Male infertility: How obesity in boys can increase the risk

  • Researchers say boys who are obese may face a higher risk of infertility as men.
  • They say obesity can lead to shrunken testicles, which can affect sperm count.
  • Experts say intervention programs are needed to combat the increase in childhood obesity.

Obesity in boys may be linked to shrunken testicles and result in a higher risk of infertility for young men, Italian researchers report.

In their study of boys ages 2 to 18 who were referred to the Unit of Pediatric Endocrinology at the University of Catania in Sicily for weight control, researchers found that those with normal insulin levels had as much as two times higher testicular volume than boys with elevated insulin levels.

In the boys who were overweight or had obesity, hyperinsulinemia (insulin resistance) tended to lower testicular volume compared to other boys, researchers said.

This “testicular hypotrophy,” researchers said, is known to increase risk of infertility in men.

“Testicular volume does have a direct relationship to semen profiles and tends to be a good predictor of hormonal function,” Dr. Alex Robles, a fertility expert at the Columbia University Fertility Center in New York, told Medical News Today.

“There is data that infertile men on average have a smaller testicular volume compared to fertile men,” he added. “We can see this in men taking exogenous anabolic steroids as well. These individuals stop producing their own endogenous testosterone which will reduce testicular size/volume and sperm production.”

“Although the prevalence of childhood obesity is increasing worldwide, the impact of obesity and associated metabolic disorders on testicular growth is not well known,” said Rossella Cannarella, a research assistant at the University of Catania in Italy and a co-author of the study published in the European Journal of Endrocrinology.

“We found that being overweight or obese was associated with a lower peri-pubertal testicular volume. In addition, obesity-related comorbidities, such as hyperinsulinemia and insulin resistance, have been found to influence testicular volume in pre- and post-puberty,” she added.

“Therefore, we speculate that more careful control of body weight in childhood could represent a prevention strategy for maintaining testicular function later in life,” Cannarella said.

Obesity and infertility

Male infertility is estimated to contribute to about half of all cases of couple infertility, but the reasons for it are often unclear.

Other studies have shown a decrease in sperm concentration and count over the past 40 years.

At the same time, the rate of childhood obesity has risen sharply. An estimated 60% of children ages 2 to 19 will be obese by age 35.

“There is a fairly significant link between obesity and fertility, especially in females,” said Robles. “Obesity and excess fat mass can disrupt all of the hormones necessary for the growth and development of an egg and subsequent ovulation. Similarly in men, obesity can disrupt the hormones that help the testicles produce testosterone. Low testosterone is linked to decreased sperm production and decreased sperm quality.”

Reaction to the infertility and obesity study

Dr. Jagdish Khubchandani, a professor of public health at New Mexico State University, told Medical News Today that the study “has promise in highlighting the link between obesity, metabolism, and testicular volume.”

However, Khubchandani said that while the study was well-controlled and included a good range of markers for obesity and metabolism, the population studied was small and — because it is cross-sectional — no cause-and-effect relationship can be established among testicular size, obesity, and infertility risk.

“If the only good finding is an association found in this study, we have many prior studies that show how obesity may affect fertility,” Khubchandani said.

Like the study authors, Khubchandani noted that “sperm count has declined across much of the world in the past few decades.”

“Obesity has increased at the same time,” he said. “But we cannot claim that the two are related. What mediates or moderates this relationship? Or, is it the food and environment that independently influence obesity, metabolism, and reproductive health?”

Looking ahead

Although this was a retrospective review, said Robles, the findings are plausible based on what we know about obesity, hormonal regulation, and testosterone levels.

“With that said, more research is needed to know if these results can be replicated and if weight loss is an effective treatment option for improving testicular volume,” he said.

“Obesity is a pandemic, a leading killer across the world, and linked to most prevalent health problems across the world,” said Khubchandani. “Early childhood interventions could address many of these issues, including the ones discussed in this study.”

Robles added that past research shows “that losing weight can be a potential treatment option for improving the hormonal health of obese men by restoring natural testosterone levels, which in turn can increase testicular volume and sperm production.”

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