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Responsiveness of the reproductive axis to a single missed evening meal in young adult males

Authors

  • Benjamin C. Trumble,

    Corresponding author
    1. Department of Anthropology, University of Washington, Seattle, Washington 98195
    2. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington 98195
    • Department of Anthropology and, The Center for Studies in Demography and Ecology, Box 353100, University of Washington, Seattle, Washington 98195, USA
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  • Eleanor Brindle,

    1. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington 98195
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  • Michalina Kupsik,

    1. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington 98195
    2. University of Washington School of Medicine, Seattle, Washington 98195
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  • Kathleen A. O'Connor

    1. Department of Anthropology, University of Washington, Seattle, Washington 98195
    2. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington 98195
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Abstract

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.

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