Obesity and OverweightNCT06860776
How Metabolism Affects Weight Loss and Gain
An observational study of Obesity and Overweight, run by University Hospital Schleswig-Holstein at 1 site in Germany.
Trial summary
This study examines why some individuals with obesity have difficulty losing weight, whereas some lean individuals struggle to gain weight. The investigators will measure how the human body uses energy during a fasting period and after consumption of a specially designed, low-protein meal. Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity and Overweight
- How many people
- 20 participants
- Where
- 1 siteGermany
- Study dates
- 16 Sep 2024to 1 Mar 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
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 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Participants will be recruited from the general adult population, focusing on two specific groups: 1. Lean individuals (BMI 18.5-22.0 kg/m²) who struggle to gain weight 2. Individuals with obesity (BMI >30 kg/m²) who struggle to lose weight All participants must be generally healthy, between 18 and 70 years old, and report a stable body weight (less than 5% fluctuation) in the last six months. Recruitment will occur via community outreach, advertisements, and existing volunteer registries. Potential participants with conditions or circumstances that could affect appetite, energy expenditure, or study compliance will be excluded.
Who may be able to join
- Group 1 (Lean): BMI 18.5-22.0 kg/m², reporting difficulty gaining weight
- Group 2 (Obese): BMI >30 kg/m², reporting difficulty losing weight
- Healthy status as determined by medical history, physical examination, and laboratory tests
- Stable weight (less than 5% fluctuation) over the past 6 months
Who cannot join
- Prediabetes (HbA1c >5.6% or fasting blood glucose >100 mg/dL) or diabetes mellitus
- Conditions affecting appetite or energy expenditure (e.g., Cushing's syndrome, uncontrolled hyper-/hypothyroidism)
- Gastrointestinal disorders that impact nutrient absorption (e.g., inflammatory bowel disease, malabsorption syndromes, ulcers)
- Psychiatric conditions influencing eating behavior (e.g., active depression, anorexia nervosa, bulimia nervosa, borderline personality disorder)
- Acute, unstable cardiovascular disease requiring hospitalization within the last 6 months (e.g., stent placement)
- Cancer that required treatment in the past 5 years
Show all 16Show fewer
- Chronic kidney disease (Stage IV or higher, per NKF criteria)
- Active infectious disease (e.g., HIV, hepatitis)
- Current nicotine use or nicotine use within the last month prior to screening
- Illicit drug use (e.g., amphetamines, cocaine, heroin, marijuana)
- Regular high-intensity physical activity (≥1 hour/day)
- Non-MRI-compatible metallic implants (e.g., artificial joints, metal plates)
- Pregnancy or breastfeeding
- Use of weight-loss medications
- Clinically significant claustrophobia
- Any other condition not mentioned above that, in the opinion of the investigator, could interfere with study participation or compromise patient safety
Trial locations and contacts
1 site in 1 country.
Germany1 site
University Hospital Schleswig-Holstein
Kiel, Schleswig-Holstein, 24105
About this study
Official title: Pilot Study on the Analysis of the Metabolic Phenotype in Individuals With Difficulties in Losing and Gaining Weight
This study examines why some individuals with obesity have difficulty losing weight, whereas some lean individuals struggle to gain weight. The investigators will measure how the human body uses energy during a fasting period and after consumption of a specially designed, low-protein meal. By comparing these responses, the investigators aim to identify different "metabolic phenotypes" that affect weight control. Findings from this research may lead to more personalized treatments for managing weight. Participation in this study involves simple tests and basic body measurements.
Read the detailed description
This study aims to better understand why certain individuals find it difficult to lose weight while others struggle to gain weight. Investigators believe that differences in how the human body uses energy-referred to as the metabolic phenotype-may play a key role.
Two groups of participants will be compared: one group includes lean individuals who have difficulty gaining weight, and the other group consists of individuals with obesity who have difficulty losing weight. Participants will undergo a series of tests designed to measure how the human body burns calories under different conditions.
The study involves two main components:
- 24-Hour Fasting Period: Participants will abstain from eating for 24 hours to observe how the body adapts by either conserving or maintaining energy expenditure.
- Meal Test: Following the fasting period, participants will consume a specially designed, low-protein meal that simulates overeating. The investigators will measure how much additional energy is burned during digestion, a process known as diet-induced thermogenesis.
