Constitutional ThinnessLeanErgyNCT07233109
Energy Expenditure and Neuromuscular Function in Young Adult Women With a Naturally Thin Build (LeanErgy)
A study testing Evaluation of the maximum oxidation point of lipids, Evaluation of the energy cost of walking and Neuro-muscular assessments in people with Constitutional Thinness, run by Centre Hospitalier Emile Roux at 1 site in France.
Trial summary
People with a low BMI (<17.5) are most often considered to have anorexia nervosa (AN). However, recent literature suggests that there is a category of individuals with the same low BMI who do not meet the diagnostic criteria for anorexia nervosa but who have specific differences that make them a separate entity… Read more about this study
- Who is it for?
- Ages 18 to 35 years, women only
- Conditions the study is for
- Constitutional Thinness
- What is being tested?
- Evaluation of the maximum oxidation point of lipids, Evaluation of the energy cost of walking and Neuro-muscular assessments
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 36 participants
- Where
- 1 siteFrance
- Study dates
- 15 Dec 2025to 15 Feb 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- Women only
- No healthy volunteers
- Adult
Who may be able to join
- BMI ≤ 17.5 kg/m2
- 20 kg/m2 ≤ BMI ≤ 25 kg/m2
Who cannot join
- For women with Constitutional thinness :
- Women under guardianship or deprived of their liberty by judicial or administrative decision
- Women who are pregnant, breastfeeding, or likely to become pregnant
- Women who engage in intense physical activity (more than 3 sessions of physical activity per week)
- Abnormal levels of IGF-1, estradiol, free T3, cortisol, and leptin
- For the MC group specifically: cases of thinness due to a suspected organic cause. This includes Marfan syndrome, identifiable by: personal or family history of degenerative aortic disease (aneurysm, dissection), ligamentous hyperlaxity, arachnodactyly
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- History or presence of a systemic condition likely to interfere with the physiological and metabolic parameters measured (e.g., diabetes, endocrine or metabolic disease)
- Any acute or chronic disease that may influence the results (e.g., infections, tumors, inflammatory diseases)
- Medical or surgical history deemed by the investigator to be incompatible with this study (e.g., muscular, neurological, or joint disorders, or contraindications to the application of a magnetic field, etc.) Presence of diabetes, and any other condition limiting the application of either strategy under trial
- Use of medications that may interfere with the study results
- Cardiovascular conditions (history of cardiovascular and/or neurovascular disease, as well as the presence of cardiovascular and/or neurovascular risk factors other than obesity/overweight, such as: high blood pressure, high cholesterol, diabetes, heart rhythm disorder, known carotid atherosclerosis, thrombophilia)
- Surgery within the previous 3 months
- Women excluded from another study
- Regular tobacco or alcohol consumption
- Specific diets likely to impact metabolism, influence biological parameters (FT3, cortisol in particular) or skew results (deficiencies, low calorie intake). This includes vegan, mono, ketogenic, and low-calorie diets, intermittent fasting, or diets requiring specific supplementation that may interfere with the endocrine system.
- For women Normal-Weighted Women
- Women under guardianship or deprived of their liberty by judicial or administrative decision
- Women who are pregnant, breastfeeding, or likely to become pregnant.
- Women who engage in intense physical activity (more than 3 sessions of physical activity per week)
- History or presence of a systemic condition likely to interfere with the physiological and metabolic parameters measured (e.g., diabetes, endocrine or metabolic disorders)
- Any acute or chronic disease that may influence the results (e.g., infections, tumors, inflammatory diseases)
- Medical or surgical history deemed by the investigator to be incompatible with this study (e.g., muscular, neurological, or joint disorders, or contraindications to the application of a magnetic field, etc.)
