Testosterone levels peak during men's late 20's. As males increase in age, their ability to produce testosterone decreases thus resulting in low testosterone levels. Without normal levels of testosterone, men often experience a loss of libido and/or erectile dysfunction.
Some other internal signs of low testosterone may result in mood swings, inability to concentrate, reduced energy, depression and osteoporosis (a decrease in bone mineral density) as well as, lowered sperm count and fertility.
Outward signs of low testosterone include a decrease in body mass and strength due to a loss in muscle tissue and an increase in body fat. Also, men may experience a loss of body hair, breast enlargement can occur and male testes may become smaller and softer due to low testosterone levels.
