(NaturalNews) Men who are obese have lower quality sperm than men of healthy weights, according to a study conducted by researchers from the University of Aberdeen, Scotland, and presented at the meeting of the European Society for Human Reproduction and Embryology in Barcelona.
Researchers examined the semen of more than 2,000 men who were having trouble conceiving, comparing semen volume, sperm concentration, sperm activity and proportions of abnormal sperm with the men's body mass index (BMI).
BMI, a measure of weight in relation to height, is a commonly used marker of obesity.
Men with a healthy BMI, in the 20 to 25 range, had higher semen volume and lower proportions of abnormal sperm than men who were overweight or obese. This correlation remained significant even after researchers adjusted for other fertility risk factors, including age, alcohol use and smoking.
No effect of obesity was found on sperm activity or concentration.
"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," said lead researcher Ghiyath Shayeb. "This is in addition to the benefit of a healthy BMI for their general well being."
Prior studies have found that obese women are less likely to become pregnant.
Researchers believe that obesity may damage sperm by overheating the testicles or producing abnormal hormone levels. Is also possible that some other lifestyle factor, also linked to obesity, is the true cause of the observed effect.
Shayeb advises that everyone achieve a healthy BMI, whether they plan to conceive or not.
"Adopting a healthy lifestyle, a balanced diet, and regular exercise will, in the vast majority of cases, lead to a normal BMI," he said. "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 body weight."