Obesity (overweight) and male fertility

Doctors describe overweight and obesity as excessive fat accumulation that may impair health.

To distinguish between both concepts in adults is used body mass index (BMI). It is marked as a person’s weight in kilograms divided by the square of his height in meters (kg/m2).

For adult men, overweight and obesity are defined as follows[1]:

  • overweight is a BMI ≥ 25
  • obesity is a BMI ≥ 30

Excessive fat deposition is associated with a variety of male fertility issues.

Androgens level alterations 

Doctors describe the hormonal profile of obese males as “hyperestrogenic hypogonadotropic hypogonadism.” Sex steroids provide strict control of spermatogenesis (production and development of sperm cells). These male steroids are regulated by the hypothalamus-pituitary-gonadal axis and Leydig and Sertoli cells located in the testes. 

In turn, obesity can dysregulate hormonal connections. Researches show that high BMI in men leads to reduced sex hormone-binding globulin (SHBG) and, consequently, total and free testosterone levels; estrogen levels become conversely increased because of the aromatization of testosterone[2]. Inhibin B concentrations (a marker of Sertoli cells function) decreases too[3]. The decrease in androgen levels is proportional to the degree of obesity[4]. Scientists report that there is an association between insulin resistance, a predisposition of obesity, and low testosterone levels[5].

Sleep apnea (one of the consequences of excessive weight in males) is suggested to be the other cause of hypoandrogenism. Patients with sleep apnea frequently have fragmented sleep because of upper airway obstruction incidents. In those cases, morning testosterone levels are reduced. 

Eventually, obese men may have erectile dysfunction and diminished libido[6].

Sexual dysfunction

Low androgens, elevated levels of proinflammatory cytokines are responsible for sexual dysfunction in obese men. These changes include weakened libido and erectile dysfunction. Persons with high BMI report higher rates of sexual difficulties caused by their weight. Obese men may consider themselves unattractive. They frequently experience sexual dissatisfaction, lack of sexual desire, enjoyment, and even avoidance of sexual relationships[7].

Overweight is associated with significant impairment in sexual quality of life. 

Lower sperm quality

Body mass index is associated with alterations in sperm parameters. 

Traditional sperm parameters include sperm concentration, sperm motility, and sperm morphology. Overweight is negatively associated with the total motile sperm count and positively related to the percentage of immotile sperm cells[8].

Some studies have presented that males with induced obesity had reduced sperm with normal morphology. Nevertheless, it is essential to consider the negative impact of nutritional or lifestyle factors associated with being overweight rather than a direct effect of obesity. Sperm quality is a significant measure of male fertility, and abnormal sperm parameters correlate with subfertility and infertility. 

The molecular structure and content of the sperm are also pretty vital to the ability of sperm to produce healthy generations. Male obesity enhances sperm DNA damage and induces seminal oxidative stress[9]. In obese men, the scrotum remains in closer contact with surrounding fat tissue, leading to a higher scrotal temperature that may affect epididymis and testicles and strengthen oxidative stress.

These factors can disturb spermatogenesis and lead to male infertility[10].

Pregnancy outcome

There is evidence that male obesity may play a role in reducing fertility and embryo health. 

Some investigations show that couples with an overweight male partner (a female has normal BMI) need more time to conceive than couples with average-weight male partners[11]. Moreover, fertilization chances during in vitro fertilization (IVF) are slighter when a man is obese. Male overweight may impair blastocyst development and reduce live birth outcomes[12]. In addition, scientists found reduced ability of the sperm to bind due to excessive fat accumulation in men.

Indeed, obesity in males is connected with lowered pregnancy rates and a rise in pregnancy loss in couples undergoing infertility treatment. 

Offspring health 

There is a lot of data related to the influence of maternal lifestyle on childʼs health. However, we must also pay attention to paternal health conditions. 

Epidemiology studies have gathered information that obese fathers are more likely to have an obese child[13]. Animal models have shown that high paternal BMI can harm the pancreatic cells of female offspring[14]. Moreover, transmissions of diminished fatherʼs reproductive health to future generations were proved during experiments[15].

