Testosterone therapy is booming, but how much of it is medically necessary, and how much is hype? Sean Aylmer speaks with Dr Zac Turner about exogenous testosterone, what it actually is, and what the major TRAVERSE clinical trial found about heart risk and safety.

They discuss why falling testosterone levels are common as we age, the surprising role sleep and stress play in suppressing hormone production, and why many people may be able to improve levels naturally before turning to replacement therapy.