Testosterone esters in oil are slowly absorbed from injection sites and then the ester groups are removed. So you have a time release bio-identical testosterone delivery system. Many docs like to mislead guys about this or they are simply stupid.
Any increase in your T levels will tend to shut down your own production. You can't take a little bit to increase T levels, you need to replace all production.
Please read these stickies - which do not have icons:
- advice for new guys --- covers basics that you need to know
- things that damage your hormones
- protocol for injections
- finding a TRT doc
Further reading: https://tnation.T-Nation.com/free_online_forum/sports_training_performance_bodybuilding_trt/hormones_and_health