A technique called indirect calorimetry will record oxygen consumption and carbon dioxide production. These measurements help calculate resting energy expenditure (REE), which refers to the calories the body burns while at rest, and any changes that occur after fasting and eating.
The goal is to identify distinct metabolic patterns. Some individuals may have a "thrifty" metabolism that conserves energy, making weight loss more challenging, whereas others may have a "spendthrift" metabolism that expends more energy, potentially explaining difficulty in gaining weight. Understanding these differences could lead to more personalized and effective weight management strategies.
This study is conducted under strict safety and ethical standards to ensure minimal risk to participants. By examining the relationship between metabolism and weight control, the findings may pave the way for improved treatments for obesity and related weight issues.
- Conditions
- Obesity and Overweight
- Keywords
- obesity, metabolic phenotype, thrifty, spendthrift, diet-induced thermogenesis, fasting, indirect calorimetry
- Medical subject headings
- Obesity, Overweight, Fasting
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Lean individual with weight gain difficulties | Participants in this group are lean individuals (BMI 18.5-22.0 kg/m²) who have difficulty gaining weight. They will undergo a 24-hour fasting period followed by a controlled low-protein, high-calorie meal test. Researchers will measure their resting metabolic rate before and after fasting, as well as the body's response to the test meal. By comparing these results to those of other groups, the study aims to identify metabolic factors that influence weight gain difficulties and guide future personalized treatments. | |
| Individuals with obesity and weight loss difficulties | Participants in this group are individuals with obesity (BMI >30 kg/m²) who have difficulty losing weight. They will undergo a 24-hour fasting period followed by a controlled low-protein, high-calorie meal test. Researchers will measure their resting metabolic rate before and after fasting, as well as the body's response to the test meal. By comparing these findings with those of other groups, the study seeks to uncover metabolic factors that contribute to weight loss difficulties and guide more personalized treatment approaches. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Identification of Metabolic Phenotypes in Lean vs. Obese Individuals
We aim to determine whether individuals with obesity (BMI >30 kg/m²) exhibit a more "thrifty" metabolic phenotype (lower resting metabolic rate [RMR] after 24-hour fasting and reduced diet-induced thermogenesis [DIT]) compared to lean individuals (BMI 18.5-22 kg/m²) who have trouble gaining weight, hypothesized to show a more "spendthrift" metabolic phenotype (increased RMR after fasting and higher DIT). RMR is measured via indirect calorimetry before and after a 24-hour fast, followed by a high-calorie, low-protein meal test to assess DIT.
Measured: Measured at baseline (Day 1) and after 24-hour fasting (Day 2)
Secondary outcomes (6)
Correlation Between Fasting-Induced Energy Expenditure Changes and Diet-Induced Thermogenesis
Evaluate how the change in resting metabolic rate (RMR) after a 24-hour fast relates to diet-induced thermogenesis (DIT) following a high-calorie, low-protein meal. This will clarify the interaction between fasting adaptation and meal-related energy expenditure in lean vs. obese individuals.
Measured: Baseline (Day 1), post-fasting (Day 2), and after the meal test (Day 2)
Assessment of Metabolic Flexibility via Respiratory Quotient
Determine whether individuals with obesity show a smaller shift in their respiratory quotient (RQ) after fasting and the meal test, indicating lower metabolic flexibility compared to lean participants.
Measured: Baseline (Day 1), post-fasting (Day 2), and after the meal test (Day 2)
Correlation Between Weight Gain at 12-Month Follow-Up and Initial Metabolic Phenotype
Body weight (in kilograms) will be measured at baseline and again after 12 months using a calibrated scale. The correlation between weight change over this period and the initial metabolic phenotype (classified as "thrifty" or "spendthrift") will be assessed. The metabolic phenotype is determined by changes in resting metabolic rate (RMR) and diet-induced thermogenesis (DIT), both measured via indirect calorimetry.
Measured: 12-month follow-up
Correlation Between Weight Gain at 12-Month Follow-Up and Diet-Induced Thermogenesis
Body weight (in kilograms) will be measured at baseline and again after 12 months using a calibrated scale. The correlation between weight change over this period and the magnitude of diet-induced thermogenesis (DIT) will be assessed. DIT is determined via indirect calorimetry after a controlled, low-protein meal. This assessment will help identify whether higher or lower DIT predicts long-term weight change.
