NCT07499167

Brief Summary

The goal of this single arm, interventional monocentric clinical trial is to investigate the physiological effects of a combination of head-down bedrest and caloric restriction on the human body. A set of measurements will assess the changes in the musculoskeletal, cardiovascular, hematological, immune, neurological, cognitive and metabolic systems, in 10 healthy male volunteers. The main question it aims to answer is: what are the physiological responses to fasting in a microgravity environment? In an exploratory study such as this one, where many physiological systems are explored, it is difficult to select a single important endpoint. However, given the known effect of both caloric restriction and head-down bedrest on muscle loss, and its critical importance for the success of space missions, lean body mass, as assessed by DEXA, was chosen as the primary endpoint. The secondary endpoints are:

  • Cardiovascular, muscular, neuro-vestibular and neuropsychological functional performance
  • The onset of clinical symptoms and biological changes Participants will be exposed to a microgravity analog model (head down bed rest) and controled caloric restriction environment for 10 days, multiple physiological assessments will be performed during this period. Followed by a rehab period before leaving the study.

Trial Health

77
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
10

participants targeted

Target at below P25 for not_applicable

Timeline
17mo left

Started Mar 2026

Geographic Reach
1 country

1 active site

Status
recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Progress11%
Mar 2026Sep 2027

First Submitted

Initial submission to the registry

February 27, 2026

Completed
11 days until next milestone

Study Start

First participant enrolled

March 10, 2026

Completed
20 days until next milestone

First Posted

Study publicly available on registry

March 30, 2026

Completed
6 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

September 21, 2026

Expected
1 year until next milestone

Study Completion

Last participant's last visit for all outcomes

September 21, 2027

Last Updated

March 30, 2026

Status Verified

March 1, 2026

Enrollment Period

7 months

First QC Date

February 27, 2026

Last Update Submit

March 23, 2026

Conditions

MicrogravityCaloric Restriction

Keywords

MicrogravityCaloric restriction

Outcome Measures

Primary Outcomes (1)

  • Lean Body Mass

    Lean Body Mass assessed by dual energy x-ray absorptiometry (DEXA)

    At baseline, during the ten days of intervention and until 90 days after the end of the intervention

Secondary Outcomes (36)

  • Change in body fluid compartments by bioelectrical impedance analysis

    At baseline, during the ten days of intervention and until 90 days after the end of the intervention

  • Change in whole-body Magnetic Resonance Imaging (MRI)

    At baseline and at day 9 of intervention period

  • Change in mood

    At baseline, during the ten days of intervention and until 4 days after the end of the intervention

  • Assessment of movements by volunteers

    At baseline, during the ten days of the intervention and until 4 days after the end of the intervention

  • Change in cardiovascular deconditioning and orthostatic tolerance (stand test)

    At baseline and 1 day after the end of intervention period

  • +31 more secondary outcomes

Study Arms (1)

Caloric restriction

EXPERIMENTAL

head down bedrest and caloric restriction (250 kcal/day)

Other: head down bedrest and caloric restriction

Interventions

head down bedrest and caloric restrictionOTHER

the intervention is 10 days of head down bedrest (-6°) and controlled and progressive caloric restriction, then controlled and progressive refeeding

Caloric restriction

Eligibility Criteria

Age20 Years - 40 Years
Sexmale(Gender-based eligibility)
Gender Eligibility Detailsbiological males
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • Healthy male volunteers (see below the description of medical tests and laboratory analysis performed at the selection visit)
  • Certified as healthy by a comprehensive clinical assessment (detailed medical history and complete physical examination): in particular, free from any known chronic disease or any acute mood or eating disorder, infectious disease or cardiovascular, metabolic, neurological, ENT (especially orthostatic hypotension and vestibular disorders), orthopedic or musculoskeletal disorders.
  • to 40 years old
  • to 185 cm
  • Body Mass Index between 20 and 26 kg.m-2
  • Stable body weight in the past 3 months (less than 4% change)
  • Fat Mass Index (FMI), defined as (bodyfat weigh in kg)/(height in m)2: between 3 and 6 kg.m-2, measured by whole-body DEXA
  • Triglyceride level under 1.7 mmol.L-1
  • Normal bone mass density at left hip and lumbar spine: T-score\>-1.5, measured by DEXA
  • VO2peak/VO2max between 35 and 55 mL.min-1.kg-1
  • Non-smokers
  • No alcohol or drug dependence, no medical treatment on a regular basis
  • Affiliated to a Social Security system and, for non-French resident, holding a European Health Insurance Card (EHIC) or a Global Health Insurance Card (GHIC).
  • Free of any engagement during the study
  • Who agreed to take part in the study and signed the informed consent

You may not qualify if:

  • Any history or presence of clinically relevant chronic disease; any acute infectious disease. Particularly (but not limited to):
  • Symptomatic orthostatic hypotension whatever the decrease in blood pressure, or asymptomatic postural hypotension defined by a decrease in SBP equal to or greater than 20 mmHg within 3 minutes when changing from the supine to the standing position
  • Personal or family history of thrombosis, genetic mutation for factor V or prothrombin gene
  • Cardiac arrhythmia
  • Hypertension
  • Auto-immune diseases or Raynaud's syndrome
  • History or symptoms of sleep apnea
  • Chronic back pains,
  • Vertebral fracture, scoliosis, or herniated disc,
  • Color-blindness,
  • Self-reported hearing problems or binocular visual acuity under 6/10 after correction
  • Vestibular disorders
  • Drug addiction
  • History of migraines,
  • History of hiatus hernia or gastro-esophageal reflux,
  • +25 more criteria

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Medes - Imps

Toulouse, Medes-imps, 31400, France

RECRUITING

MeSH Terms

Interventions

Caloric Restriction

Intervention Hierarchy (Ancestors)

Diet TherapyNutrition TherapyTherapeuticsEnergy IntakeDietNutritional Physiological PhenomenaDiet, Food, and NutritionPhysiological Phenomena

Central Study Contacts

Marie-Pierre Bareille

CONTACT

+33562174950marie-pierre.bareille@medes.fr

Study Design

Study Type
interventional
Phase
not applicable
Allocation
NA
Masking
NONE
Purpose
OTHER
Intervention Model
SINGLE GROUP
Sponsor Type
OTHER GOV
Responsible Party
SPONSOR

Study Record Dates

First Submitted

February 27, 2026

First Posted

March 30, 2026

Study Start

March 10, 2026

Primary Completion (Estimated)

September 21, 2026

Study Completion (Estimated)

September 21, 2027

Last Updated

March 30, 2026

Record last verified: 2026-03

Data Sharing

IPD Sharing
Will not share

Locations

FR(1)