March 4, 2009 -- Men who lose weight after gastric bypass surgery can expect
improvements not only in their overall health, but also in their sex lives, a
new study shows.
Weight loss was associated with increases in the male sex hormone
testosterone and declines in the estrogen hormone estradiol in the study, which
included 64 severely obese men in their late 40s; some had bariatric weight
loss surgery and some did not.
Severe obesity has been linked to lower sperm counts and infertility in men,
but the new research is among the first to show that it is also biologically
linked to an unsatisfying sex life, says study researcher Ahmad Hammoud,
MD, of the University of Utah.
On average, the men in the study weighed around 333 pounds at the start of
the study and had a body mass index (BMI) of 46. Anyone with a BMI of 30 or
more is considered obese.
Over the next two years, the men who had the weight loss surgery lost an
average of 40 pounds and as much as 100 pounds, Hammoud noted.
The researchers measured total and free reproductive hormone levels at study
entry and two years later. Study participants also completed questionnaires
designed to assess their quality of life, including their sex lives, during the
two time periods.
Weight loss and declining BMIs in men who had the surgery were directly
linked to increases in total and free testosterone levels, declines in
estradiol levels, and improvements in self-reported sexual quality of life
Hammoud says the findings offer important new insights into the impact of
obesity and weight loss on sex drive and satisfaction.
"We know that weight loss, no matter how it is achieved, improves overall
health," he says. "Now we see a direct relationship between weight loss,
testosterone levels, and sexual performance."
Obese Men May Benefit from Treatment
The finding may also have implications for severely obese men who lose
weight, he says. "If we treat these men with testosterone, it might improve
their sex drive."
Hammoud says it is not clear if the findings apply to women, because sex
drive in women is less strongly linked to hormones.
"We have shown that sexual satisfaction in women is better after bypass
surgery, but we can't say if this is due to improvements in hormones or
something else," he says.
Weight loss and bariatric surgery expert George Bray, MD, tells WebMD that
he is not surprised that the men in the study experienced increases in
testosterone as they lost weight.
His own research suggests that testosterone levels drop precipitously in men
with BMIs of 40 and higher.
Bray is chief of the Clinical Obesity Center at Louisiana State University
and a spokesman for the Endocrine Society.
"You would expect testosterone levels to be low in this group prior to
weight loss, just as you would expect improvements following weight loss," he