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Does obesity cause infertility in men ?

Does obesity cause infertility in men

According to the World Health Organization, more than 650 million adults worldwide are obese. As a result of its rapid spread in developing countries, obesity has become a major public health problem of concern. It is estimated that about 30% of the population of the Arab world is obese.

Whereas, a recent Chinese study found a strong relationship between obesity, poor fertility and male infertility, through testicular inflammation that affects the quality of sperm.

Does obesity cause infertility in men ?

Researchers at the Medical College of Shanghai University of China shed light on how obesity may contribute to male infertility, as they found a relationship between it and infertility.

Men who are obese are more likely to have sleep apnea. This disorder is characterized by the temporary stopping of breathing during sleep, which causes an interruption of testosterone production. Also, testosterone levels drop right after waking, which can reduce a man's interest in participating in sexual activity. 

As a result of many factors, obesity appears to contribute to male infertility, as high BMI increases and exacerbates the negative effects of low testosterone levels and decreased semen quality.

so lett's see how does BMI affect fertility ?

1- Disruption of endocrine glands

Typically, men who are obese and infertile have low levels of testosterone and high levels of estrogen in the blood. Decreased androgens, especially testosterone, are proportional to obesity. Increased levels of the female hormones estrone and estradiol are due to the increased peripheral transformation of the rings in androgens into aromatic rings. Also, an increased amount of white adipose tissue contributes to an increase in estrogen levels. The change in the ratio of testosterone to estrogen adversely affects the hypothalamic-pituitary-genital axis, which disrupts the negative feedback loop (which is affected by low testosterone) and causes a decrease in the number of sperms.

 Other hormones are also affected. Men with a high body mass index (BMI) have lower levels of sex hormone binding globulin. Sex hormone binding globulin is involved in spermatogenesis and the functioning of the Sertoli cell. Likewise, levels of the hormone leptin are higher in men who suffer from obesity and infertility often and are less high in men who are obese but not sterile. Leptin is excreted by the body's white adipose tissue, so its serum levels correlate with the amount of body fat. The elevation of the hormone leptin suppresses the production of testosterone by the Leydig cells.

2- Insulin resistance

Secondary hypogonadism most often occurs in obese men with type 2 diabetes as a result of their insulin resistance. Insulin resistance is thought to disrupt the hypothalamic-pituitary-genital axis through mechanisms that are not fully understood. Likewise, high insulin resistance is independently associated with low testosterone levels. Obesity is one of the main risk factors for the development of type 2 diabetes, and difficulty in childbearing is one of the main health risks associated with it.

3- Metabolic syndrome

Obesity, along with many other factors such as high blood pressure, high plasma glucose and cholesterol, contribute to the development of metabolic syndrome. Metabolic syndrome increases the risk of diabetes, but it is also closely associated with hypogonadism and erectile dysfunction. Not all men with erectile dysfunction are infertile, but maintaining an erection is one of the difficulties for men who have difficulty conceiving.

 One study found that 27% of men who are infertile have erectile dysfunction. Moreover, it has been found that people with erectile dysfunction are more likely to suffer from being overweight or obese. Men who suffer from obesity and metabolic syndrome often have an increase in blood insulin and an increase in blood sugar (glucose), which may negatively affect the quantity and quality of sperm.

4-Oxidative stress

  Obesity increases the production of reactive oxygen species that harm the genetic material inside sperm cells. A higher BMI is associated with increased oxidative stress, causing an increased production of reactive oxygen species.