- Presence of diabetes or any other condition limiting the application of either strategy under investigation
- Taking medications that may interfere with the study results
- Cardiovascular conditions (history of cardiovascular and/or neurovascular disease, as well as the presence of cardiovascular and/or neurovascular risk factors other than obesity/overweight, such as: high blood pressure, high cholesterol, diabetes, heart rhythm disorder, known carotid atherosclerosis, thrombophilia)
- Surgery within the previous 3 months
- Women excluded from another study
- Regular tobacco or alcohol consumption
- Specific diets likely to impact metabolism, influence biological parameters, or skew results (deficiencies, low calorie intake). This includes vegan, mono, ketogenic, and low-calorie diets, intermittent fasting, or diets requiring specific supplementation that may interfere with the endocrine system.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
France1 site
Laboratoire AME2P, Université Clermont Auvergne
Aubière, 63170
David Thivel, +00334 73 40 76 79, David.thivel@uca.fr
About this study
People with a low BMI (<17.5) are most often considered to have anorexia nervosa (AN). However, recent literature suggests that there is a category of individuals with the same low BMI who do not meet the diagnostic criteria for anorexia nervosa but who have specific differences that make them a separate entity: constitutional thinness (CM). Constitutional thinness differs from anorexia nervosa in several ways. First, unlike AN, CM individuals do not have eating disorders and express a strong desire to gain weight. Another difference concerns the menstrual cycle: without oral contraception, AN individuals experience amenorrhea, while CM individuals have regular menstrual cycles. Biological signs of malnutrition are also present in anorexia nervosa, whereas this is not the case in constitutional thinness. Indeed, concentrations of IGF1, free T3, and leptin are significantly reduced in AN compared to healthy subjects, whereas there is no significant difference between healthy subjects and CT. Finally, in terms of body composition, there is a significant difference in particular in the percentage of fat mass between MC and AM subjects, with the MC group having a significantly lower percentage of fat mass than the control subjects but significantly higher than the AM subjects. The clinical management of MC patients could involve nutritional management of patients but also management in the form of an Adapted Physical Activity intervention program. However, this type of program using physical activity and a nutritional approach must be based on a characterization of the energy profile and physical abilities of MC patients, which remains to be studied. Germain et al. proposed measuring the physical activity level of MC patients using Actiheart (a combination of heart rate and accelerometer) and compared it with that of normal-weight (NW) individuals, finding no difference between the groups. However, this analysis remains a secondary analysis of their study, as the statistical power and choice of tool are certainly not appropriate for this question. Our team recently conducted the Nutrilean project, which for the first time questioned the aerobic and muscular capacities of women with CM compared to their NP counterparts. While our results show lower force production capacity in CM patients, suggesting neuromuscular adaptations to the chronic mechanical unloading caused by CM rather than an impairment of contractile abilities themselves, this remains to be explored more specifically. Indeed, these differences disappeared after normalization to body weight or muscle mass, suggesting a reduced gross force production capacity, but probably reflecting a normal physiological adaptation to low body and muscle mass. It now appears necessary to carry out more specific neuromuscular analyses in order to better understand the mechanisms, adaptations, and/or potential neuromuscular dysfunctions in this population. Similarly, while the results do not appear to show any impairment in the aerobic capacity of CM, they do highlight a potential impairment in their energy efficiency during locomotion, which may also reflect an adaptation to chronic exposure to lower mechanical loads.
In this context and following on from the work carried out to date by our team, the main objective of this study is i) to compare the lipid oxidation capacity and energy cost of walking between MC and NP participants; ii) to explore the adaptations of this energy cost in MC women in response to mechanical overload.
- Conditions
- Constitutional Thinness
- Being tested
- Evaluation of the maximum oxidation point of lipids, Evaluation of the energy cost of walking, Neuro-muscular assessments
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Evaluation of the maximum oxidation point of lipidsDiagnostic test
The Lipoxmax measurement will take place in the morning, on an empty stomach. It will consist of a submaximal incremental exercise comprising five stages of six minutes each, with loads determined based on the power output obtained during the maximum oxygen consumption test and corresponding to 25%, 35%, 45%, 55%, and 65% of theoretical VO2 max. During the last minute of each stage, continuous measurement of VO2 and VCO2 will be used to calculate the average QR and then calculate the respective oxidation rates of carbohydrates and lipids, followed by the lipid oxidation rate at each stage. The oxidation rate curve is parabolic in shape, and modeling this curve will determine the lipoxmax point and the percentage of VO2max at which this lipoxmax point is obtained.
Evaluation of the energy cost of walkingDiagnostic test
The energy cost of walking for participants will be assessed once for the NP group and twice and randomized for the MC group. All participants will have their energy cost assessed based on their body weight, and so will be in the MC group with a mechanical overload applied to simulate a BMI of 20 kg/m² (normal weight). This overload will be simulated with a weight corresponding to the weight required to achieve this BMI.
Energy expenditure and energy substrates will be assessed during the walking exercise using portable indirect calorimetry (MetaMax, Inc.).This one is of the classic methods for measuring resting energy expenditure. For this exercise, participants will have to remain seated at rest for 10 minutes and then standing at rest for 5 minutes before performing an incremental submaximal walking exercise on a treadmill, consisting of 5 stages of 6 minutes each: i) 0.75 m.s-1; ii) 1 m.s-1; iii) 1.25 m.s-1; ii) 1.5 m.s-1; iv) 2.25 m.s-1. Each stage will be separated by 5 min.
