What Are the Side Effects of the HCG Diet?

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The HCG Diet is an extremely low-calorie diet combined with injections of an illegal supplement called HCG. HCG stands for human chorionic gonadotropin and is a pregnancy hormone produced by the placenta. The HCG Diet is unrelated to pregnancy.

As with any extreme diet that significantly restricts food groups or calories, the HCG Diet is not recommended as a healthy measure for weight loss. In fact, evidence shows that HCG injections do not lead to additional weight loss beyond what can be produced by the calorie restriction alone. This diet also can cause several side effects that you should be aware of if you are considering it.

The HCG Diet limits calories to 500 calories per day. This is highly ill-advised unless being closely monitored by a medical professional. The HCG supplements do not cause additional weight loss and are considered a dangerous scam by the Food and Drug Administration.

HCG Diet Side Effects

If you are considering the HCG Diet, you need to realize that it is not a safe eating plan. Likewise, it is often accompanied by some very dangerous side effects that could put your health at risk. Here is an overview of the potentially harmful side effects of the HCG Diet.

Rapid Weight Loss

Although the rapid weight loss caused by extreme calorie restriction is part of why people try the HCG Diet, weight loss that occurs too quickly has more negatives than positives. Fast and excessive weight loss is seldom sustainable. Any weight lost is highly likely to be regained.

In fact, weight-loss diets are notoriously unsustainable. In a meta-analysis that reviewed the results of 29 long-term weight loss studies, over half of study participants’ who lost weight regained it within two years, and 80% of the lost weight was regained by 5 years. The extreme restriction of the HCG Diet would make it even more unsustainable.

Central Nervous System Symptoms

Several symptoms connected to HCG use are related to the central nervous system, according to researchers. These include symptoms like headache, irritability, restlessness, and fatigue. People have even reported experiencing depression and aggressive behavior.


Very low-calorie diets typically cause hunger—sometimes extreme hunger. Eating far below your total daily energy expenditure causes hormonal changes in leptin, ghrelin, insulin, and peptide YY (PYY), among others. These hormones are responsible for feelings of hunger and fullness. 

The frequency and size of your meals can alter levels of these hormones, leading to hunger. Your body is doing its best to warn you of low-calorie intake in an effort to prevent the harmful effects of too little nutrition.


Very low-calorie diets like the HCG Diet put you at an increased risk of developing gallstones, both asymptomatic and symptomatic. The risk of developing symptomatic gallstones that require hospitalization or cholecystectomy is multiplied by three compared to a more moderate reduced-calorie diet. Researchers believe the cause may be a lack of dietary fats.

Poor Sleep

Those on the HCG Diet may experience poor sleep quality and quantity. In fact, research shows that waking up during the night (nocturia) and trouble falling asleep (insomnia) are frequently reported while on the HCG Diet.


There are reports of water retention, known as edema, when on the HCG Diet. Another type of swelling that can occur in males is gynecomastia, which is an enlargement or swelling of the breast tissue.

Irregular Heart Beat

Protein loss from the heart muscle can occur on the HCG Diet. This loss as well as mineral deficiencies due to a lack of nutrition can lead to an irregular heartbeat. Irritation of the heart leading to heartbeat irregularities (ventricular tachycardia), is dangerous. Speak to a healthcare provider right away if you experience this symptom.

Other Side Effects

Aside from side effects particular to the HCG diet, there are other known common side effects that may result from very-low-calorie diets. These include:

  • Weakness and tiredness
  • Nausea and vomiting
  • Constipation
  • Dehydration
  • Low blood sugar
  • Bad breath
  • Diarrhea
  • Dizziness
  • Hair loss
  • Muscle loss

Ending the HCG Diet

Ending the HCG Diet will very likely lead to weight re-gain. Highly restrictive diets are unsustainable and almost always result in the lost weight being regained.

This can happen gradually or rapidly, depending on how much you change your diet. Because the HCG Diet is extremely low-calorie, the chances of rapid regain are high.


The HCG Diet is not safe or recommended for anyone. It is especially vital to avoid this diet if you are taking medication, especially for diabetes, as a diet deficient in calories will also reduce carbohydrates and affect insulin.

Pregnant and breastfeeding women should not take HCG or go on a very low-calorie diet. And, children and the elderly could be significantly harmed by the HCG Diet. Mineral imbalances and insufficiencies can lead to severe consequences for anyone, especially young and older individuals.

There is even some evidence that the HCG Diet can increase your risk of cancers. More research is needed. But, if you have a personal or family history of cancer, it is even more imperative to avoid the HCG Diet.

A Word From Verywell

There are no circumstances in which the HCG Diet is recommended. It is a dangerous and unhealthy approach to weight loss that can result in serious side effects. Moreover, there is no proof of the diet’s efficacy beyond the weight loss caused by restricting calories. The HCG supplements are unnecessary and risky. 

A balanced nutritional plan that creates a slight calorie deficit and focuses on nutritionally rich foods is best. Weight loss is not always the correct choice for everyone, and health is about more than just your weight. If you are interested in learning more about weight management, talk to a health care provider or a registered dietitian. If you are currently on the HCG Diet, let your provider know immediately.

12 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rachel MacPherson, BA, CPT
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.