The HCG diet has been popular for many years.
It's an extreme diet, claimed to cause fast weight loss of up to 1-2 pounds per day.
What's more, you're not supposed to feel hungry in the process.
This article takes an objective look at the science behind the HCG diet.
HCG, or human chorionic gonadotropin, is a hormone present at high levels in early pregnancy.
In fact, this hormone is used as a marker in home pregnancy tests (1).
HCG has also been used to treat fertility issues in both men and women (2).
However, elevated blood levels of HCG may also be a symptom of several types of cancer, including placental, ovarian and testicular cancer (3).
A British doctor named Albert Simeons first proposed HCG as a weight loss tool in 1954.
His diet consisted of two main components:
- An ultra low-calorie diet of around 500 calories per day.
- The HCG hormone administered via injections.
Today, HCG products are sold in various forms, including oral drops, pellets and sprays. They are also available through countless websites and some retail stores.
Bottom Line: HCG is a hormone produced in early pregnancy. The HCG diet uses a combination of HCG and starvation-level calorie intake to achieve dramatic weight loss.
HCG is a protein-based hormone produced during pregnancy.
What HCG basically does is telling a woman's body that it's pregnant.
HCG helps maintain the production of important hormones like progesterone and estrogen, which are essential for the development of the embryo and fetus (4).
After the first three months of pregnancy, blood levels of HCG decrease.
Bottom Line: HCG is a hormone that is produced in large amounts in the first three months of pregnancy. It stimulates the production of essential pregnancy hormones.
Proponents of the HCG diet claim that it boosts metabolism and helps you lose large amounts of fat, all without feeling hungry.
Various theories attempt to explain the mechanism behind HCG and weight loss.
These studies compared the effects of HCG injections with placebo injections when given to individuals on a calorie-restricted diet.
Weight loss was found to be identical or nearly identical between the two groups.
Furthermore, they found that the HCG hormone did not significantly reduce hunger.
Bottom Line: Several studies have found that weight loss on the HCG diet is due to drastic calorie restriction. It has nothing to do with HCG, which is also ineffective in reducing hunger.
One common side effect of weight loss is decreased muscle mass (9).
This is especially common on diets that severely restrict caloric intake, such as the HCG diet.
The body may also think it's starving and reduce the amount of calories it burns in order to conserve energy (10).
However, proponents of the HCG diet claim that it facilitates weight loss resulting from fat loss only, not muscle loss.
They claim that HCG also elevates other hormones, boosts metabolism and leads to a growth-promoting (anabolic) state.
If you're on a low-calorie diet, there are much better ways to prevent muscle loss and metabolic slowdown than taking HCG.
Bottom Line: Some people claim that the HCG diet helps prevent muscle loss and metabolic slowdown when severely restricting calories. However, there are currently no studies to support this.
The HCG diet is a very low-fat, very low-calorie diet.
It is generally divided into three phases:
- Loading phase: Start taking HCG and eat plenty of high-fat, high-calorie foods for 2 days.
- Weight loss phase: Continue taking HCG and eat only 500 calories per day for 3 to 6 weeks.
- Maintenance phase: Stop taking HCG. Gradually increase food intake but avoid sugar and starch for 3 weeks.
For people who have less weight to lose, 3 weeks is recommended for the weight loss phase. Those who need to lose a lot of weight may be advised to follow the diet for 6 weeks and even repeat the cycle (all phases) several times.
As for the weight loss phase, you're only allowed to eat two meals per day, usually lunch and dinner.
HCG meal plans generally suggest that each meal should contain one portion of lean protein, a vegetable, a piece of bread and a fruit.
You may also get a list of "approved" foods to select from in specific amounts.Butter, oils and sugar should be avoided, but you're encouraged to drink lots of water. Mineral water, coffee and tea are allowed as well.
Bottom Line: The HCG diet is usually divided into three phases. During the weight loss phase, you take HCG while eating only 500 calories per day.
Most of the HCG products on the market today are actually "homeopathic."
What this really means, is that there is literally no HCG in them.
Real HCG, in the form of injections, is approved as a fertility drug. It is only available through a doctor's prescription.
Only these injections are able to raise blood levels of the hormone, not these "homeopathic" products sold online.
Bottom Line: Most of the HCG products available online are "homeopathic," meaning they don't actually contain any real HCG.
HCG has not been approved as a weight loss drug by agencies like the FDA.
On the contrary, they have questioned the safety of HCG products, as the ingredients are unregulated and unknown.
There are also a number of side effects associated with the HCG diet, such as:
These may be largely due to the starvation-level calorie intake, which is pretty much guaranteed to make a lot of people feel miserable.
Additionally, in one case a 64-year-old woman was on the HCG diet when blood clots developed in her leg and lungs. It was concluded that the clots were likely caused by the diet (15).
Bottom Line: The safety of HCG products has been questioned by official agencies like the FDA, and numerous side effects have been reported.
The HCG diet limits caloric intake to around 500 calories per day for weeks at a time, making it an extremely weight loss diet.
Any diet that is this low in calories will make you lose weight.
However, numerous studies have found that the HCG hormone has no effect on weight loss, and doesn't reduce your appetite.
If you're serious about losing weight and keeping it off, then there are plenty of effective methods that are much more sensible than the HCG diet.
For more science-based tips on weight loss, check out this article: 30 Easy Ways to Lose Weight Naturally (Backed by Science).