Neuro-muscular assessmentsDiagnostic test
Neuromuscular function will be assessed using isokinetic dynamometry. Neuromuscular function of the lower limb (knee flexion/extension) Neuromuscular function of the upper limb (elbow flexion/extension)
| Study group | Role | What they receive |
|---|---|---|
| Woman with constitutional thinness | Experimental | Women aged between 18 and 35 Signed consent form Member of or entitled to social security Body Mass Index ≤ 17.5 kg/m2 Stable weight (no variation of more than 2kg over the last 12 months) No eating disorders No signs of malnutrition according to blood tests for cortisol* and FT3* No secondary amenorrhea Receives: Diagnostic Test: Evaluation of the maximum oxidation point of lipids; Diagnostic Test: Evaluation of the energy cost of walking; Diagnostic Test: Neuro-muscular assessments |
| Normal-weight women | Experimental | Women aged between 18 and 35 Signed consent form Member of or entitled to social security Body Mass Index between 20 kg/m² and 25 kg/m² Stable weight (No variation of more than 2 kg over the last 12 months) No eating disorders No secondary amenorrhea Receives: Diagnostic Test: Evaluation of the maximum oxidation point of lipids; Diagnostic Test: Evaluation of the energy cost of walking; Diagnostic Test: Neuro-muscular assessments |
What is being measured
The primary outcome is the main question the study is designed to answer.
Energy cost
Indirect calorimetry (measurement of gas exchange)
Measured: 4 months
Secondary outcomes (3)
Maximum lipid oxidation point
Indirect calorimetry (measurement of gas exchange)
Measured: 4 months
Perception of effort
Borg Scale (0: zero effort -10 maximum effort)
Measured: 4 months
Isometric and dynamic strength
Measurement on an isokinetic dynamometer
Measured: 4 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Nov 2025
- Study start15 Dec 2025 (estimated)
- Primary completion15 Oct 2027 (estimated)
- Study completion15 Feb 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Constitutional ThinnessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 36 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Centre Hospitalier Emile Roux
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07233109
- Sponsor's protocol ID
- RIPH2_GADEA_LeanErgy
- Other IDs
- 2025-A01848-41
- Acronym
- LeanErgy
- Status last verified
- Nov 2025
- First submitted
- 14 Nov 2025
- Last updated
- 18 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 18 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Energy Expenditure and Neuromuscular Function in Young Adult Women With a Naturally Thin Build (LeanErgy)
- ClinicalTrials.gov ID
- NCT07233109
- Acronym / sponsor ID
- LeanErgy / RIPH2_GADEA_LeanErgy
- Conditions
- Constitutional Thinness
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 36 participants (estimated)
- Lead sponsor
- Centre Hospitalier Emile RouxUniversity, hospital or other
- Study start
- 15 Dec 2025 (estimated)
- Primary completion
- 15 Oct 2027 (estimated)
- Study completion
- 15 Feb 2028 (estimated)
- First posted
- 18 Nov 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
People with a low BMI (<17.5) are most often considered to have anorexia nervosa (AN). However, recent literature suggests that there is a category of individuals with the same low BMI who do not meet the diagnostic criteria for anorexia nervosa but who have specific differences that make them a separate entity: constitutional thinness (CM). Constitutional thinness differs from anorexia nervosa in several ways. First, unlike AN, CM individuals do not have eating disorders and express a strong desire to gain weight. Another difference concerns the menstrual cycle: without oral contraception, AN individuals experience amenorrhea, while CM individuals have regular menstrual cycles. Biological signs of malnutrition are also present in anorexia nervosa, whereas this is not the case in constitutional thinness. Indeed, concentrations of IGF1, free T3, and leptin are significantly reduced in AN compared to healthy subjects, whereas there is no significant difference between healthy subjects and CT. Finally, in terms of body composition, there is a significant difference in particular in the percentage of fat mass between MC and AM subjects, with the MC group having a significantly lower percentage of fat mass than the control subjects but significantly higher than the AM subjects. The clinical management of MC patients could involve nutritional management of patients but also management in the form of an Adapted Physical Activity intervention program. However, this type of program using physical activity and a nutritional approach must be based on a characterization of the energy profile and physical abilities of MC patients, which remains to be studied. Germain et al. proposed measuring the physical activity level of MC patients using Actiheart (a combination of heart rate and accelerometer) and compared it with that of normal-weight (NW) individuals, finding no difference between the groups. However, this analysis remains a secondary analysis of their study, as the statistical power and choice of tool are certainly not appropriate for this question. Our team recently conducted the Nutrilean project, which for the first time questioned the aerobic and muscular capacities of women with CM compared to their NP counterparts. While our results show lower force production capacity in CM patients, suggesting neuromuscular adaptations to the chronic mechanical unloading caused by CM rather than an impairment of contractile abilities themselves, this remains to be explored more specifically. Indeed, these differences disappeared after normalization to body weight or muscle mass, suggesting a reduced gross force production capacity, but probably reflecting a normal physiological adaptation to low body and muscle mass. It now appears necessary to carry out more specific neuromuscular analyses in order to better understand the mechanisms, adaptations, and/or potential neuromuscular dysfunctions in this population. Similarly, while the results do not appear to show any impairment in the aerobic capacity of CM, they do highlight a potential impairment in their energy efficiency during locomotion, which may also reflect an adaptation to chronic exposure to lower mechanical loads.
