This was the great discovery from a British Physician, Dr. ATW Simeons:

The first report on the use of hCG for the management of obesity was published in 1954 by the late Dr. ATW Simeons, a British Physician practicing at the Ospedale Salvatori Mundii in Rome.

Working in India, he noticed that the so-called “fat boys,” who showed Adiposogenital dystrophy improved their undescended testis when they were treated with hCG. But he also observed that body fat distribution modified during the treatment course. Therefore he hypothesized that if those children were concomitantly submitted to a very Hypocaloric diet they could reduce their body weight, consuming the “fat on the move”.

Later on, he extended his investigations to patients showing different degrees of obesity, and concluded that hCG might be useful for the treatment of obesity because (424-425). Patients tolerated a Very Low Calorie Diet without suffering headaches irritability, weakness, so common to this approach for weight reduction. Maintenance period after treatment was more effective when compared with simple dietetic procedures. Weight reductions were more satisfactory than those obtained with Standard Hypocaloric Diets Patients lost more body fat (measured in centimeters) from those regions where adipose tissue accumulations were more conspicuous.

He hypothesized that hCG acted at diencephalic level, modulating hypothalamic regulatory Centers, which were in turn responsible for the excessive fat accumulation as seen in obesity.