Obesity has long been understood as negatively impacting male fertility, but new research uncovered the mechanisms behind this observed phenomenon.

A paper outlining the results of a study on male obesity and compromised fertility was published on May 25 in the peer-reviewed journal Basic and Clinical Andrology.

An Iranian team of researchers collected semen samples from 64 men under the age of 45, half being clinically obese (a BMI over 30) and half having a healthy weight (a BMI of 18.5 to 25). All participants were without any known disease and refrained from unhealthy lifestyle practices such as smoking or drinking alcohol.

By testing the men’s sperm for abnormalities, the researchers found that obesity was directly linked to poor vitality, volume, count, and motility.

These findings are supported by previous studies into obesity and infertility.

For instance, a 2012 study found that obese men are 42% more likely than those at a healthy weight to have a low sperm count and 81% more likely to produce no sperm at all.

Yet the Iranian team suggested that it had found exactly how obesity adversely affects sperm.

Overall, obesity is believed to negatively influence steroidogenesis, which is the process of steroid hormone production, and spermatogenesis, which is the development of mature sperm cells.

Hormone imbalances at the hypothalamic-pituitary level can lead to damaged and abnormal sperm as well as trigger cell death.

Indirectly, obesity can further contribute to these mechanisms by producing higher levels of oxidative stress and inflammation in the body.

In the paper, the researchers highlight the need to conduct further research into these mechanisms in order to develop therapies or preventative protocols to limit the effects of obesity on sperm parameters.

For instance, obesity is associated with the shortened length of telomeres, which are the repetitive nucleotide sequences located at the ends of chromosomes within sperm cells.

The relationship between this risk of shortened sperm telomere length — and thus less DNA integrity — needs to be highlighted in future research, according to the paper’s authors.

The consequences of obesity on male fertility are serious, especially given that the World Obesity Federation recently projected that 51% of the global population — over 4 billion — will be obese by 2035, as The Dallas Express reported.

As the rates of obesity climb among adults and children worldwide, researchers like this team in Tehran are making new discoveries about the epidemic’s widespread effects.

Female obesity has been linked not only to deficiencies in the production of breast milk but also to maternal mortality, the rate of which in Texas is higher than the national average.

Moreover, as The Dallas Express reported, obesity is not just a health issue but also one of national security.

A study from the World Health Organization revealed significant increases in U.S. soldiers’ BMIs during the COVID-19 pandemic, with 26.7% of those studied going from healthy to overweight and 15.6% from overweight to obese.