Testosterone

An overview of testosterone: what it is, what it does, how levels change with age, and the risks of artificial boosters. Based on a bodybuilding article from around 2000, updated where the information has since changed.

The basics

• Testosterone is a steroid hormone made mainly in the testes (and in small amounts in the ovaries and adrenal glands). It belongs to the androgens, alongside DHT, DHEA and androstenedione.
• Men produce about 7 mg a day, with typical blood levels around 300–1,000 ng/dL. Women produce roughly a fifteenth of that.
• It's made from cholesterol through a chain of steps. About 96–98% in the blood is bound to proteins (albumin and SHBG); the 2–4% that's free is considered the most active.
• Levels rise and fall through the day, so one blood test is only a snapshot.
• Production surges at puberty, peaks in early adulthood, and gradually declines from your 30s. By 80, levels may be about a third of their peak.

What it does in men

• Development at puberty: genital growth, deeper voice, body and facial hair.
• Sperm production and libido.
• Muscle growth (more protein synthesis), bone density and red blood cell production.
• Higher resting metabolism.
• Thicker, oilier skin (sometimes acne) and, in some men, hair loss on the scalp.

In tissues, some testosterone is converted to the more potent DHT, and some to oestrogen, especially in body fat. That's one reason excess fat is linked to lower testosterone.

Supporting healthy levels naturally

• Lift heavy and stay active (see The ONLY 4 Exercises You Need to Grow Stronger, HIIT).
• Keep body fat in a healthy range.
• Sleep 7–9 hours.
• Eat enough protein, healthy fats and overall calories; avoid crash dieting.
• Manage stress and limit alcohol.
• If you have symptoms of low testosterone (fatigue, low libido, loss of muscle), see a doctor for proper blood tests rather than self-medicating.

Steroids and "prohormones"

• Anabolic-androgenic steroids (AAS) are synthetic versions of testosterone. A few have medical uses (for muscle wasting and osteoporosis), but misuse can cause lower "good" cholesterol, testicular shrinkage, reduced fertility, prostate problems, liver damage (especially with oral types), breast tissue growth in men, acne and suppression of your own hormone production.
• The original article promoted over-the-counter prohormones ("andro" products). Since then, most have been banned in the US (Anabolic Steroid Control Act of 2004) and are prohibited in competitive sport. Its own conclusions still stand: gains were modest at best, beginners have no reason to use them, and proper training and diet matter far more.

See also

• 6 Scientifically Proven Things Men Can Do To Be More Attractive
• Cardio and Muscle Growth
• Women Lack Self Control (physique as motivation)
• 7 step guide to getting started

Summary of a Bodybuilding.com article on testosterone (c. 2000), updated for current law.