Testosterone therapy: who actually needs it, and the fertility cost
September 29, 2026 · 15 min read
Kyle Gillett says young men rarely need TRT, Michael Eisenberg warns it can shut down fertility, and Attia and Huberman discuss when it makes sense later in life. It helps men separate genuine deficiency from marketing.
The rules, numbers and steps worth keeping in front of you.
- Kyle Gillett: for young men with normal levels, the benefit of testosterone almost never outweighs the harm.
- Order of operations: blood work, lifestyle, supplements, then prescription drugs with a doctor.
- Test total testosterone with SHBG, or free testosterone; free is typically about 2 percent of total.
- Gillett: symptoms mislead, so labs come first.
- Gillett: regularly training vigorously for longer than an hour is not hormonally helpful.
- Gillett: alcohol, smoked cannabis and nicotine all harm testosterone.
- Michael Eisenberg: about one in 20 infertile men are infertile because of testosterone.
- Eisenberg: outside testosterone shuts down LH and FSH and halts sperm production.
- Eisenberg: freeze sperm first, or use hCG at 500 to 1,000 units every other day.
- Eisenberg: sperm take two to three months to make, so recovery takes months.
- Eisenberg: decades of data show therapy does not raise prostate cancer risk.
- Eisenberg: fewer than 10 percent of erectile dysfunction cases are hormonal; it can signal vascular disease.
- Doses: Gillett starts at 100 to 120 milligrams a week; Peter Attia usually stays at or under 100.
- Therapy should be started and monitored only by an experienced physician.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.