MODERATE-HIGH overall, per-claim stratified.
HIGH: Adiposity reduction raises endogenous T in overweight men. Sleep restriction lowers T fast. Confirmed hypogonadism benefits from selective testosterone replacement. Most over-the-counter "T-boosters" do not raise T in eugonadal men.
MODERATE: Ashwagandha (KSM-66, Sensoril) in stressed or overweight men. Vitamin D correction in insufficient men. Zinc correction in marginally deficient men. Resistance training (indirect via body composition).
LOW: Tribulus, D-aspartic acid (outside narrow window), ZMA, turkesterone for eugonadal optimization.
DEBUNKED: Tongkat ali for eugonadal men (works only in ADAM-symptomatic subset). Fenugreek for testosterone in healthy men. Maca for testosterone elevation.
What would change my mind on the "9 in 10 don't work" claim
A 12-month, independently-funded, double-blind, placebo-controlled trial of at least 200 healthy eugonadal men (baseline total testosterone 12 to 18 nmol/L, normal weight, normal sleep, replete vitamin D and zinc, non-stressed) testing a named over-the-counter "T-booster" against placebo, with primary endpoint of 8 a.m. fasted total testosterone by LC-MS/MS, showing a ≥15% elevation above placebo at 6 and 12 months. That trial does not exist for any over-the-counter ingredient currently in the category.
What would change my mind on the industry-funded ashwagandha trials
A blinded independent replication of the Lopresti 2019 trial (overweight aging men, KSM-66 600 mg per day, 8 weeks) funded by a non-manufacturer source, showing a similar or larger total testosterone elevation. Until that trial runs, the direction is plausible but the magnitude is almost certainly overstated.
