We know that men and women are different in so many weird and wonderful ways, however right at the beginning of an embryo's development, males and females are the same. Both have a pair of identical undifferentiated gonads, which have the potential to develop into testes or ovaries.
It has been identified as a single gene on the male Y chromosome that binds to the DNA of the gonads, causing them to become testes, and if the gene is not present ovaries will develop.
Following that choice, it is the hormones that organise everything through the internal and external sexual development, including the brain, in preparation for later activation in life, during puberty.
Testosterone is classified as a steroidal androgen and is the key male sex hormone that develops masculinisation, growth of facial hair, lowering the voice, fertility, and muscle and fat distribution. Pubic and underarm hair is produced by androgens from the adrenals, which both sexes produce. Both types of glands (testes and ovaries) produce a small amount of the hormone of the other sex.
Testosterone has two specific actions - androgenic (masculinising) and anabolic (tissue building). Testosterone alone will not build muscle, we also require adequate protein, essential fatty acids, vitamins and minerals. The muscle also must have work to develop and strengthen. A lean body mass helps control weight and will support energy pathways as it is more efficient at burning fuel.
The normal range of testosterone varies widely with individual biochemical differences. When in excess the fearlessness often seen in men, can turn to violence and aggression with paranoia type reactions.
Testosterone production is a substantial process with many metabolic pathways, starting with the hypothalamus and pituitary in the brain, via other hormones, to stimulate the testes into action.
Hormone production naturally slows down with age and testosterone supplementation is used for specific medical conditions.
Synthetic anabolic steroid use for growth of muscle in various sports usually ends sadly. Side effects can be huge including heart and liver damage, impotence and loss of libido.
All hormone health is reliant on good nutritional wellness. Nutrients such as zinc and vitamin C may not directly stimulate testosterone production, however vitamin C is essential for the structural support of testicular tissue, without which it could not function properly and zinc is required to maintain the task of the Leydig cells, where testosterone is produced, within the testes and is a major mineral for quality and motility of sperm.