Measured: 12-month follow-up
Correlation Between Meal Test Diet-Induced Thermogenesis and Fibroblast Growth Factor 21 (FGF-21) Secretion
Fibroblast Growth Factor 21 (FGF-21) levels (in picograms per milliliter) will be measured in blood samples collected after the high-calorie, low-protein meal. The correlation between FGF-21 levels and diet-induced thermogenesis (DIT) will be assessed. DIT is measured using indirect calorimetry to quantify energy expenditure following the meal. This analysis will help determine whether FGF-21 may serve as a biomarker of metabolic adaptation.
Measured: After the meal test (Day 2)
Correlation Between Gut Hormones and Changes in Energy Expenditure
Serum levels of gut hormones (e.g., ghrelin, glucagon-like peptide-1 [GLP-1]) will be measured in picograms per milliliter. Resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) will be assessed via indirect calorimetry before and after a 24-hour fast, as well as after a high-calorie, low-protein meal. The correlation between gut hormone levels and changes in energy expenditure (RMR and DIT) will be evaluated to investigate hormonal influences on metabolic responses.
Measured: Baseline (Day 1), after 24-hour fast (Day 2), and after the meal test (Day 2)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Mar 2025
- Study start16 Sep 2024
- Primary completion1 Mar 2026
- Study completion1 Mar 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity and OverweightStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Hospital Schleswig-Holstein
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Tim Hollstein, University Hospital Schleswig-Holstein
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06860776
- Sponsor's protocol ID
- D 481/24
- Status last verified
- Jul 2026
- First submitted
- 28 Feb 2025
- Last updated
- 7 Jul 2026
- 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 7 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pilot Study on the Analysis of the Metabolic Phenotype in Individuals With Difficulties in Losing and Gaining Weight
- ClinicalTrials.gov ID
- NCT06860776
- Acronym / sponsor ID
- D 481/24
- Conditions
- Obesity and Overweight
- Keywords
- obesity, metabolic phenotype, thrifty, spendthrift, diet-induced thermogenesis, fasting, indirect calorimetry
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- University Hospital Schleswig-HolsteinUniversity, hospital or other
- Study start
- 16 Sep 2024 (actual)
- Primary completion
- 1 Mar 2026 (actual)
- Study completion
- 1 Mar 2026 (actual)
- First posted
- 6 Mar 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.
This study examines why some individuals with obesity have difficulty losing weight, whereas some lean individuals struggle to gain weight. The investigators will measure how the human body uses energy during a fasting period and after consumption of a specially designed, low-protein meal. By comparing these responses, the investigators aim to identify different "metabolic phenotypes" that affect weight control. Findings from this research may lead to more personalized treatments for managing weight. Participation in this study involves simple tests and basic body measurements.
Detailed description
This study aims to better understand why certain individuals find it difficult to lose weight while others struggle to gain weight. Investigators believe that differences in how the human body uses energy-referred to as the metabolic phenotype-may play a key role.
Two groups of participants will be compared: one group includes lean individuals who have difficulty gaining weight, and the other group consists of individuals with obesity who have difficulty losing weight. Participants will undergo a series of tests designed to measure how the human body burns calories under different conditions.
The study involves two main components:
- 24-Hour Fasting Period: Participants will abstain from eating for 24 hours to observe how the body adapts by either conserving or maintaining energy expenditure.
- Meal Test: Following the fasting period, participants will consume a specially designed, low-protein meal that simulates overeating. The investigators will measure how much additional energy is burned during digestion, a process known as diet-induced thermogenesis.
A technique called indirect calorimetry will record oxygen consumption and carbon dioxide production. These measurements help calculate resting energy expenditure (REE), which refers to the calories the body burns while at rest, and any changes that occur after fasting and eating.
The goal is to identify distinct metabolic patterns. Some individuals may have a "thrifty" metabolism that conserves energy, making weight loss more challenging, whereas others may have a "spendthrift" metabolism that expends more energy, potentially explaining difficulty in gaining weight. Understanding these differences could lead to more personalized and effective weight management strategies.
