Lack of hard physical labor, combined with increasing average caloric intake may contribute to lower average muscle mass & total testosterone while still mainta

Lack of hard physical labor, combined with increasing average caloric intake may contribute to lower average muscle mass & total testosterone while still maintaining a "normal" BMI. I don't have evidence to support this, but this is my guess for falling testosterone within the "normal" BMI range over time (in addition to the effect of environmental pollutants on hormones).