ObesityDIBASHNCT06538948
Direct Measurement of Ingestive Behaviour in Relation to Sex Differences and Gastrointestinal Hormone Levels in Patients After Metabolic and Bariatric Surgery
An observational study of Obesity, run by University of Zurich at 2 sites in Switzerland.
Trial summary
Bariatric surgery (BS), especially procedures like Sleeve Gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), is the most effective treatment for obesity. Yet, the exact mechanisms governing its effect are somewhat elusive, with current research mainly focusing on post-operative food intake outcomes based on… Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Obesity
- What is being tested?
- Bariatric Surgery
- Type of treatment
- Surgery or procedure
- How many people
- 420 participants
- Where
- 2 sitesSwitzerland
- Study dates
- 13 Feb 2024to 31 Dec 2027
- Phase
- Observational
- 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 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Participants with obesity and scheduled for bariatric surgery are recruited consecutively at the outpatient clinic of bariatric surgery at the University Hospital Zurich. Participants with obesity not scheduled for surgery are recruited at the private clinic "Adimed" in Winterthur. Participants without obesity are recruited from students, employees and faculty of the Faculty of Medicine of the University of Zurich.
Who may be able to join
- Age ≥ 18 year
- BMI ≥ 35 kg/m2 for patients with planned RYGB or SG operation
- BMI ≥ 30 kg/m2 for external controls affected by obesity but no planned RYGB or SG within the next 12 months, and
- BMI ≥ 18.5 kg/m2 and ≤ 24.9 kg/m2 for controls without obesity.
Who cannot join
- history of previous bariatric operations and/ or revisional surgery (e.g., alteration of limb lengths after primary RYGB),
- smoking,
- established diagnosis of type 1 or 2 diabetes mellitus, and
- polycystic ovary syndrome (PCOS).
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland2 sites, 2 recruiting
- Recruiting
Hospital Männedorf
Männedorf, Canton of Zurich, 8708
Angela Munson, +41449222511, a.munson@spitalmaennedorf.ch
- Recruiting
University Hospital Zurich, Department of Surgery and Transplantation
Zurich, Canton of Zurich, 8091
Hatice Ucar, +41 44 255 54 63, hatice.ucar@usz.ch
About this study
Bariatric surgery (BS), especially procedures like Sleeve Gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), is the most effective treatment for obesity. Yet, the exact mechanisms governing its effect are somewhat elusive, with current research mainly focusing on post-operative food intake outcomes based on self-reported data, which might not fully capture the nuanced changes in eating behaviours.
To address these gaps, our study plans to employ the newly developed "drinkometer", a device capable of analysing the intricate changes in drinking behaviour following BS. This tool promises to bring a more detailed perspective to the changes in ingestive behaviours, bypassing the inaccuracies of self-reporting methods. By expanding our research to encompass diverse patient demographics and examining potential links to physiological shifts like gut hormone level alterations, the study aims to provide a more rounded understanding of the long-term impacts of BS on eating behaviours.
Read the detailed description
HYPOTHESIS AND PRIMARY OBJECTIVE
So far, studies of ingestive behaviour in humans have produced ambiguous results. Moreover, direct measurements of ingestive behaviour in humans after BS are still rare and the roles of sex and gut hormones, as well as their relevance for clinical outcome parameters, such as body weight loss, remain elusive. A comprehensive understanding of how a given intervention such as BS affects food intake requires a detailed analysis of the ingestive behaviour itself, not simply the measurement of the outcome of the behaviour. In other words, the information on how the food is consumed is equally or even more important than the information on how much food has been ingested.
This study employs the drinkometer methodology to perform direct measurements of ingestive behaviour in male and female human patients after SG and RYGB along with parallel measurements of postprandial gut hormone levels. Furthermore, this study investigates the clinical relevance of changes in ingestive behaviour by correlating microstructural parameters with body weight loss in a consecutive set of patients who received RYGB at the University Hospital Zurich five years before the time of recruitment.
Of note, the proposed experiments aim to test specific hypotheses regarding the behavioural mechanisms underlying potential changes in food intake after BS in humans. Thus, this research do not aim to identify how BS affects one or the other single microstructural parameters of eating or drinking. Instead, this study investigates how a given intervention that is known to substantially affect food intake behaviour - such as BS - alters the profile of a group of microstructural parameters of ingestive behaviour in humans. Given that ingestive behaviour represents the readout of the central nervous system mechanisms controlling energy intake (e.g., palatability, aversion, avoidance, satiation), the results of the proposed studies will inform the search for the underlying neural circuits in the brain that are specifically altered by BS. If there is no altered behaviour, there would be no point in investigating the underlying physiology. More specifically, this study aims to:
- Investigate longitudinal changes and differences in the ingestive behaviour of female patients before and within one year after either primary RYGB or primary SG (Study 1).
- Investigate a possible association between the ingestive behaviour and the prandial gut hormone levels of female patients before and within one year after either primary RYGB or SG (Study 1).
