Letrozole reduces estrogen-related side effects: It prevents the conversion of androgens to estrogen, minimizing unwanted gynecomastia (male breast development), water retention, and belly fat. Letrozole Increases testosterone levels: By inhibiting the aromatase enzyme, letrozole can boost natural testosterone levels in men by preventing its breakdown. Post-cycle therapy (PCT): Some bodybuilders use letrozole as part of PCT to help normalize hormone levels after a cycle,