This study is conducted under strict safety and ethical standards to ensure minimal risk to participants. By examining the relationship between metabolism and weight control, the findings may pave the way for improved treatments for obesity and related weight issues.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Lean individual with weight gain difficulties | – | –Participants in this group are lean individuals (BMI 18.5-22.0 kg/m²) who have difficulty gaining weight. They will undergo a 24-hour fasting period followed by a controlled low-protein, high-calorie meal test. Researchers will measure their resting metabolic rate before and after fasting, as well as the body's response to the test meal. By comparing these results to those of other groups, the study aims to identify metabolic factors that influence weight gain difficulties and guide future personalized treatments. |
| Individuals with obesity and weight loss difficulties | – | –Participants in this group are individuals with obesity (BMI >30 kg/m²) who have difficulty losing weight. They will undergo a 24-hour fasting period followed by a controlled low-protein, high-calorie meal test. Researchers will measure their resting metabolic rate before and after fasting, as well as the body's response to the test meal. By comparing these findings with those of other groups, the study seeks to uncover metabolic factors that contribute to weight loss difficulties and guide more personalized treatment approaches. |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Participants will be recruited from the general adult population, focusing on two specific groups: 1. Lean individuals (BMI 18.5-22.0 kg/m²) who struggle to gain weight 2. Individuals with obesity (BMI >30 kg/m²) who struggle to lose weight All participants must be generally healthy, between 18 and 70 years old, and report a stable body weight (less than 5% fluctuation) in the last six months. Recruitment will occur via community outreach, advertisements, and existing volunteer registries. Potential participants with conditions or circumstances that could affect appetite, energy expenditure, or study compliance will be excluded.
Key inclusion criteria (4 listed)
- Group 1 (Lean): BMI 18.5-22.0 kg/m², reporting difficulty gaining weight
- Group 2 (Obese): BMI >30 kg/m², reporting difficulty losing weight
- Healthy status as determined by medical history, physical examination, and laboratory tests
- Stable weight (less than 5% fluctuation) over the past 6 months
Key exclusion criteria (16 listed)
- Prediabetes (HbA1c >5.6% or fasting blood glucose >100 mg/dL) or diabetes mellitus
- Conditions affecting appetite or energy expenditure (e.g., Cushing's syndrome, uncontrolled hyper-/hypothyroidism)
- Gastrointestinal disorders that impact nutrient absorption (e.g., inflammatory bowel disease, malabsorption syndromes, ulcers)
- Psychiatric conditions influencing eating behavior (e.g., active depression, anorexia nervosa, bulimia nervosa, borderline personality disorder)
- Acute, unstable cardiovascular disease requiring hospitalization within the last 6 months (e.g., stent placement)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Identification of Metabolic Phenotypes in Lean vs. Obese Individuals
Time frame: Measured at baseline (Day 1) and after 24-hour fasting (Day 2)
We aim to determine whether individuals with obesity (BMI >30 kg/m²) exhibit a more "thrifty" metabolic phenotype (lower resting metabolic rate [RMR] after 24-hour fasting and reduced diet-induced thermogenesis [DIT]) compared to lean individuals (BMI 18.5-22 kg/m²) who have trouble gaining weight, hypothesized to show a more "spendthrift" metabolic phenotype (increased RMR after fasting and higher DIT). RMR is measured via indirect calorimetry before and after a 24-hour fast, followed by a high-calorie, low-protein meal test to assess DIT.
6 secondary outcomes
Correlation Between Fasting-Induced Energy Expenditure Changes and Diet-Induced Thermogenesis
Time frame: Baseline (Day 1), post-fasting (Day 2), and after the meal test (Day 2)
Assessment of Metabolic Flexibility via Respiratory Quotient
Time frame: Baseline (Day 1), post-fasting (Day 2), and after the meal test (Day 2)
Correlation Between Weight Gain at 12-Month Follow-Up and Initial Metabolic Phenotype
Time frame: 12-month follow-up
Correlation Between Weight Gain at 12-Month Follow-Up and Diet-Induced Thermogenesis
Time frame: 12-month follow-up
Correlation Between Meal Test Diet-Induced Thermogenesis and Fibroblast Growth Factor 21 (FGF-21) Secretion
Time frame: After the meal test (Day 2)
Correlation Between Gut Hormones and Changes in Energy Expenditure
Time frame: Baseline (Day 1), after 24-hour fast (Day 2), and after the meal test (Day 2)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Jul 2026.
- Study Website (German)Link provided by the sponsor.
- Individual participant dataSharing planned: Undecided
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity and Overweight, run by University Hospital Schleswig-Holstein at 1 site in Germany.
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 4 inclusion and 16 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: finished, as of the sponsor's last update on 7 Jul 2026. 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 Germany. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Identification of Metabolic Phenotypes in Lean vs. Obese Individuals (time frame: Measured at baseline (Day 1) and after 24-hour fasting (Day 2)). 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 7 Jul 2026.