Effects of testosterone deficiency on body composition, strength and sexual function in men

July 2014

This paper presents the findings from a study that looked at the effects of testosterone on body fat, lean mass, thigh-muscle area and strength, and sexual function in healthy men who had their testosterone levels experimentally reduced. As the majority of estradiol (a form of estrogen) is obtained from testosterone, the concomitant decrease in estradiol was also investigated and the effects differentiated from those of testosterone.

Key findings

  • The dose of testosterone required to prevent adverse changes on body composition, strength and sexual function is variable, and treatment should be on an individual basis
  • Testosterone deficiency causes decreases in lean mass, thigh-muscle area and strength
  • Estradiol deficiency plays a role in the increase in body fat
  • Both testosterone and estradiol are needed for the maintenance of normal sexual function

Source: Gonadal steroids and body composition, strength, and sexual function in men. Finkelstein JS, Lee H, Burnett-Bowie S-A, et al. N Engl J Med 2013;369:1011–22.

Background information

Low testosterone levels are widely recognized to be associated with decreases in lean mass and strength, an increase in body fat and impaired sexual function, and testosterone treatment can reverse these changes. However, the effects of a decline in estrogen, which is produced from testosterone, also need to be considered as it plays an important role in bone metabolism and regulation of body fat and sexual function.