- Investigate a possible difference between the ingestive behaviour of female and male patients before and within one year after primary RYGB (Study 2).
- Investigate a possible association between the postoperatively achieved body weight loss of female and male patients 5 years after primary RYGB and ingestive behaviour (Study 3).
- Investigate, in a subset of responders and non-responders to primary RYGB, a possible association between postprandial gut hormone levels of female and male patients 5 years after primary RYGB and ingestive behaviour (Study 3).
PRIMARY AND SECONDARY ENDPOINTS
In the research protocol, the primary and secondary outcomes specific to each of the three studies planned within the research project have been described. Recognising that each study has its unique objectives and hypotheses, the outcomes have been specified distinctly for each study to ensure clarity and focus in the research approach.
For each of the three studies, the primary outcomes are those key results that the study is primarily designed to assess. These are the main effects or findings that are anticipated to provide the most significant insights into the research questions. Secondary outcomes, while still important, are additional results that can be explored after answering the main research questions. These might provide supplementary information, support the primary outcomes, or offer insights into other areas related to the main research question.
By presenting these outcomes separately for each study, this study aims to provide a structured and transparent overview of the research intentions, allowing for a clear understanding of the objectives and measures in each specific part of the project. This approach not only aids in maintaining the focus and integrity of each study but also assists in the clear communication of the research goals and methods.
PROJECT DESIGN
The proposed studies will test key elements of ingestive behaviour and their relation to pre- and postprandial levels of gut hormones as well as sex differences after the two most frequently performed bariatric operations. They will thus provide useful information for planning and conducting future trials in the field, such as optimal recruitment and retention strategies, intervention delivery, data collection methods and adherence to study protocols. The proposed studies will further provide empirical estimates of effect sizes of bariatric surgery and long-term associations of ingestive behaviour with gut hormones for post-bariatric body weight loss. The potential outcomes of Studies 1, 2 and 3 are conceptually different. Nevertheless, the results of these studies will complement each other as well as our findings from previous studies, and can be used to calculate sample sizes for future trials.
- Conditions
- Obesity
- Being tested
- Bariatric Surgery
- Keywords
- Obesity, Ingestive Behaviour, Bariatric Surgery, Gut Hormones, Drinkometer
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Bariatric SurgeryProcedure or surgery
The intervention is not assigned to the participant after recruitment in the study, rather the intervention is an inclusion criteria for participation in the study.
| Study group | Role | What they receive |
|---|---|---|
| Adult Females planned for RYGB surgery | Adult females leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Roux-en-Y Gastric Bypass Surgery Receives: Procedure: Bariatric Surgery | |
| Adult Females planned for SG surgery | Adult females leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Sleeve Gastrectomy Surgery Receives: Procedure: Bariatric Surgery | |
| Adult Females with Obesity | Adult females leaving with obesity with BMI between 30 and 50 kg/m2 but not scheduled for any procedures of bariatric surgery | |
| Adult Females with Normal-Weight | Adult females with normal weight with BMI between 18.5 and 24.9 kg/m2 | |
| Adult Males planned for RYGB surgery | Adult males leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Roux-en-Y Gastric Bypass Surgery Receives: Procedure: Bariatric Surgery | |
| Adult Males with Obesity | Adult males leaving with obesity with BMI between 30 and 50 kg/m2 but not scheduled for any procedures of bariatric surgery | |
| Adult Males with Normal-Weight | Adult males with normal weight with BMI between 18.5 and 24.9 kg/m2 | |
| Adult Females and Males 5 years after RYGB surgery | Adult Females and Males who underwent RYGB surgery 5 years before study recruitment and study measurements Receives: Procedure: Bariatric Surgery |
What is being measured
The primary outcome is the main question the study is designed to answer.
Drinkometer Measurement of Microstructural Parameters of Ingestive Behaviour, such as Suck Energy Intake and Burst Energy Intake.
Difference of the eleven microstructural parameters of ingestive behaviour within the cohorts with intervention at the end of follow-up compared to baseline measurements and differences between the cohorts with intervention and the cohorts without intervention will be measured with a drinkometer device. The microstructural parameters of ingestive behaviour are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description.
Measured: One year after bariatric surgery
Effect of the Gut Hormones in Plasma on the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device
This study investigates the effect of pre- and post-prandial levels of gut hormones on the eleven microstructural parameters of ingestive behavior. These are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description. The study focuses on the influence of the following gut hormones: leptin, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), amylin, peptide YY (PYY), and insulin. These hormone concentrations are measured both pre- and post-prandially in the blood and are expressed in their respective units of measure (e.g., leptin in ng/mL, ghrelin in pg/mL).
Measured: One year after bariatric surgery
Effect of Biological Sex (Male or Female) on the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device
This study investigates the effect of biological sex (male or female) on the eleven microstructural parameters of ingestive behavior. These parameters are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description. The study focuses on comparing these parameters between males and females to understand the influence of biological sex on ingestive behavior.
