Study finds boys with obesity at higher risk of becoming infertile men

Italian researchers have discovered a potential link between obesity in boys and reduced testicle size, which may increase the risk of infertility in these young men later in life.

The study included boys aged 2 to 18 who were recommended to the Pediatric Endocrinology Unit at the University of Catania in Sicily for weight management. The researchers observed that boys with normal insulin levels displayed up to double the testicular volume in comparison to boys with high insulin levels.

Boys who had overweight or obesity and displayed hyperinsulinemia, or insulin resistance, generally had smaller testicles than other boys, according to the researchers. This condition, referred to as “testicular hypotrophy,” is known to elevate the risk of infertility in males.

Dr. Alex Robles, a fertility specialist at the Columbia University Fertility Center in New York, explained to Medical News Today that testicular volume is directly linked to semen profiles and is generally a reliable indicator of hormonal function. He added that infertile men typically have a smaller testicular volume compared to fertile men. This is also seen in men who consume exogenous anabolic steroids, leading to a reduction in the production of endogenous testosterone, testicular size, and sperm production.

Co-author of the study, Rossella Cannarella, a research assistant at the University of Catania in Italy, noted that the impact of obesity and related metabolic disorders on testicular growth is not thoroughly understood, despite the global rise in childhood obesity. The study, published in the European Journal of Endocrinology, found that having overweight or obesity was associated with a decrease in testicular volume during peri-puberty. Additionally, obesity-related conditions like hyperinsulinemia and insulin resistance were found to affect testicular volume both before and after puberty.

Cannarella suggests that more careful management of body weight during childhood could be a preventive strategy for preserving testicular function in adulthood.

Male infertility is believed to contribute to approximately half of all cases of couple infertility, but the causes often remain unknown. Research has shown a decrease in sperm concentration and count over the past four decades, while childhood obesity rates have increased dramatically. It is estimated that by age 35, 60% of children aged 2 to 19 will have obesity.

Dr. Robles also highlighted the significant connection between obesity and fertility issues, particularly in women. Obesity can disrupt the hormonal balance needed for egg growth, development, and ovulation. Similarly, in men, obesity can interfere with the hormones that assist in testosterone production by the testicles. Low testosterone is linked to reduced sperm production and quality.

However, Dr. Jagdish Khubchandani, a professor of public health at New Mexico State University, warned that while the study showed promise in highlighting the connection between obesity, metabolism, and testicular volume, it had limitations. The study was cross-sectional with a small population, so it could not establish a cause-and-effect relationship between testicular size, obesity, and risk of infertility.

Dr. Khubchandani emphasised that although there is a correlation between the global rise in obesity and the decline in sperm count, it doesn’t necessarily mean the two are directly linked. Factors such as diet and environment could independently influence obesity, metabolism, and reproductive health.

Dr. Robles agreed that while the findings of the retrospective review are plausible given the known impacts of obesity on hormonal regulation and testosterone levels, more research is necessary to determine if weight loss is an effective treatment for improving testicular volume. Previous research suggests that weight loss can improve hormonal health in men with obesity by restoring natural testosterone levels, which can subsequently increase testicular volume and sperm production.

Dr. Khubchandani highlighted the importance of early childhood interventions to address many health issues linked to obesity, including those discussed in this study. He added that obesity is a global pandemic and a leading cause of numerous health problems worldwide.