Obesity and Male Infertility

A Practical Approach

Ahmad O. Hammoud, M.D., M.P.H.; A. Wayne Meikle, M.D.; Leonardo Oliveira Reis, M.D., MSc, Ph.D.; Mark Gibson, M.D.; C. Matthew Peterson, M.D.; Douglas T. Carrell, Ph.D.

Disclosures

Semin Reprod Med. 2012;30(6):486-495. 

In This Article

Proposed Mechanisms for Infertility in Obese Men

Male Obesity and Semen Parameters

Male obesity is suspected to cause alterations in semen parameters. We and others have demonstrated that male obesity is associated with altered semen parameters ([Fig. 1]). In particular, male obesity has been associated with lower sperm concentration,[19–22] total sperm count,[21,22] total motile sperm count,[22,23] total progressively motile sperm count,[19] sperm morphology, and increased DNA fragmentation.[23]

Figure 1.

Current understanding of the pathophysiological changes related to obesity that can affect the reproductive function in men.

Other studies, however, show conflicting results. A recent meta-analysis concluded that current evidence does not support a relation between increased body weight and reduced semen concentration.[9] The main limitation of this meta-analysis was its restrictive nature. Only 5 of 31 identified studies and only two semen parameters (sperm concentration and total sperm count) were suitable for pooling, and authors have recognized that further researches are necessary. Studies that reported sperm morphology or composite outcomes such as total motile sperm count were excluded due to methodological fragility. However, these composite parameters, total motile and progressive motile sperm count, correlate more accurately with male fertility than crude semen parameters.[24–7]

The recent findings by Håkonsen et al reporting a correlation between baseline BMI and semen parameters in 43 men and the improvement in total sperm count and sperm volume after a weight loss program in subanalyses of <10 patients, presents evidence of causality in the relationship between increased weight and altered semen parameters.[25]

The relation between obesity and sperm parameters is complicated by the various exposures studied such as BMI, weight, percentage body fat, waist circumference, and waist-to-hip circumference and the diverse outcomes explored such as sperm concentration, sperm motility, sperm morphology, total sperm count, total motile sperm count, total progressive motile sperm count, sperm morphology, and semen DNA fragmentation. This multifaceted aspect of the relation can be linked to the multiple mechanisms proposed for the relation between obesity and male infertility. It is possible that in each unique obese infertile man, a different mechanism is in play that would lead to one or more of the alterations in semen parameters and not in others.

Male Obesity and Sexual Function

Erectile dysfunction (ED) has been correlated to fertility in men.[26] In a survey of health professionals, obesity was associated with a 1.3 relative risk for ED.[27] In men reporting symptoms of ED, overweight or obesity is found in 79% of subjects.[28] We also found that in severely obese men, BMI was associated with increased avoidance of sexual encounters and increased difficulty with sexual performance, leading to lower satisfaction with sexual life.[29] Sexual dysfunction in obese men is related to hypogonadism and elevated levels of proinflammatory cytokines.[30] Manifestations of these physiological changes include reduced libido, reduced coital frequency, and ED.[31] The markers of inflammation (tumor necrosis factor [TNF]α and interleukin [IL]-6) are positively associated with ED.[32] Obesity is also associated with cardiovascular risk factors,[33] known to be independently linked to ED.[28]

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