According to the BBC
, in a study, hormone-deficient men were given testosterone supplements in a similar way to HRT for older women.
The study looked at 115 testosterone-deficient men aged between 38-83 years with a mean age of 61. They were injected with the hormone every 12 weeks to increase levels. Men lost an average of 16kg (35 pounds) over five years when testosterone levels were increased back to normal.
The mean waist circumference fell from 107 centimeters (42 inches) to 98 cm (38.5 inches).
"Raising serum testosterone to normal reduced body weight, waist circumference and blood pressure, and improved metabolic profiles," said Dr. Farid Saad, lead author of the study.
But it might not be the testosterone itself.
"We came across this by accident. These men were being given testosterone for a hormone deficiency - they had a range of problems - erectile dysfunction, fatigue and lack of energy.
"When we analyzed the data we found that every year, for five years, they had lost weight. It may be that the increased testosterone restored their energy levels and led to a behavioral change of being more physically active," Saad said.
Approached for comment, Sanjay Kinra, researcher at London School of Hygiene and Tropical Medicine, agreed and urged caution.
"It is quite possible that a drug that is improving the mood of middle-aged people over a period of time will likely make them a bit more active and help them lose a little bit of weight, but it is a serious drug, testosterone, and it causes serious health effects," he told AFP
Testosterone, a steroid hormone secreted by the male testes and to a lesser extent by the female ovaries that affects brain development and sexual behavior, has been linked by some researchers to prostate cancer and heart disease.
Another expert, Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City, added that "anecdotally we have been seeing improvement in elderly men with low testosterone taking testosterone, including improved cholesterol, more lean body mass and fat loss."
Mezitis agreed that the weight loss may have been a result of feeling better and stronger, allowing the men to exercise more, HealthDay
But there's another reason why men in the study may have lost weight.
Dr. Bradley Anawalt, a spokesman for The Endocrine Society and chief of medicine at the University of Washington Medical Center in Seattle, who was not involved in the study, noted the study was paid for by German pharmaceutical giant Bayer Pharma –– which makes testosterone supplements.
"If you were a drug company, the best product in the world would be a drug that causes you to lose weight, increases muscle and strength and improves your sex drive," he told HealthDay News.
The study was presented at a medical meeting in Lyon, France. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.