> In this analysis we observed little evidence of age-independent trends with respect to most covariate factors; notable exceptions to this rule, however, were the aforementioned increases in relative weight, as well as population-level changes in the prevalence of smoking and the concurrent use of multiple medications (polypharmacy). There were substantial age-specific increases in obesity and polypharmacy over the course of study follow-up<p>Obesity is still a huge contributor to reduced testosterone, and this study doesn’t disagree with that. It’s such a well-known effect that it’s one of the first things the authors note and try to account for. These studies are trying to identify factors beyond obesity and reduced physical activity, but it’s difficult to tell if they’ve developed an accurate model to subtract those effects from their study.<p>While it’s possible that environmental toxins like BPA can contribute to neuroendocrine disruption and should be investigated, lifestyle factors are still at the top of the list of things people can adjust to influence their own testosterone levels.