Testosterone Linked to Weight Loss in Obese Men
When Levels Were Low, Testosterone Replacement Led to Lost Weight, Smaller Waists
May 9, 2012 -- Testosterone replacement may promote weight loss in obese older men who have low levels of the male sex hormone, a new study shows.
But before men try to lose weight by bumping up their testosterone, experts agree that more studies are needed to show that the treatment is both safe and effective.
Researchers followed a group of mostly older, overweight men receiving injections of the hormone for up to five years to treat erectile dysfunction and other symptoms associated with low testosterone.
Their findings were presented at the 19th European Congress on Obesity in Lyon, France.
The men who were treated the longest lost more than 30 pounds on average over the course of the study, and also showed improvements in blood pressure, blood glucose, and LDL (bad) cholesterol.
Researcher Farid Saad, DVM, says the dramatic weight loss came as a surprise.
"This study was not performed for the purpose of promoting weight loss," he tells WebMD. "This was an incidental finding that was entirely unexpected."
Low Testosterone Common in Obese Men
The study included middle-aged and older overweight or obese men with low testosterone levels being treated with testosterone replacement at a single urology clinic.
A total of 214 men remained in the study for at least two years, and just over half of these men were followed for another three years or more.
All the study participants received a long-acting injected testosterone, with two injections given during the first six weeks of treatment followed by injections every three months as long as they remained in the study.
Men who were treated the longest lost the most weight and saw the biggest reductions in waist circumference and body mass index (BMI).
After five years of follow-up, the average weight loss was 35 pounds and the average waist circumference dropped from about 42 to 38 inches. Most men also saw improvements in triglyceride levels, blood pressure, blood sugar, and LDL cholesterol.
Saad is a researcher with Bayer Pharma AG, of Berlin, Germany. Bayer manufacturers the long-acting testosterone treatment the men received, which has not been approved for use in the U.S.
Saad says the men in the study may have lost weight on the testosterone therapy because they had more energy to exercise.
"This is a theory, and, certainly, more research is needed to confirm our findings," he tells WebMD.