The HCG Diet for Weight Loss: Miracle or Mirage?

The human chorionic gonadotropin (HCG) diet is another example of a "fad diet" that has regrettably become a money-making machine for many homeopathic clinics and alternative healthcare practices. Self-professed health gurus and quack physicians continue to assert that HCG boosts metabolism and reduces appetite, but empirical evidence to support these claims remains nonexistent [2]. A meta-analysis from 1995 found that only one of the 12 available studies on the HCG diet produced favorable weight-loss outcomes [1].

Things become even more egregious when you consider that the HCG "supplements" that accompany this diet are unlikely to contain any HCG (hormone) and may do more harm than good. Not to mention, HCG is poorly absorbed orally and must be administered parenterally for proper efficacy.

But if people that follow the HCG diet lose weight, doesn't that mean HCG is the reason?

Well, not quite. Here's why the HCG diet "works" for rapid weight loss and why HCG itself has nothing to do with it.

What Is HCG?

Human chorionic gonadotropin (HCG) is a peptide hormone synthesized in the female placenta during early pregnancy. (Intuitively, men do not produce HCG.) The biological purpose of HCG is to signal to the mother's body that pregnancy has begun, initiating an increase in progesterone from the corpus luteum in the ovaries.

HCG is an analog of luteinizing hormone, a pituitary peptide hormone that stimulates ovulation and spermatogenesis in women and men, respectively. As such, HCG hormone injections may be used medically to enhance/restore fertility in both men and women [3].

What Is the HCG Diet?

Like most fad diets, the HCG diet is a very-low-calorie diet that promises dramatic weight loss (e.g. 20 to 40 pounds) in a matter of weeks. The severe calorie restriction prescribed by the HCG diet limits followers to a trifling 500 calories per day. For reference, that's equal to eating roughly 4 to 5 tablespoons of peanut butter a day.

Even for sedentary individuals, 500 calories is a nominal daily calorie intake. Sure, an ultra-low-calorie diet will promote weight loss, but not in a healthy, sustainable fashion. Quite the contrary, eating so few calories during a weight-loss phase will make the process insufferable for just about anyone. It may also lead to abnormal eating patterns and body image issues.

The alleged benefit of HCG weight-loss products is that they strongly suppress appetite and increase metabolic rate. In theory, a person can lose weight quickly if they can consume just a few hundred calories per day without the consequences of rampant hunger and reduced metabolic rate. Alas, there's no evidence, let alone a proposed mechanism, for how HCG makes that possible [4].

The United States Food and Drug Administration (FDA) issued a statement in 2020 urging consumers to avoid taking HCG diet products as they are likely to be unsafe or, at best, ineffective for weight loss. HCG hormone injections are, however, FDA approved for treating female infertility (and male infertility, in special instances).

Why a Very Low-Calorie Diet "Works" for Weight Loss

The HCG diet helps people lose weight by virtue of it being a very-low-calorie diet; the bunk HCG products that go along with the diet play no role as a weight-loss aid.

Bear in mind that very-low-calorie diets "work" for rapid weight loss, but that doesn't mean they're optimal or sustainable. If anything, people who follow the HCG diet and lose weight are likely to regain the weight once they return to regular eating habits.

Notably, extreme calorie restriction for weeks/months poses an imminent risk to lean body mass and vital, energy-demanding organs like the heart and brain. Active individuals will also struggle to keep up with their weight-loss exercise regimen when calorie intake is so low.

HCG Weight-Loss Products vs. HCG Injections

Since HCG is a peptide hormone, like human growth hormone, it must be injected or supplied parenterally to preserve its functional structure. Orally ingesting HCG leads to rapid enzymatic degradation of the peptide and a loss of its function before it reaches the bloodstream. Therefore, homeopathic HCG products are essentially snake oil.

But HCG injections serve a purpose, just not one related to weight loss. HCG is a prescription medication used to treat infertility, primarily in women. Occasionally, HCG is prescribed as an ancillary for men on testosterone replacement therapy (TRT) or as a standalone treatment for low testosterone [5]. HCG may also classify as a performance-enhancing drug by increasing testosterone production in males.

Once a male begins using exogenous testosterone, their hypothalamic-pituitary-gonadal (HPG) axis will reduce the production of luteinizing hormone. Consequently, there's a decline in endogenous testosterone production as exogenous testosterone "takes over," so to speak. The suppression of the HPG axis is why a male's testicles will shrink in size after extended use of testosterone or other androgenic steroids.

A reduction in sperm counts is also a common side effect of steroid/testosterone use, leading to fertility issues down the line. Hence, HCG injections help restore fertility and testicle size in men who have a history of steroid use.

Don't Follow the HCG Diet to Lose Weight

Losing weight is a matter of quality, not (just) quantity: The goal should be to burn body fat and hold on to your muscle mass. Very-low-calorie diets like the HCG diet are generally not ideal for meeting that goal.

HCG weight-loss products pushed by advocates of the diet are pseudoscientific garbage. Do not waste your money on them.

And remember, highly restrictive weight-loss diets often lead to poor long-term outcomes due to the weight regain. Think of caloric restriction like a slingshot: the more you "pull back" on calorie intake, the greater the urge to "let go" and overeat.