An interventional study of Energy Deficit in Energy Supply; Deficiency, Severe, Energy Supply; Deficiency and Stress, Physiological, sponsored by United States Army Research Institute of Environmental Medicine. Completed at 1 site in United States. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-01-21.
Sponsored by United States Army Research Institute of Environmental Medicine · Not applicable, Interventional, and Basic science
This randomized, parallel study will examine the effects of energy balance and varying magnitudes of energy deficit on 1) the protein kinetic responses to consuming high quality protein and 2) carbohydrate oxidation during steady-state exercise. Healthy adults, representative of active duty military personnel, will complete a 2 d energy balance phase followed by a randomly assigned, 5 d energy deficit phase (n=15 per group; 20%, 40% and 60% energy deficit). At the end of each energy phase the effects of energy balance and energy deficit severity on resting postabsorptive (fasting) and postprandial (after consuming \~34 g protein) muscle protein synthesis (MPS) and whole-body protein synthesis, breakdown, and balance (synthesis - breakdown) will be determined. On the next day, the effects energy balance and energy deficit severity on carbohydrate oxidation during steady-state exercise will be determined. Primary study procedures include anthropometric and body composition measures, resting metabolic rate measures, aerobic exercise, tightly controlled diet and exercise interventions, repeated blood sampling, stable isotope infusion, stable isotope ingestion, and percutaneous muscle biopsies. The following hypotheses will be tested: 1) Δ (postprandial - postabsorptive) MPS and Δ whole-body protein balance at rest will progressively decrease as magnitude of energy deficit increases and 2) exogenous carbohydrate oxidation will be higher and endogenous carbohydrate oxidation will be lower during steady-state exercise as magnitude of energy deficit increases.
United States Army Research Institute of Environmental Medicine is the lead sponsor of 67 studies on the registry; 9 are open to participants now.
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Exclusion Criteria:
Energy Deficit equal to 20% total daily energy requirements.
Other: Energy Deficit
Energy Deficit equal to 40% total daily energy requirements.
Other: Energy Deficit
Energy Deficit equal to 60% total daily energy requirements.
Other: Energy Deficit
A combination of individualized exercise performed on a cycle ergometer and individualized dietary prescriptions will be used to achieve energy balance or the assigned energy deficits throughout the controlled feeding and testing periods
Whole-body protein balance
Determined using L-\[1-13C\]-leucine stable isotope.
Time frame: 2 days
Muscle Protein Synthesis
Determined using L-\[ring-2H5\]-phenylalanine stable isotope.
Time frame: 2 days
Carbohydrate Oxidation during Steady-state Exercise
Determined using U-13C-glucose stable isotope.
Time frame: 2 days
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United States Army Research Institute of Environmental Medicine