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:
- 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
- Sexual dysfunction
- Lower sperm quality
- Pregnancy outcome
- Offspring health
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. Inhibin B concentrations (a marker of Sertoli cells function) decreases too. The decrease in androgen levels is proportional to the degree of obesity. Scientists report that there is an association between insulin resistance, a predisposition of obesity, and low testosterone levels.
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.
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.
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.
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. 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.
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. 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. 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.
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. Animal models have shown that high paternal BMI can harm the pancreatic cells of female offspring. Moreover, transmissions of diminished fatherʼs reproductive health to future generations were proved during experiments.
Male obesity leads to dysregulation of spermatogenesis. The changed molecular profile of paternal sperm causes altered embryo development and, consequently, offspring diseases.
- World Health Organization
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