Effect of Obesity On Semen Quality

A recent study on British Medical Journal shows an inverse association between body mass index (BMI) and sperm quality: as class of obesity increases, sperm count and sperm motility reduces. The researchers associated it to endocrine deregulation resulting from a complexly altered reproductive hormone profile arising from aromatization of fat which other previous studies also shows.

The researchers said, ‘ the finding of reduced sperm motility with obesity in our study is also in keeping with results from previous studies which showed a negative association between BMI and sperm motility . They also found  association between increasing obesity class and semen parameters. This was similar to the findings from previous studies and weight reduction has been shown to improve sperm quality in obese men . These varying results may be attributed to the population sizes of these studies, Furthermore, the difference in ethnicity/race may also be contributory .




A total number of 84 black African males were used in the study most of whom had infertility problem. 42 of whom were obese (study group) while the rest (control group) had normal BMI (20-25kg/m2). The average BMI of the obese group was 32.9±2.8kg/m2 while for the non-obese was 22.4±1.4kg/m2. There was no statistical significant difference observed in the age and educational status between the two groups, says the author.

Their findings reveal significant effect (a negative correlation) of increasing BMI(body mass index) on testosterone {p=0.000} and on FSH {p=0.008} levels. Low testosterone levels are thought to be the result of; decreased SHBG binding capacity, direct action of leptin and other adipocyte derived hormones on Leydig cell function and impaired functioning of the hypothalamic-pituitary-testicular (HPT) axis , the researchers say .However, the study did not observed any inverse correlation with LH and estrogen levels.

The research clearly shows an inverse but significant relationship between obesity and serum testosterone and FSH amongst the study population. This suggests that male obesity has an adverse effect on the quality of semen amongst male partners of infertile couples, the researchers said. They are however of the opinion that more study of a larger number will warrant further confirmation of their research.




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