Decreased fertility in obese men

Obesity can affect fertility and sexual behavior

According to the current report on nutrition of the German Nutrition Society (DGE), 67 percent of men are overweight, 23 percent are even obese. Several studies have revealed that this has consequences not only for individual health, but also for fertility and sexual behavior.

Sperm is affected

A study by the Medical Center of Leipzig investigated between 1995 and 2005 the sperm of over 2000 men microscopically (1). The resulting "spermiograms" led to interesting insights in the relationship between body weight and fertility of men. The study leader Prof. Dr. Uwe Paasch of the Department of Dermatology, Venereology (sexually transmitted diseases) and Allergy, and Head of the “Training Center of the European Academy of Andrology” at the University of Leipzig explains: "Not only the number of sperm is reduced in obese men, but the sperm is deformed and partially impaired in their performance." These changes probably lead to reduced fertility.

Low testosterone level

In obese men the concentration of the male sex hormone testosterone in the blood is significantly lower than in normal weight people. Especially a decreased production of testosterone leads to a disorder of sperm maturation and a decreased libido and thus affects sexual activities. At the obesity clinic of the IFB at the University Hospital of Leipzig this problem is already known, as the head of the obesity clinic, Prof. Dr. Mathias Fasshauer, says: "Obese males generally have lower levels of the male sex hormone testosterone, which plays an important role in fertility and sexual behavior. The reasons for this deficiency are scientifically not yet fully clarified."

In addition, the existing fat cells convert the male hormone testosterone into the female sex hormone estrogen. The excess of female sex hormone on the other hand leads to reduced sperm production (2). Furthermore, an increased blood pressure and high cholesterol level can damage the blood vessels, which also affect the blood supply to the penis and thus the ability to have erections.

Help by wish for children

Using testosterone, circulation-promoting remedies (e.g. phosphodiesterase-5 inhibitor) or antihypertensive drugs may partially help obese men with regard to the production of sperm (spermatogenesis) and to erectile disorders respectively diminished libido. A therapy of the reduced number of sperm or decreased performance and deformations has to be looked into in each individual case. Finally, the relatively complex in vitro fertilization methods can be used, but they are not always successful.

Obese men with reduced fertility should also try to reduce their weight and participate for example in an obesity treatment program. Although unique study results are still pending, it is assumed that a reduction of the weight has a positive effect on fertility. This is the case for obese women, who want to have babies, and who became pregnant more easily after weight loss. The IFB AdiposityDiseases Leipzig offers support in weight loss in its obesity clinics.

Martin Liborak

(1) Paasch et al: Obesity and age affect male fertility potential. In: Fertility and Sterility Vol. 94, No. 7, Dezember 2010; S. 2898-2901
(2) Sharpe et al: Environmental/lifestyle effects on spermatogenesis. In: Phil. Trans. R. Soc. B (2010) 365, 1697–1712

Keywords: kids & family, associated diseases