Weight a Factor in When Puberty Hits Boys
A study published in the journal Pediatrics has shed some light on how being overweight influences what age a boy will go through puberty. But there are key developmental differences between normal weight, overweight and obese adolescents.
Lead author Joyce Lee, associate professor and pediatric endocrinologist at the University of Michigan Medical School, notes that their findings suggest excess weight appears to have different effects on boys compared with girls:
"In girls, excess weight is associated with an earlier onset of puberty, but for boys we saw a mixed picture. Overweight boys had an earlier onset of puberty, while obese boys experienced a later onset of puberty, compared with normal weight boys."
The team re-analyzed recent community-based data on puberty in more than 3,600 boys aged 6-to-16. The data covered white (49.9 percent), black (25.8 percent) and Hispanic (24.3 percent) boys. They grouped the boys -- based on their body mass index (BMI) -- into normal weight, overweight or obese, and compared age against Tanner stage in each group. Tanner stages rate different levels of sexual maturity.
All the boys in the study experienced puberty within the normal age range. However, for white and black boys, puberty occurred earlier in overweight compared with normal weight boys, and occurred later in obese compared with overweight boys. The study found no significant differences for Hispanic boys.
The study did not investigate the causes of these differences. However, the researchers say previous studies have found that carrying too much body fat can lead to over-production of the female sex hormone estrogen in boys, and they speculate that perhaps an excess of estrogen delays puberty in obese, but not overweight boys.