Low energy availability in exercising men is associated with reduced leptin and insulin but not with changes in other metabolic hormones

Authors

Karsten Koehler, University of Nebraska-LincolnFollow
Neele R. Hoerner, German Sport University, Cologne
Jenna C. Gibbs, Pennsylvania State UniversityFollow
Christoph Zinner, University of WürzburgFollow
Hans Braun, German Sport University CologneFollow
Mary Jane De Souza, The Pennsylvania State UniversityFollow
Wilhelm Schaenzer, German Sport University CologneFollow

Document Type

Article

Date of this Version

2016

Citation

Published in Journal of Sports Sciences, 34:20 (2016), pp 1921-1929. doi:10.1080/02640414.2016.1142109

Comments

Copyright © 2016 Taylor & Francis. Used by permission.

Abstract

Low energy availability, defined as low caloric intake relative to exercise energy expenditure, has been linked to endocrine alterations frequently observed in chronically energy-deficient exercising women. Our goal was to determine the endocrine effects of low energy availability in exercising men. Six exercising men (V_O2peak : 49.3 ± 2.4 ml · kg⁻¹ · min⁻¹) underwent two conditions of low energy availability (15 kcal · kg⁻¹ fat-free mass [FFM] · day⁻¹) and two energy-balanced conditions (40 kcal · kg⁻¹ FFM · day⁻¹) in randomized order. During one low energy availability and one balanced condition, participants exercised to expend 15 kcal · kg⁻¹ FFM · day⁻¹; no exercise was conducted during the other two conditions. Metabolic hormones were assessed before and after each 4-day period. Following both low energy availability conditions, leptin (−53% to −56%) and insulin (−34% to −38%) were reduced (P < 0.05). Reductions in leptin and insulin were independent of whether low energy availability was attained with or without exercise (P > 0.80). Low energy availability did not significantly impact ghrelin, triiodothyronine, testosterone and IGF-1 (all P > 0.05). The observed reductions in leptin and insulin were in the same magnitude as changes previously reported in sedentary women. Further research is needed to understand why other metabolic hormones are more robust against low energy availability in exercising men than those in sedentary and exercising women.