Results of the study showed a decrease in serum Testosterone based on year of birth versus age or lifestyle factors. This means despite healthy or unhealthy lifestyle, men born between a certain range of years (more recent) are experiencing lower serum testosterone than in the past.

 

Symptoms of low testosterone include: anxiety, poor sleep, low motivation, low energy, fatigue, depression, low libido, erectile dysfunction, weight gain

 

"Conclusions: These results indicate that recent years have seen a substantial, and as yet unrecognized, age-independent population level decrease in [testosterone] in American men, potentially attributable to birth cohort differences or to health or environmental effects not captured in observed data. (J Clin Endocrinol Metab 92: 196 –202, 2007)"

 

Download the PDF: A Population-Level Decline in Serum Testosterone Levels in American Men