Excess weight and obesity may be contributing to a decline in semen quality, an important measure of male fertility, according to recent research from China. This includes lower sperm counts and other critical parameters.
“The continuous decline of human semen quality during the past decades has drawn much concern globally,” notes epidemiologist Yingxin Li from Sun Yat-sen University and colleagues in their published paper. Past studies have hinted at a connection between abnormal BMI and declining semen quality, but results have been inconsistent.
SYSTEMATIC REVIEW AND META-ANALYSIS
Li and the team conducted a comprehensive review and meta-analysis of 50 previous studies, covering a total of 71,337 men. These studies measured the association between BMI and several parameters of semen quality.
KEY FINDINGS
The findings revealed that obesity and overweight were significantly linked to a decline in semen quality. The reduction in semen quality was more pronounced in men with obesity compared to those who were overweight.
- Obese Men: Lower semen volume, lower total sperm count, and reduced sperm motility (the number of moving sperm) compared with men with a healthy BMI.
- Overweight Men: Lower semen volume and reduced sperm motility compared with men with a healthy BMI, though the difference was less significant.
A systematic review like this doesn’t prove that excess weight causes a decline in semen quality. However, it highlights patterns that researchers can further investigate, including the biological mechanisms at play.
POTENTIAL BIOLOGICAL FACTORS
The study did not closely examine the reasons behind the association, but previous research has suggested several factors:
- Toxins in fatty tissue
- Hormonal imbalances
- Higher body temperature
CHALLENGES IN RESEARCH
Many variables can affect semen quality, including environmental pollution, smoking, age, illness, and diet. Isolating each factor from the others is challenging. This complexity requires more extended research periods. Limitations in the reviewed studies included taking only one semen sample in many cases and using self-reported BMI rather than professional assessments.
IMPORTANCE OF MAINTAINING A HEALTHY WEIGHT
Previous studies have shown that lifestyle changes and weight loss can improve semen quality. This new research supports these findings.
“Our findings highlight the potential and importance of maintaining a normal weight to prevent the decline of semen quality and improve male fertility,” write the authors.
