Metabolic inflexibility is an early marker of bed-rest induced glucose intolerance even when fat mass is stable.

Metabolic inflexibility is an early marker of bed-rest induced glucose intolerance even when fat mass is stable.

J Clin Endocrinol Metab. 2018 Mar 12;:

Authors: Rudwill F, O'Gorman D, Lefai E, Chery I, Zahariev A, Normand S, Pagano AF, Chopard A, Damiot A, Laurens C, Hodson L, Canet-Soulas E, Heer M, Frings Meuthen P, Buehlmeier J, Baecker N, Meiller L, Gauquelin-Koch G, Blanc S, Simon C, Bergouignan A

Abstract
Context: The effects of energy balanced bed-rest on metabolic flexibility has not been thoroughly examined.
Objective: We investigated the effects of 21-days bed-rest, with and without whey protein supplementation, on metabolic flexibility while maintaining energy balance. We further hypothesized protein supplementation mitigates metabolic inflexibility by preventing muscle atrophy.
Design & Setting: Randomized cross-over longitudinal study conducted at the German Aerospace Center, Cologne, Germany.
Participants & Interventions: Ten healthy men were randomly assigned to dietary countermeasure or isocaloric control diet during a 21-day bed-rest.
Outcome Measures: Before and at the end of the bed-rest, metabolic flexibility was assessed during a meal test. Secondary outcomes were glucose tolerance by OGTT, body composition by DEXA, ectopic fat storage by MRI, and inflammation and oxidative stress markers.
Results: Bed-rest decreased the ability to switch from fat to carbohydrate oxidation when transitioning from fasted to fed states (i.e. metabolic inflexibility), anti-oxidant capacity, fat-free mass, and muscle insulin sensitivity along with greater fat deposition in muscle (p<0.05 for all). Changes in fasting insulin and inflammation were not observed. However, glucose tolerance was reduced during acute overfeeding. Protein supplementation did not prevent fat-free mass loss and metabolic alterations.
Conclusions: Physical inactivity triggers metabolic inflexibility, even when energy balance is maintained. While reduced insulin sensitivity and increased fat deposition were observed at the muscle level, systemic glucose intolerance was only detected in response to a moderately high-fat meal. This supports the role of physical inactivity in metabolic inflexibility, and further suggests that metabolic inflexibility precedes systemic glucose intolerance.

PMID: 29546280 [PubMed - as supplied by publisher]

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