With the national obesity rate reaching alarming heights, it seems new fad diets come and go - some with better results than others. One such diet is the HCG diet which combines an extremely restrictive diet (500 calories a day) and a small amount of the hormone HCG (Human Chorionic Gonadotropin). Many patients who have undergone this diet will swear by it but some are more skeptical: how does the HCG diet work exactly?

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As seen on The Dr. Oz Show, HCG is a hormone that is secreted by pregnant women to ensure their fetus gets all the nutrients it needs to develop properly. As a weight loss strategy however, according to Dallas HCG provider Dr. Kevin Light, "The theory is that HCG 'tricks' the body into thinking it is pregnant. Evolutionarily, propagation of the species trumps individual survival and thus sacred fat stores will 'open up' if needed to ensure that the fetus will get adequate nourishment, even at the expense of the parental host."
In the 1950s, Dr. ATW Simeons found that small doses of the natural hormone HCG, commonly found in high amounts in pregnant women, could decrease appetites and shave down inches on his overweight patients (both male and female).
Flash forward to the present, one of the main concerns about HCG is since the inception of the diet, the market has been flooded with supplements that claim they include the appetite-suppressing HCG when in reality, many of these products have low to no trace of the hormone. The only way to get an effective dosage strength for weight loss is to have it prescribed by a medical doctor. Generally speaking, this form of HCG is administered through daily shots of the hormone. "With proper medical supervision, the diet is entirely safe," says Dr. Light, "However, patients with certain heart and kidney conditions should probably avoid this type of diet."
Many physicians who specialize in medical weight loss are working with individuals who are trying to lose a lot of weight in a short period of time. Many of these patients find that the HCG diet has worked well. However, although the hormone has been in use for the past 50 years, there is no medial research that proves HCG prevents hunger. FDA approved as a fertility drug, HCG does not have clearance as a weight loss drug.
The diet is broken down into four phases.
- Phase 1: Loading Phase
During the first 3 days of the diet, patients eat high in fat food while starting the HCG to open up the fat metabolism pathways. After which, HCG is taken daily with a strict diet of 500 calories of mainly protein and vegetables, no carbs or dairy.
- Phase 2: Final Days Of HCG
The last 4 weeks of HCG dosing in which patients continue to administer the daily HCG and follow the strict 500 calories per day diet.
- Phase 3: Transition
During the 3 week transition phase, HCG is discontinued and calorie consumption is slowly increased to a target number based on the patient's basal metabolic rate ? generally between 1300 and 1800 calories a day for most people.
- Phase 4: Maintenance
In the final maintenance phase, a low carbohydrate diet is introduced and followed indefinitely with the new metabolic reset. The diet can be repeated multiple times, with a 6 week window between sessions, until the desired weight is obtained.
Dr. Light says HGC works by telling the part of the brain which controls fat metabolism and storage to start burning fat instead of protein when calories are slashed as they are in this diet. Therefore, the restrictive diet of 500 calories a day sustains the individual because the body is using up fat stores as energy while the HCG also represses the feeling of hunger. "The net effect is a weight loss that can range from half a pound to two pounds per day. Patients routinely lose 25 - 30 pounds with this program," states Dr. Light, "This effect is seen in both men and women. It's important to stress that HCG causes absolutely no changes in men such as growing breasts or other feminizing characteristics. It functions only to change the way your body handles excess fat."
Some in the medical community fear that due it's dramatic steps and results, the diet is too severe and in the long run, unsustainable to keep the weight off. But many patients have said the diet not only helps them lose weight quickly, it teaches them portion control because the amount of food you're allowed to consume is so small. Dr. Light believes, "By resetting the hypothalamus to a new low carbohydrate default point which minimizes carb cravings, an ongoing low carbohydrate diet is achievable after this diet."