LGD-4033 binds with high affinity to androgen receptors in muscle and bone tissue, acting much like testosterone in those tissues but without being a substrate for 5-alpha-reductase or aromatase. This means it doesn’t convert to DHT or estrogen. Upon binding to the androgen receptor, LGD-4033 upregulates the expression of genes that promote protein synthesis and muscle fiber growth. In clinical studies, even doses as low as 1 mg/day resulted in measurable increases in lean body mass within 3 weeks. LGD-4033 was initially created (by Ligand Pharmaceuticals, hence “Ligandrol”) to help patients with muscle wasting conditions – it builds muscle and strengthens bone without the androgenic side effects of steroids. It has a half-life of ~24–36 hours, allowing convenient once-daily dosing. Notably, LGD-4033 does cause some suppression of natural testosterone during use (because the body senses an external androgen signal), but studies showed it was well-tolerated and suppression was reversible. As a SARM, LGD-4033 offers a targeted anabolic effect: it may activate similar pathways to steroids in muscle but is tissue-selective, sparing other organs from excessive androgen stimulation. This selectivity translates to significant muscle and strength gains, improved bone density, and potential therapeutic use in osteoporosis or muscle-wasting illnesses.