Influence of short-term fasting on the pituitary-testicular axis in normal men

Horm Res. 1987;25(3):140-6. doi: 10.1159/000180645.


To investigate whether short-term fasting affects serum testosterone (T) in normal subjects, 10 healthy men of normal weight were studied on two occasions: after an overnight fast (8 h), and after an additional 48 h of fasting. Blood glucose declined by 22 +/- 3% between the tests (p less than 0.001). Basal serum T fell from 8.7 +/- 0.7 to 5.7 +/- 0.8 micrograms/l (p less than 0.01), and LH from 6.9 +/- 0.8 to 5.0 +/- 0.7 U/l (p less than 0.01). Serum estradiol (E2) and FSH remained unaffected. To explore possible mechanisms behind the decreased basal release of T and LH, 9 small doses of glucose were given orally at regular intervals during a 56-hour fast to 9 additional normal men to maintain blood glucose levels. These men did not experience a fall in serum T or LH. Six additional normal men were given 50 micrograms GnRH intravenously after an overnight fast, and after a fasting period of 56 h. No acute increase in T was seen after the overnight fast, but after the 56-hour fast GnRH raised serum T by 55 +/- 14% (p less than 0.02). Moreover, fasting augmented the GnRH-induced LH response by 64 +/- 15% (p less than 0.02. These results imply that: short-term fasting exerts inhibitory influence on Leydig cell function via a mechanism which might involve a reduced hypothalamic and/or pituitary stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • Estradiol / blood
  • Fasting*
  • Follicle Stimulating Hormone / blood
  • Humans
  • Luteinizing Hormone / blood
  • Male
  • Pituitary Gland / metabolism*
  • Pituitary Hormone-Releasing Hormones / pharmacology
  • Testis / metabolism*
  • Testosterone / blood*
  • Time Factors


  • Blood Glucose
  • Pituitary Hormone-Releasing Hormones
  • Testosterone
  • Estradiol
  • Luteinizing Hormone
  • Follicle Stimulating Hormone