LGD-4033 is a selective androgen receptor modulator (SARM). LGD-4033 binds to the androgen receptor of muscle and bone selectively, exhibiting similar effects as testosterone, with only partial agonist activity on the prostate. It was developed as a way to treat diseases or conditions associated with muscle and bone deterioration. The advantage a SARM like LGD has over testosterone is the difference in activity it has on the body outside of muscle and bone.
LGD-4033as a significant effect on building lean muscle mass, strengthening bone and muscle, and it even has potential to help with healing. This is the most anabolic of SARMS, but, just like its cousins andarine and mk-2866, it binds very strongly to the androgen receptor. However, it favors the receptors in your muscle and bone, causing anabolic and anti-catabolic effects. In addition, it has a significant effect in preventing bone degeneration, and it has even proven to strengthen bones with minimized risk of typical androgenic problems like prostate enlargement, hair loss, etc.
In one study, male rats were castrated and left untreated for 14 days to allow for muscle and prostate to atrophy. These rats were then treated with LGD-4033 after 14 days and showed potent activity in the skeletal muscle, but very weak activity in the prostate despite higher concentrations being found there. Another study, conducted by Ligand over a 28 day period, showed that increased muscle mass in female rats was related to an increase in the muscle fibre cross sectional diameter due to LGD-4033 use.