Does a man's waist size determine sperm quality? !

The research team of Ghiyas Shayeb of the University of Aberdeen in the UK analyzed the sperm of more than 5,000 Scottish men and divided them into different groups according to their body mass index (BMI), which is weight (kg) divided by height (m) squared. BMI between 20-25 is normal weight, 25-29 is overweight, and 30 and above is obese.

The results showed that men with a BMI of 20-25 had a higher level of normal sperm, while overweight and obese men not only had less semen volume (number of sperm), but also had a low number of normal sperm. The probability of obese men having fewer sperm was over 60%, and the probability of having abnormal sperm was over 40%. The situation of overweight and obese men was similar. In their study, Shayebu et al. excluded other factors that may affect sperm count, such as smoking, drinking, drug abuse, and age, and confirmed that obesity does affect sperm count and sperm quality.

Why does obesity affect the quantity and quality of men's sperm?

There are some theories and hypotheses, among which three are more recognized:

First, adipose tissue affects sex hormone metabolism, which may hinder sperm production and sperm quality.

Second, temperature may have a negative impact on sperm production.

The normal human body temperature is around 37°C, and the optimal temperature for sperm production is 2°C lower than normal. Obese men have more fat, so their body temperature is higher than normal people. The high temperature of the scrotum will directly affect the spermatogenic ability of the testicles, resulting in a decrease in sperm production; even if the amount of sperm production is not affected, the quality of the sperm produced will be affected.

3. Diabetic patients suffer from more sperm damage.

In addition, obesity can lead to diabetes or latent diabetes, which can also damage sperm and thus affect male fertility. This has been proven by other researchers. Cohen Meridis of Queen's University Belfast treated 40 men who were not overweight but had diabetes and found that due to diabetes, the patients had higher levels of sugar in their blood, which damaged the DNA in their sperm. They found that the probability of sperm damage in diabetics was twice that of normal men without diabetes.

Despite this, researchers still cannot confirm that obesity will definitely cause infertility, as it depends on other factors. For example, if an obese man marries a normal woman, the obese man's reproductive function will be compensated by the other party, so it does not necessarily lead to infertility. However, if an obese man marries an obese woman, the obesity of the two will be superimposed and form an amplification effect, causing infertility.