Obese of the world, be on the look out. You could be failing
on more counts than one. Fertility, to wit. Your sperm might be of poor
quality, researchers say.
Too much fat around their testicles perhaps causes them to
heat up and rendering them infertile in the process.
University of Aberdeen researchers in the UK looked at
the sperm of over 2,000 men in couples having problems conceiving.
The heaviest men had a higher proportion of abnormal sperm,
as well as other problems.
The scientists told a European fertility conference losing
weight probably boosted fertility.
Being obese is already known to affect women's chances of
The men were divided into four groups, according to their
BMI (body mass index).
Other factors which could affect fertility, such as smoking,
high alcohol use and age, were taken into account by the researchers.
Men who had a healthy BMI of 20 to 25 were had higher levels
of normal sperm than those who were heavier.
They also had higher semen volume, the European Society for
Human Reproduction and Embryology meeting in Barcelona was told.
But those with a higher BMI had lower volumes of seminal
fluid, and a higher proportion of abnormal sperm.
There was no significant difference between the four groups
in sperm concentration or activity.
Other studies have also linked obesity to DNA damage in the
Dr Ghiyath Shayeb, who led the research, said: "Our
findings were quite independent of any other factors and seem to suggest that
men who are trying for a baby with their partners, should first try to achieve
an ideal body weight.
"This is in addition to the benefit of a healthy BMI
for their general well being.
"Adopting a healthy lifestyle, a balanced diet, and
regular exercise will, in the vast majority of cases, lead to a normal BMI.
"We are pleased to be able to add improved semen
quality to the long list of benefits that we know are the result of an optimal
The researchers will now look at male BMI in fertile and
infertile couples to see if the poorer semen quality is directly linked to poor
fertility, and examine further how obesity can damage sperm.
Dr Shayeb said there were a number of possible explanations,
including different hormone levels in obese men, overheating of the testicles
caused by excessive fat in the area, or simply the lifestyle and diet that
leads to obesity also causing poorer semen quality.
Dr Ian Campbell, chair of the charity Weight Concern, said
it was known that overweight people had a tendency to have fewer children, BBC reports.
He said there had been a suspicion that was mainly due to
lack of opportunity.
"But if weight actually has a detrimental effect on
sperm quality, that's really interesting," he said
"It's one more reason for men to lose weight."