Boys who are overweight or obese have smaller testicles than their normal-sized peers, a study has found.
Scientists in Italy, who carried out the research, warned the added weight also leads to a higher risk of lower sperm counts and infertility in adult life.
In the study, overweight and obese children aged nine to 14 — when they go through puberty — had testicles about 50 percent smaller than those who were normal-sized.
Among youngsters with hyperinsulinemia, high insulin levels and a precursor to type 2 diabetes, their testicles were up to half the size of their peers.
Being overweight or obese can restrict the growth of the testicles, scientists warned, because it can disrupt hormones and lead to heat stress on the scrotum.
Children’s weight status was calculated using the body mass index, which divides weight by height. A higher score puts a child into the overweight or obese range.
The study included 268 children who were overweight or obese (Stock image)
Scientists have been raising the alarm over plummeting male sperm counts for years, which some have now warned ‘threaten human survival’.
Back in 1973, the average sperm count was about 104million per milliliter, studies show.
But, by 2019, this had fallen to just 49million — halving in under 50 years.
Expanding waistlines, sedentary lifestyles and even exposure to chemicals like pesticides have all been blamed for the shift.
Dr Rossella Cannarella, a fertility expert at the University of Catania in Sicily, Italy, which carried out the research, warned obese boys were at higher risk of infertility in adulthood.
She said: ‘Those with overweight or obesity, hyperinsulinemia, or insulin resistance displayed lower testicular volume than their healthy peers
‘We speculate that more careful control of body weight in childhood could be a prevention strategy for maintaining testicular function later in life.’
The press release adds that the paper ‘indicates that overweight boys tend to have lower testicular volume, putting them at risk for infertility in adulthood’.
For the study, scientists looked at data on testicular volume for children referred to the university’s Pediatric Endocrinology Unit for weight management.
They were compared to a group of children of a healthy weight who also had their testicle size measured.
The study looked at 268 children, of which 206 fell into the overweight, obese or severely obese categories while the rest were a normal weight.
Children were split into three groups, from those aged under nine years — pre-puberty — nine to 14 years old — during puberty — and 14 to 16 years old — post-puberty.
Results showed that obese or overweight children in the nine to 14-year-old age group had significantly smaller testicles than their normal-sized peers.
Those 14 to 16 years old and with hyperinsulinemia had testicles up to half the size of their healthy peers.
Adolescence is critical for testicular development because they undergo major growth to produce sperm.
But previous research has shown that being overweight or obese can disrupt this because fat cells can interfere with the hormone balance in the body.
The excess weight may also lead to heat stress on the testicles or being kept above the 95 to 96F needed, which can harm development.
In the study, the scientists suggested overweight or obese children likely had lower levels of the hormone inhibin B, which is made by the testicles and essential for stimulating the growth of sperm-producing cells.
They also said that hyperinsulinemia could inhibit the growth of Sertoli cells in the testes, which are also essential for manufacturing sperm.
Dr Cannarella added: ‘In this study, we found that being overweight or obese was associated with a lower peri-pubertal testicular volume.’
The study was published in the European Journal of Endocrinology.