Berlin, Germany. Major reductions in weight and waist size were an added benefit of long-term testosterone replacement therapy for most male patients, says a new study.

The results were presented today (23 June) at the 94th Annual Meeting of The Endocrine Society (Endo 2012).


Testosterone replacement is the standard treatment for most men with symptomatic testosterone deficiency, according to The Endocrine Society guidelines. However, the substantial weight loss found in the new study — an average of 36 pounds — was a surprise, said the study's lead author, Farid Saad, PhD, of Bayer Schering Pharma in Berlin. Although prior studies using testosterone therapy in testosterone-deficient men consistently show changes in body composition, such as increased lean mass and decreased fat mass, the net effect on weight seemed unchanged in those studies.

Research Summary

The participants were 255 testosterone-deficient (hypogonadal) men with an average age of nearly 61 (range, 38 to 83 years).

Treatment lasted for up to five years. Injections were given at day 1, after 6 weeks and then every 12 weeks after that.

Patients did not follow a controlled diet or standard exercise program but received advice to improve their lifestyle habits.

The treatments restored testosterone to normal levels in the participants.The study by Saad and colleagues had a longer follow-up by at least two years and used testosterone undecanoate, a slow-release, injectable form of the male hormone that is not yet available in the United States. However, it is marketed in Europe, Latin America, Australia and parts of Asia and Africa.

• On average, the men weighed 236 pounds before beginning testosterone treatment and 200 pounds after treatment (106.2 versus 90 kilograms).
  
  
• Weight loss was reportedly continuous, with an average reduction in body weight ranging from about 4 percent after one year of treatment to more than 13 percent after five years.
  
  
• Men lost an average of nearly 3.5 inches (8.8 centimeters) around their waist.

"These results are encouraging because studies show that weight loss drugs and lifestyle interventions have been largely unsuccessful, especially long term," Saad said.

Testosterone deficiency becomes more common with age and many middle-aged men with testosterone deficiency are obese. This has led medical personnel to descibe a vicious circle in obesity and low testosterone. "Obesity is associated with reduced testosterone, and low testosterone induces weight gain," said Saad.