Testosterone is responsible for promoting health and well-being through enhanced libido, energy, immunity, increased fat loss, gaining and maintaining lean muscle mass, preventing Osteoporosis (loss of bone density) and possible protection against heart disease. Testosterone is also responsible for normal growth and development of male sex organs and maintenance of secondary sex characteristics. Secondary sex characteristics are specific traits that separate the two sexes, but are not directly part of the reproductive system, for example: chest and facial hair, a distinguished jaw line, broad shoulders and increased muscle mass. Testosterone binds to the Androgen Receptors (AR), which thus causes accelerated muscle gain, fat loss, and muscle repair and growth. These mechanisms are stimulated by activation of the Androgen Receptors (either directly or indirectly as DHT).There are many possible side-effects associated with Testosterone Propionate use. This product has a high level of aromatization into estrogen and coverts to DHT (dihydrotestosterone) as well. Testosterone can convert to estrogen, the female sex hormone, creating a high risk of gynecomastia (formation of breast tissue in males). Also, supplementing Testosterone to your body will result in the shutting down of the body’s natural production of the hormone. The severity of side effects depend mostly on the dose and duration of circulating free testosterone and it’s conversion to estrogen and DHT. Testosterone’s anabolic/androgenic effects are dependant upon also dosage; the higher the dose the higher the muscle building effect.