The diet's popularity is on the rise again with renewed chatter on the Internet and TV shows, but critics warn it's a fraud and could be risky.
Still, users can't ignore the success stories.
Nina Chantele is a popular radio personality on Chicago's WGCI and KISS FM. Grace LaJoy Little is a business executive. David DeCarlo is a hair stylist undergoing chiropractic care for a sports injury. What do they have in common? All have been doing a version of the HCG diet.
"Twenty eight pounds in 30 days," said Chantele.
"I've lost a total of 20 pounds," said DeCarlo.
"I've lost about eight pounds," Little.
HCG or human chorionic gonadotropin is a pregnancy hormone that is commonly used as an infertility treatment. So what does it have to do with dieting?
Daily doses of HCG are coupled with a 500 calorie a day diet. Claims are HCG decreases appetite, resets metabolism and forces the body to use stored fat as energy.
Decarlo and Chantele have been doing the diet through an online company called Body Reset. Chantele is even talking about it on the air. She says she lost 50 pounds in almost one year.
"You definitely need the HCG to do a 500 calorie a day diet. There is no way that you can eat 500 calories without that supplement and be okay," said Chantele.
HCG can be taken in a variety of forms but it's not approved for weight loss. Many in the medical community insist it's nothing more than snake oil.
So why are so many people claiming to lose weight? Critics say anyone can slim down on a measly 500 calories a day.
"If a person is taking drop by mouth, the likelihood that the active substance is getting in the blood stream is too low. So essentially those people are being scammed out of their money," said Dr. Rasa Kazlauskaite, endocrinologist, Rush University Medical Center.
Other concerns: lack of solid scientific proof and there are worries about long term use.
"Hormones can have side effects if not appropriately used," said Dr. Kazlauskaite.
The FDA recently took issue with the homeopathic version of HCG sold on the Internet. A spokesperson questioned the effectiveness and called it "econocmic fraud" saying they "are not recognized by the FCA as homeopathic drugs, so they are unapproved drugs and are illegal."
"I don't know why they are claiming things they have no regulation under," Gary Arbuckle, chiropractor and co-owner BodyReset.
Arbuckle says, despite all the critics, HCG works.
"I've seen it work too often in almost every single person who does it to discount it as placebo or something else. There has to be something to this. Exactly what it is, research will find that out," said Arbuckle.
Grace LaJoy Little says she's working with a holistic practitioner. She's been on the diet about two weeks and feels good. What does she think about the drops?
"I don't know if it's making the difference. I don't know. I'm just doing it," said Little.
The cost for HCG products ranges from $15 a bottle to hundreds of dollars for injections.
Another concern is whether this diet sets people up for the yo-yo effect where they lose weight only to gain it back.
All of the practitioners ABC7 talked with stressed the importance of consulting a health professional before starting any kind of diet.