Angie Marotto had never needed to be on a diet, but when the scale reached 140 pounds, the 5-foot-tall Marotto decided it was time to act.

She began to exercise more, taking a Pilates class for four months, four times a week.

I did not lose “one single pound after even going four times a week,” she said.

It was then that two friends recommended the hCG diet.

“The truth is that I don’t know how it works, but you do lose weight,” says Marotto, 51, who lost 15 pounds during the month she used a solution of homeopathic drops — bought at a vitamin store — containing human chorionic gonadotropin, better known as hCG, combined with a 500-calorie-a-day diet.

“I did not pass out even once, but I did avoid exercising during the diet,” says Marotto, who admits it was impossible for her to eat only 500 calories a day. “I ate a little bit more because, really, those are too few calories.”

Manuel Jiménez, 28, also lost 23 pounds in the four weeks that he received daily injections of 125 units of hCG. He strictly followed the instructions of not eating more than 540 calories per day given by the doctor who administered the injections. “It’s incredible, the pounds disappear from Day 1. The diet is tough, I felt bad a couple of times, but you hold up when you start seeing results,” he says.

Jiménez and Marotto are among millions of people in the United States who, lured by promises of fast weight loss, have subjected themselves to the hCG diet, ignoring the criticism from the medical community and the Food and Drug Administration, which on Dec. 7 banned the sale of seven homeopathic products with hCG after considering them “potentially dangerous even when taken in the prescribed way.”

The hCG hormone is extracted from the urine of pregnant women who secrete it in large quantities to promote the development of the fetus. It’s composed of 244 amino acids and is generally used in fertility treatments to induce ovulation in women and to treat low levels of testosterone in men.

The use of hCG in treating obesity problems was proposed for the first time in 1954 by British endocrinologist Albert T. W. Simeons. Based on studies of pregnant women in India who followed low-calorie diets and of adolescents in Rome with Frohlich’s syndrome, which affects the pituitary gland and causes abnormal weight gain in the limbs, the researcher concluded that in both cases the patients lost fat instead of muscle due to the hormone’s effect on the hypothalamus, the region of the brain that regulates the appetite.

After experimenting with variations of hCG levels and changes in the patient’s diet, the specialist proposed a new treatment of obesity in his book, Pounds and Inches, which includes daily injections of 125 units of the hormone and a diet low on carbohydrates and high in protein of 500 calories a day. After his death, the weight loss plan fell out of favor because most patients regained the lost weight and also because other researchers have not been able to replicate the results of the studies conducted by Simeons.

In 1976, the Federal Trade Commission ordered the clinics that promoted the use of hCG to include a warning to consumers that “there is no substantial evidence” that the use of the hormone offers weight-loss benefits. More recently, studies published in 2007 by the American Journal of Clinical Nutrition dismissed the usefulness of the hormone, indicating that the weight loss in patients was due to the rigor of the 500-calories-a-day diet and not to the supposed effects of the substance.

However, the hCG diet made a comeback in 2007 when Kevin Trudeau, a well-known author of self-help and nutrition books, included it in the The Cure of Weight Loss They Don’t Want You to Know About. Trudeau’s popularity has launched a new wave of consumers who ask their doctors to administer the injections or ask about homeopathic substances with supposed levels of the hormone sold at vitamin stores and online.

“A healthy diet incorporates all the food groups and combines the gradual loss of weight with exercise,” said Lillian Craggs-Dino, specialized dietitian at Cleveland Clinic Florida. “This regime is not based in proven principles and, besides, hCG is a diet extremely low in calories and we cannot promote this type of diet because it is impossible for the human body to obtain all the nutrients it needs with so little intake,” she says.

“In the long run, this diet can be harmful for your health,” she cautioned.

Her opinion is seconded by many in the medical profession.

“This diet is quite controversial because it does not offer a scientific base and has even been rejected by the Journal of the American Medical Association, one of the most traditional publications in the profession,” says Dr. Juan J. Remos, director of Miami Institute’s Wellness Center and Regenerative Medicine.

“I do not publicize this regime and don’t believe much in it, but if the patient believes, it will work for him because he is going to take the plan seriously and will surely lose weight,” says Remos, who administers the diet only to those of his patients who ask for it and in very regulated conditions, including monitoring potassium, magnesium, calcium and zinc levels.

“We make sure the patient is well supplied and is not left without nutrients. In case of any deficiencies, we then administer them through an IV,” he says.

Remos is also careful in deciding how long a patient can follow this diet. He also warns patients that “they will always regain the weight unless certain precautions are taken. The only way to stay in the ideal weight is through a dramatic increase in the energy expense, in other words by exercising.”

Marotto has regained three of the 15 pounds she lost during the diet, but said the experience helped her.

“I have gotten used to eating less and to counting the calories.”

Jiménez admits that he regained the 23 pounds he had lost “plus two or three more.” His goal for 2012 was to lose weight again, but this time in a different way: “I don’t want the same thing to happen again; it’s very frustrating. This time I want a healthy option,” he says.