At the top of the list of odd diet fads, the hCG diet has been widely discredited by scientists, but remains popular because of its weight-loss promise. The diet requires that you eat only 500 calories a day and get daily injections of the hormone human chorionic gonadotropin (hCG.) Also available in pill form, hCG is the hormone produced by the placenta during pregnancy.
In 1954, British physician A.T.W. Simeons theorized that hCG is what allows mothers-to-be to access fat reserves to feed their fetuses. He published a book, Pounds and Inches: A New Approach to Obesity, in which he suggested that hCG could help people access their fat reserves and achieve weight loss.
The hCG Diet: Pros
The promised benefits of this diet fad include:
  • Rapid weight loss. Some people who have followed the hCG diet find that it results in rapid weight loss with minimal hunger. Keri Gans, RD, a New York-based dietitian and spokesperson for the American Dietetic Association, says people on the hCG diet will lose weight simply because they are consuming so few calories.
  • Fat reduction. Advocates also claim it reduces fat, not muscle.
Related: The Fad Diet Factsheet
The hCG Diet: Cons
Nutritionists and the American Society of Bariatric Physicians warn against the diet because of:
  • Little medical support. “It is not at all healthy for you,” Gans says. It would be impossible, she continues, to find “an accredited physician or registered dietitian — the two professionals you should be going to if you need help with weight loss — who would endorse the hCG diet.”
  • Expensive injections. The daily injections or hCG pills, Gans says, could get quite costly. Most people buy the hormone pills on the Internet or go to clinics that advertise hCG injections.
  • Likely weight regain. People are likely to put back on the weight as soon as they go off the diet, Gans says. In fact, they may continue to eat less and still gain weight because their body, deprived of nutrients, can go into starvation mode and burn fewer calories to survive.
  • Few food choices. Because the hCG diet is so calorie restrictive, there aren’t many exciting hCG diet recipes, Gans says. Your choices usually include different ways of seasoning basic foods like fish, chicken, turkey, or lean beef. Seasonings can add flavor and variety, but no calories. Many of the hCG diet recipes are for single servings.
Related: Is Rapid Weight Loss Safe?
The hCG Diet: Short- and Long-Term Effects
Short-term, Gans says, hCG dieters are going to feel lousy. “You will be low in energy. You will be fatigued. You will be cranky and irritable,” she says. “There’s no way you’re going to be getting enough nutrients and you won’t have energy to exercise, which can help you not only lose weight, but also maintain long-term weight loss.”
People who stay on the hCG diet for a long time could become malnourished. “You can’t meet your nutritional needs on 500 calories a day,” explains Gans. “The U.S. dietary guidelines are based on a 2,000-calorie-a-day diet.”
The hCG diet promises quick weight loss and can work at first because you are eating far fewer calories than you are burning. However, it’s important to remember that healthy weight loss takes time and most often can’t be accomplished through diet fads.
“I always tell my patients that it didn’t take you two weeks to gain those 20 pounds, so don’t expect to lose them in two weeks,” Gans says. “You need to change your behaviors for the long-term, and fad diets don’t do anything about changing behaviors except encouraging some new, not-so-healthy ones.”