Hey that looks like it's going back up! To be critical on this - also curious what source that comes from, testosterone level checks are not common on healthy routine blood tests and I wonder if they were at one point and aren't now. Also pair that alongside obesity rates.
Fat tissue consumes testosterone, excess adipose makes _free_ testosterone appear lower on tests, full stop. It doesn't mean anything necessarily. It also is completely independent of muscle mass. Also what suppresses testosterone hormone production the most, is stress (and related conditions).
That graph could be an opposite coloration predicate equally valid.
