta of pregnant women. When you are on a HCG diet, it does not strip away your muscles or vitamins from your body, it takes away only the fat. Initially surviving on 500 calories/day would be difficult and can lead to hunger pangs, but within two weeks on the diet, hunger will be sustained and eating a small amount itself will leave you feeling full.