Like any other anabolic steroid, using a supplement like Anavar will suppress natural production of testosterone. Be aware that Anavar is one of the mildest supplements for reducing testosterone production. Exogenous testosterone as a part of your supplement plan can help keep your natural testosterone production on track. If you do not do this, then you can have low testosterone , resulting in things like fatigue, lethargy, decreased muscle mass, and more. Some of this will require you figuring out what works for you. Since each and every physiology is so different, there may be a trial period where you work out any testosterone issues with your doctor. Be aware that once all artificial testosterone put into your body by you is gone, natural testosterone levels will resume as normal. Also be aware that you can damage the natural production of testosterone in your body by overdosing on anabolic steroids. It is often suggested that you should include a SERM and HCG with a PCT for best results.