Elsevier

Metabolism

Volume 65, Issue 4, April 2016, Pages 416-427
Metabolism

Clinical Science
Altered metabolic homeostasis is associated with appetite regulation during and following 48-h of severe energy deprivation in adults,☆☆

https://doi.org/10.1016/j.metabol.2015.11.001Get rights and content
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Abstract

Background

Military personnel frequently endure intermittent periods of severe energy deficit which can compromise health and performance. Physiologic factors contributing to underconsumption, and the subsequent drive to overeat, are not fully characterized. This study aimed to identify associations between appetite, metabolic homeostasis and endocrine responses during and following severe, short-term energy deprivation.

Methods

Twenty-three young adults (17 M/6 F, 21 ± 3 years, BMI 25 ± 3 kg/m2) participated in a randomized, controlled, crossover trial. During separate 48-h periods, participants increased habitual energy expenditure by 1647 ± 345 kcal/d (mean ± SD) through prescribed exercise at 40–65% VO2peak, and consumed provided isovolumetric diets designed to maintain energy balance at the elevated energy expenditure (EB; 36 ± 93 kcal/d energy deficit) or to produce a severe energy deficit (ED; 3681 ± 716 kcal/d energy deficit). Appetite, markers of metabolic homeostasis and endocrine mediators of appetite and substrate availability were periodically measured. Ad libitum energy intake was measured over 36 h following both experimental periods.

Results

Appetite increased during ED and was greater than during EB despite maintenance of diet volume (P = 0.004). Ad libitum energy intake was 907 kcal/36 h [95% CI: 321, 1493 kcal/36 h, P = 0.004] higher following ED compared to following EB. Serum beta-hydroxybutyrate, free fatty acids, branched-chain amino acids, dehydroepiandrosterone-sulfate (DHEA-S) and cortisol concentrations were higher (P < 0.001 for all), whereas whole-body protein balance was more negative (P < 0.001), and serum glucose, insulin, and leptin concentrations were lower (P < 0.001 for all) during ED relative to during EB. Cortisol concentrations, but not any other hormone or metabolic substrate, were inversely associated with satiety during EB (R2 = 0.23, P = 0.04). In contrast, serum glucose and DHEA-S concentrations were inversely associated with satiety during ED (R2 = 0.68, P < 0.001). No associations between physiologic variables measured during EB and ad libitum energy intake following EB were observed. However, serum leptin and net protein balance measured during ED were inversely associated with ad libitum energy intake following ED (R2 = 0.48, P = 0.01).

Conclusion

These findings suggest that changes in metabolic homeostasis during energy deprivation modulate appetite independent of reductions in diet volume. Following energy deprivation, physiologic signals of adipose and lean tissue loss may drive restoration of energy balance. Clinical trials registration: www.clinicaltrials.gov #NCT01603550.

Abbreviations

BCAA
branched-chain amino acids
BHB
beta-hydroxybutyrate
DHEA-S
dehydroepiandrosterone-sulfate
EB
energy balance condition
ED
energy deprivation condition
FFA
free fatty acids
RMR
resting metabolic rate
SLIM
Satiety Labeled Intensity Magnitude scale
TDEE
total daily energy expenditure
TG
triglycerides

Keywords

Energy density
Satiety
Substrate oxidation
Weight loss
Starvation

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The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Army or the Department of Defense. Any citations of commercial organizations and trade names in this report do not constitute an official Department of the Army endorsement of approval of the products or services of these organizations.

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Clinical trials registration: clinicaltrials.gov #NCT01603550.