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Responsiveness of the reproductive axis to a single missed evening meal in young adult males
Author(s) -
Trumble Benjamin C.,
Brindle Eleanor,
Kupsik Michalina,
O'Connor Kathleen A.
Publication year - 2010
Publication title -
american journal of human biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.559
H-Index - 81
eISSN - 1520-6300
pISSN - 1042-0533
DOI - 10.1002/ajhb.21079
Subject(s) - morning , evening , testosterone (patch) , luteinizing hormone , endocrinology , medicine , urinary system , hormone , physiology , physics , astronomy
Objectives: The male reproductive axis is responsive to energetic deficits, including multiday fasts, but little is known about brief periods of fasting (<24 hours). Reduced testosterone in low‐energy balance situations is hypothesized to reflect redirection of resources from reproduction to survival. This study tests the hypothesis that testosterone levels decrease during a minor caloric deficiency by assessing the effects of a single missed (evening) meal on morning testosterone in 23 healthy male participants, age 19–36. Methods: Participants provided daily saliva and urine samples for two baseline days and the morning following an evening fast (water only after 4 PM). Testosterone, cortisol, and luteinizing hormone were measured with enzyme immunoassays. Results: Fasting specimens had significantly lower overnight urinary luteinizing hormone ( P = 0.045) and morning salivary testosterone than baseline ( P = 0.037). In contrast to morning salivary testosterone, there was a significant increase in overnight urinary testosterone ( P = 0.000) following the evening fast, suggesting an increase in urinary clearance rates. There was a marginal increase in overnight urinary cortisol ( P = 0.100), but not morning salivary cortisol ( P = 0.589). Conclusion: These results suggest the male reproductive axis may react more quickly to energetic imbalances than has been previously appreciated. Am. J. Hum. Biol., 2010. © 2010 Wiley‐Liss, Inc.