anabolic steroid

Anabolic steroids are man-made cousins of testosterone, engineered to maximize muscle-building (anabolic) effects. People take them, often in doses far above anything the body makes, to gain muscle size and strength faster than training alone allows.

Chemically these are synthetic androgens that act on the same androgen receptor as natural testosterone, boosting protein synthesis in muscle. The catch lies in feedback: the brain senses the flood of androgen and shuts down its own GnRH, LH, and FSH. With LH and FSH switched off, the testes stop making their own testosterone and stop producing sperm, so the testes shrink and fertility falls, sometimes for many months after stopping.

Beyond suppressed fertility, supraphysiologic doses carry real harms: acne, hair loss, mood swings and aggression, and effects on the heart, liver, and cholesterol. A characteristic irony is that excess androgen is partly converted by aromatase into estrogen, which can cause gynecomastia in heavy users. Medically supervised testosterone for genuine deficiency is a different matter; the dangers here come from the high, unmonitored doses used for performance and appearance.