Overweight Boys and Puberty
Jon Barron has spoken repeatedly over the last 20 years about the increasing early onset of puberty in girls. We know that one important factor in this is excess weight, since it influences hormone production. But are boys who are heavy affected in the same way? New research posed this very question and the answer is that the onset of puberty does appear to be affected, but not in exactly the same way as it is for girls.
The study, which was conducted at the University of Michigan in Ann Arbor, found that boys who are overweight tend to go through puberty earlier than usual but boys who are obese tend to go through puberty at a later point than what's typical for normal weight boys.1 The subjects were 3,872 boys between the ages of six and 16 who were tracked through childhood and adolescence. The stages of puberty were noted to determine the start and finish of the process.
The scientists expected that the influence of the sex hormone estrogen, which is present in greater quantities when there are large accumulations of fat in the body, would run counter to the effects it has on females. In other words, a 2013 study at Cincinnati Children's Hospital Medical Center in Ohio showed that girls who are overweight and obese experience puberty earlier than their normal weight peers due to higher levels of reproductive hormones.2 However, in boys, the balance of hormones is different--they need testosterone, not estrogen, for puberty--so the researchers anticipated that overweight or obese males would instead face delays in puberty because of abundant estrogen.
Based on the data, they were partially correct. While the boys who had a body-mass index (BMI) that placed them in the obese range were, as expected, beginning and ending puberty at a later age, those boys with a BMI that categorized them as overweight actually entered and completed puberty at an earlier point than their normal-weight counterparts.
The numbers held true for both black and white youths and although they weren't vastly different from the standard ages, they were measurably distinct. Overweight white boys began the first stage of puberty at an average age of 9.3 years old, versus beginning at 10 years old in boys of normal weight. In addition, the overweight white boys tended to finish puberty earlier, at an average age of 14.5 years old rather than the average of 15.2 years old found in normal weight boys.
In contrast, the obese black and white participants went through puberty later than their thinner peers. Obese black boys were shown to complete puberty at an average age of 15.4 years old, whereas normal-weight boys were typically finished at 14.5 years old. And the investigators did not have an answer as to why the timing of puberty would be different in overweight boys compared to obese boys except to posit that perhaps smaller extra amounts of estrogen spur early development while greater quantities of estrogen produce a delay.
It is curious that the results were inconsistent, and even more so when the scientists included Hispanic versus non-Hispanic categories. Weight did not appear to influence the timing of the onset or completion of puberty in boys identified as Hispanic, which could indicate a discrepancy in the way the research was conducted.
Nevertheless, there is evidence here that adds to the existing information on how excess weight can create hormonal imbalances at a very young age and produce an impact on puberty, and early puberty has been linked with depression.3 Not to mention overweight and obese children are at higher risk for numerous conditions such as diabetes, high blood pressure, and asthma. If you've got young kids, one of the best things you can do is help them maintain--or reach, if need be--a healthy weight. And when talking about estrogen and puberty, it should not be forgotten that various toxins in common use have estrogenic effects, particularly endocrine disrupters like BPA, which shows up in plastic water bottles, baby bottles, and the lining of many of the canned foods on our shelves. In any case, by learning about the benefits of nutrition, regularly detoxing, and physical activity, your children will develop great habits that they can stick with throughout their lives.
- 1. Lee, Joyce M.; et al. "Timing of Puberty in Overweight Versus Obese Boys." Pediatrics. February 2016. Accessed 3 February 2016. http://pediatrics.aappublications.org/content/early/2016/01/25/peds.2015-0164
- 2. Biro, Frank M.; et al. "Onset of Breast Development in a Longitudinal Cohort." Pediatrics. October 2013. Accessed 4 February 2016. http://pediatrics.aappublications.org/content/early/2013/10/30/peds.2012-3773.full.pdf+html
- 3. Rudolph, Karen D. and Flynn, Megan. "Childhood adversity and youth depression: Influence of gender and pubertal status." Development and Psychopathology. 25 April 2007. Accessed 4 February 2016. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1003064&fulltextType=RA&fileId=S0954579407070241