In this context and following on from the work carried out to date by our team, the main objective of this study is i) to compare the lipid oxidation capacity and energy cost of walking between MC and NP participants; ii) to explore the adaptations of this energy cost in MC women in response to mechanical overload.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Woman with constitutional thinness | Experimental | Diagnostic Test: Evaluation of the maximum oxidation point of lipids, Diagnostic Test: Evaluation of the energy cost of walking, Diagnostic Test: Neuro-muscular assessmentsWomen aged between 18 and 35 Signed consent form Member of or entitled to social security Body Mass Index ≤ 17.5 kg/m2 Stable weight (no variation of more than 2kg over the last 12 months) No eating disorders No signs of malnutrition according to blood tests for cortisol* and FT3* No secondary amenorrhea |
| Normal-weight women | Experimental | Diagnostic Test: Evaluation of the maximum oxidation point of lipids, Diagnostic Test: Evaluation of the energy cost of walking, Diagnostic Test: Neuro-muscular assessmentsWomen aged between 18 and 35 Signed consent form Member of or entitled to social security Body Mass Index between 20 kg/m² and 25 kg/m² Stable weight (No variation of more than 2 kg over the last 12 months) No eating disorders No secondary amenorrhea |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- BMI ≤ 17.5 kg/m2
- 20 kg/m2 ≤ BMI ≤ 25 kg/m2
Key exclusion criteria (29 listed)
- For women with Constitutional thinness :
- For women Normal-Weighted Women
- Women under guardianship or deprived of their liberty by judicial or administrative decision
- Women who are pregnant, breastfeeding, or likely to become pregnant.
- Women who engage in intense physical activity (more than 3 sessions of physical activity per week)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Evaluation of the maximum oxidation point of lipidsThe Lipoxmax measurement will take place in the morning, on an empty stomach. It will consist of a submaximal incremental exercise comprising five stages of six minutes each, with loads determined based on the power output obtained during the maximum oxygen consumption test and corresponding to 25%, 35%, 45%, 55%, and 65% of theoretical VO2 max. During the last minute of each stage, continuous measurement of VO2 and VCO2 will be used to calculate the average QR and then calculate the respective oxidation rates of carbohydrates and lipids, followed by the lipid oxidation rate at each stage. The oxidation rate curve is parabolic in shape, and modeling this curve will determine the lipoxmax point and the percentage of VO2max at which this lipoxmax point is obtained. | Diagnostic test | Normal-weight women, Woman with constitutional thinness |
| Evaluation of the energy cost of walkingThe energy cost of walking for participants will be assessed once for the NP group and twice and randomized for the MC group. All participants will have their energy cost assessed based on their body weight, and so will be in the MC group with a mechanical overload applied to simulate a BMI of 20 kg/m² (normal weight). This overload will be simulated with a weight corresponding to the weight required to achieve this BMI. Energy expenditure and energy substrates will be assessed during the walking exercise using portable indirect calorimetry (MetaMax, Inc.).This one is of the classic methods for measuring resting energy expenditure. For this exercise, participants will have to remain seated at rest for 10 minutes and then standing at rest for 5 minutes before performing an incremental submaximal walking exercise on a treadmill, consisting of 5 stages of 6 minutes each: i) 0.75 m.s-1; ii) 1 m.s-1; iii) 1.25 m.s-1; ii) 1.5 m.s-1; iv) 2.25 m.s-1. Each stage will be separated by 5 min. | Diagnostic test | Normal-weight women, Woman with constitutional thinness |
| Neuro-muscular assessmentsNeuromuscular function will be assessed using isokinetic dynamometry. Neuromuscular function of the lower limb (knee flexion/extension) Neuromuscular function of the upper limb (elbow flexion/extension) | Diagnostic test | Normal-weight women, Woman with constitutional thinness |
Primary outcome
Energy cost
Time frame: 4 months
Indirect calorimetry (measurement of gas exchange)
3 secondary outcomes
Maximum lipid oxidation point
Time frame: 4 months
Perception of effort
Time frame: 4 months
Isometric and dynamic strength
Time frame: 4 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Nov 2025.
- Individual participant dataSharing planned: Undecided
Related trials for Constitutional Thinness
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Evaluation of the maximum oxidation point of lipids, Evaluation of the energy cost of walking and Neuro-muscular assessments in people with Constitutional Thinness, run by Centre Hospitalier Emile Roux at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 29 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 18 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact David THIVEL, Director of AME2P Laboratory (+0033 4 73 40 76 79, David.thivel@uca.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Energy cost (time frame: 4 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Nov 2025.