Free Testosterone

Testosterone is the primary androgenic hormone, mediating functions like libido, muscular development and strength, fat loss, energy levels, cognitive and digestive function. Testosterone production is positively influenced by sufficient calorie intake, dietary carbohydrate (due to insulin), vitamin D, zinc, vitamin A, resistance training and proper sleep, and can be impaired due to oxidative stress, hypothyroidism and inflammation. Most testosterone in the bloodstream is bound by carrier proteins. Free testosterone is the amount of testosterone that is not protein bound, biologically available to tissues to exert its effects.