Though subsequent hCG diets have tinkered with the elements, most programs hold pretty true to the original formed by Dr. Simeons.
Each round of treatment lasts a minimum of 26 days, and 23 of those days require a daily dose of hCG, either through injections or under-the-tongue drops. Treatment may last as long as 43 days (with 40 injections), unless a patient loses 34 to 40 pounds (15 to 18 kilograms) before the allotted time has passed. Patients don't receive hCG injections for the last three days of any treatment period so the hormone can cycle completely out of their bodies before they resume a normal diet. (It also takes about three days for hCG's effects to "kick in.")
Why stop after 40 days? Simeons noted that subjects seemed to develop immunity to hCG after 40 days and required a six-week break from the diet to fully resensitize to it. Simeons recommended no more than four total treatments, separated by breaks.
In addition to receiving the hormone, dieters are instructed to cut their daily intake of calories to just 500 a day, but not until after the third dose. Once the hCG is active in a dieter's body, its release of long-stored fat provides the body with the calories it needs to burn to get through a day (a day, it should be noted, without much exercise). As long as fat deposits are being released for use, the 500 daily calories being ingested is supposed to be enough to sustain the dieter without the crazy hunger pangs one would normally experience on a 500-calorie diet. Once a dieter drops the excess weight, the treatment must stop, because hCG only affects stored fat. Once that's used up, the body will quickly reject a self-imposed limit of 500 total daily calories.
Of the little food you can eat on the hCG diet, it's supposed to be high in protein and low in starches, carbohydrates and high-fat foods. Dairy, sugar and alcohol are forbidden, and if you goof up, you should spend the next 24 hours drinking water and eating six apples [source: Haupt].
Can this diet possibly be a healthy way to lose weight? Read on to find out some of the dangers of the hCG diet.