Male Infertility Fertility Fears – Fate of the Fat Ashok Agarwal,1 Stefan S du Plessis,2 Stephanie Cabler3 and Edmund S Sabanegh, Jr4


1. Director, Center for Reproductive Medicine, Glickman Urological and Kidney Institute, Cleveland Clinic; 2. Head, Division of Medical Physiology, Stellenbosch University; 3. Medical Student, Case Western Reserve University School of Medicine; 4. Chairman, Department of Urology, Glickman Urological and Kidney Institute, Cleveland Clinic


Abstract


It is well known that being overweight or clinically obese can have adverse effects on health. In the past, little was known about the impact of obesity on male reproductive function. However, several recent studies clearly show that obesity is associated with reduced semen quality and erectile dysfunction, and therefore obesity can be regarded as a cause of male infertility. It is believed that excess fat leads to changes in hormone levels (e.g. adipocytes increase aromatisation of testosterone to oestrogen) as well as dysregulation of the hypothalamus–pituitary–gonadal axis. Higher levels of adipose-derived hormones and adipokines combined with physical disorders can further contribute to obesity-induced infertility. Several treatment options, e.g. lifestyle changes, pharmacological interventions and surgical options, are being explored for their ability to restore fertility in the obese. Urologists and fertility specialists must be more aware of the role obesity plays in the aetiology of male infertility.


Keywords Obesity, male infertility, reproductive hormones, adipose-derived hormones, adipokines, sperm parameters, body mass index


Disclosure: The authors have no conflicts of interest to declare. Received: 17 March 2010 Accepted: 2 June 2010 Citation: European Urological Review, 2010;5(1):60–4 Correspondence: Stefan S du Plessis, Head, Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg 7505, South Africa. E: ssdp@sun.ac.za


Evidence suggests that male fertility is decreasing not only in westernised societies but worldwide. This is evident from various population-based studies as well as from the increasing numbers of couples seeking infertility treatment.1–4


As yet, questions remain as to


the cause of these findings. Several reports have focused on the possible link between obesity and male infertility.4–8


It is speculated


that obesity disrupts male reproduction by impairing semen parameters and reducing secondary sex characteristics.9


It is thus of


importance for urologists and fertility physicians to assess male body composition during the normal fertility work-up and to focus on obesity as an aetiology of male infertility.


Obesity – Definition and Prevalence Obesity is a medical condition in which excess body fat, or white adipose tissue, accumulates in the body.9


more broadly defined as abnormal or excessive fat accumulation that may impair health.


Only a few methods can accurately measure fat content, including underwater weighing and dual-energy X-ray absorptiometry (DEXA), but these methods are not practical and are performed only in research centres with specialised equipment. Therefore, the most commonly used method is the most simple to perform: body mass index (BMI), which is defined as weight in kilograms divided by the square of the height in metres (kg/m2). A BMI >25kg/m2 is considered overweight and a BMI >30kg/m2 is considered to be obese. Waist circumference and the waist-to-hip ratio (WHR) are less commonly used to diagnose obesity. In fact, they may be more accurate in predicting


60


This lifestyle is the key cause of the global increase in overweight and obesity and the reason it is reaching epidemic proportions in several countries. In the US alone, more than 35–40% of the population is believed to have a BMI >30kg/m2.13,14


Once Overweight and obesity are


The global prevalence of obesity has doubled in the past decade, and at this rate it is predicted that almost one billion people will suffer from obesity in the next five years.15


considered to be a problem only of westernised countries, this phenomenon is now dramatically on the increase in developing countries and, specifically, in young children (six to nine years of age).15


Sedentary lifestyles and decreased physical activity combined with an increased intake of energy-dense foods high in fat and sugars lead to an energy imbalance whereby energy consumed exceeds energy expended.9


obesity-related health issues. For males, a waist circumference of 102cm or greater is considered to be unhealthy, while a WHR


Other anthropometrical measurements such as


skin fold thickness, bioelectrical impedance analysis, risk factors and co-morbidities are also used to diagnose obesity.


Obesity-linked Male Infertility – Evidence The effects of obesity on reproductive function have been studied extensively in women, and it is well known that obesity negatively affects female fertility.16,17


Conversely, the effects of obesity on male


fertility have not been comprehensively investigated in the past, and the affects are less apparent. However, recent studies have suggested that there is a connection between obesity and the hypothalamus– pituitary–gonadal (HPG) axis, semen parameters and sexual function.


© TOUCH BRIEFINGS 2010


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