Male obesity leads to dysregulation of spermatogenesis. The changed molecular profile of paternal sperm causes altered embryo development and, consequently, offspring diseases.

References

  1. World Health Organization 
  2. Chavarro JE, Toth TL, Wright DL, Meeker JD, Hauser R. Body mass index in relation to semen quality, sperm DNA integrity, and serum reproductive hormone levels among men attending an infertility clinic. Fertil Steril. 2010 May 1;93(7):2222-31. doi: 10.1016/j.fertnstert.2009.01.100.
  3. Martini AC, Molina RI, Ruiz RD, Fiol de Cuneo M. Impacto de la obesidad en la función reproductiva masculina [Obesity and male fertility]. Rev Fac Cien Med Univ Nac Cordoba. 2012;69(2):102-10. Spanish. 
  4. Giagulli VA, Kaufman JM, Vermeulen A. Pathogenesis of the decreased androgen levels in obese men. J Clin Endocrinol Metab. 1994 Oct;79(4):997-1000. doi: 10.1210/jcem.79.4.7962311.
  5. Tsai EC, Matsumoto AM, Fujimoto WY, Boyko EJ. Association of bioavailable, free, and total testosterone with insulin resistance: influence of sex hormone-binding globulin and body fat. Diabetes Care. 2004 Apr;27(4):861-8. doi: 10.2337/diacare.27.4.861. 
  6. Cabler S, Agarwal A, Flint M, du Plessis SS. Obesity: modern man’s fertility nemesis. Asian J Androl. 2010 Jul;12(4):480-9. doi: 10.1038/aja.2010.38.
  7. Kolotkin RL, Binks M, Crosby RD, Østbye T, Gress RE, Adams TD. Obesity and sexual quality of life. Obesity (Silver Spring). 2006 Mar;14(3):472-9. doi: 10.1038/oby.2006.62.
  8. Fatima Hammiche, Joop S.E. Laven, John M. Twigt, Willem P.A. Boellaard, Eric A.P. Steegers, Régine P. Steegers-Theunissen. Body mass index and central adiposity are associated with sperm quality in men of subfertile couples. Human Reproduction, Volume 27, Issue 8, August 2012, Pages 2365–2372, doi:10.1093/humrep/des177.
  9. Tunc O, Bakos HW, Tremellen K. Impact of body mass index on seminal oxidative stress. Andrologia. 2011 Apr;43(2):121-8. doi: 10.1111/j.1439-0272.2009.01032.x.
  10.  Aitken RJ, Baker MA. Oxidative stress, sperm survival and fertility control. Mol Cell Endocrinol. 2006 May 16;250(1-2):66-9. doi: 10.1016/j.mce.2005.12.026.
  11.  Nguyen RH, Wilcox AJ, Skjaerven R, Baird DD. Men’s body mass index and infertility. Hum Reprod. 2007 Sep;22(9):2488-93. doi: 10.1093/humrep/dem139. 
  12.  Hassan W. Bakos, Richard C. Henshaw, Megan Mitchell, Michelle Lane. Paternal body mass index is associated with decreased blastocyst development and reduced live birth rates following assisted reproductive technology. Fertility and Sterility, Volume 95, Issue 5, 2011, Pages 1700-1704, ISSN 0015-0282. doi:10.1016/j.fertnstert.2010.11.044.
  13.  Li L, Law C, Lo Conte R, Power C. Intergenerational influences on childhood body mass index: the effect of parental body mass index trajectories. Am J Clin Nutr. 2009 Feb;89(2):551-7. doi: 10.3945/ajcn.2008.26759.
  14.  Ng SF, Lin RC, Laybutt DR, Barres R, Owens JA, Morris MJ. Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring. Nature. 2010 Oct 21;467(7318):963-6. doi: 10.1038/nature09491.
  15. Fullston T, Palmer NO, Owens JA, Mitchell M, Bakos HW, Lane M. Diet-induced paternal obesity in the absence of diabetes diminishes the reproductive health of two subsequent generations of mice. Hum Reprod. 2012 May;27(5):1391-400. doi: 10.1093/humrep/des030.