Measured: One year after bariatric surgery
Cluster identification
Identification of clusters of good and poor response to RYGB five years after surgery based on the variance of the single microstructural parameters of ingestive behaviour
Measured: Five years after bariatric surgery
Correlation of Percentage Excess Body Mass Index Loss with the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device Five Years After Roux-en-Y Gastric Bypass Surgery
This study aims to investigate the correlation between percentage excess body mass index (BMI) loss (%EBMIL) and microstructural parameters of ingestive behavior, measured using the Drinkometer device, five years after Roux-en-Y gastric bypass (RYGB) surgery. The eleven microstructural parameters considered are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s).
This study explores how these microstructural parameters of ingestive behavior correlate with the long-term success of RYGB surgery as indicated by %EBMIL. By understanding these correlations, we aim to gain insights into the behavioral mechanisms that contribute to the maintenance of weight loss post-surgery.
Measured: Five years after bariatric surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Aug 2024
- Study start13 Feb 2024
- Primary completion31 Aug 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for ObesityStudies of the same condition, open and under way.
- More trials run by University of ZurichThe sponsor's other registered studies.
- 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
- 420 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Zurich
- Sponsor type
- University, hospital or other
- Collaborators
- Florida State University, University College Dublin
- Responsible party
- Principal investigator, Marco Bueter, University of Zurich
- Investigators
- Marco Bueter, MD, DPhil, Principal investigator, University of Zurich
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06538948
- Sponsor's protocol ID
- 2023-02109
- Other IDs
- 2023
- Acronym
- DIBASH
- Status last verified
- May 2026
- First submitted
- 25 Jul 2024
- Last updated
- 18 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Gero D, Steinert RE, le Roux CW, Bueter M. Do Food Preferences Change After Bariatric Surgery? Curr Atheroscler Rep. 2017 Sep;19(9):38. doi: 10.1007/s11883-017-0674-x.
PubMed 28779431le Roux CW, Bueter M. The physiology of altered eating behaviour after Roux-en-Y gastric bypass. Exp Physiol. 2014 Sep;99(9):1128-32. doi: 10.1113/expphysiol.2014.078378.
PubMed 25210112Gero D, File B, Alceste D, Frick LD, Serra M, Ismaeil AE, Steinert RE, Spector AC, Bueter M. Microstructural changes in human ingestive behavior after Roux-en-Y gastric bypass during liquid meals. JCI Insight. 2021 Aug 9;6(15):e136842. doi: 10.1172/jci.insight.136842.
PubMed 34369388Alceste D, Serra M, Raguz I, Gero D, Thalheimer A, Widmer J, File B, Ismaeil A, Steinert RE, Spector AC, Bueter M. Association between microstructure of ingestive behavior and body weight loss in patients one year after Roux-en-Y gastric bypass. Physiol Behav. 2022 May 1;248:113728. doi: 10.1016/j.physbeh.2022.113728. Epub 2022 Feb 5.
PubMed 35134394Lutz TA, Bueter M. Physiological mechanisms behind Roux-en-Y gastric bypass surgery. Dig Surg. 2014;31(1):13-24. doi: 10.1159/000354319. Epub 2014 May 8.
PubMed 24819493Gero D, File B, Justiz J, Steinert RE, Frick L, Spector AC, Bueter M. Drinking microstructure in humans: A proof of concept study of a novel drinkometer in healthy adults. Appetite. 2019 Feb 1;133:47-60. doi: 10.1016/j.appet.2018.08.012. Epub 2018 Sep 1.
PubMed 30179650Serra M, File B, Alceste D, Raguz I, Gero D, Thalheimer A, Widmer J, Ismaeil A, Steinert RE, Spector AC, Bueter M. Burst-pause criterion derivation for drinkometer measurements of ingestive behavior. MethodsX. 2022 May 11;9:101726. doi: 10.1016/j.mex.2022.101726. eCollection 2022.
PubMed 35620756
Study at a glance
From the registry record, last updated by the sponsor on 18 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Direct Measurement of Ingestive Behaviour in Relation to Sex Differences and Gastrointestinal Hormone Levels in Patients After Metabolic and Bariatric Surgery
- ClinicalTrials.gov ID
- NCT06538948
- Acronym / sponsor ID
- DIBASH / 2023-02109
- Conditions
- Obesity
- Keywords
- Obesity, Ingestive Behaviour, Bariatric Surgery, Gut Hormones, Drinkometer
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 420 participants (estimated)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Collaborators
- Florida State University, University College Dublin
- Study start
- 13 Feb 2024 (actual)
- Primary completion
- 31 Aug 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 6 Aug 2024 (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.
Bariatric surgery (BS), especially procedures like Sleeve Gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), is the most effective treatment for obesity. Yet, the exact mechanisms governing its effect are somewhat elusive, with current research mainly focusing on post-operative food intake outcomes based on self-reported data, which might not fully capture the nuanced changes in eating behaviours.
To address these gaps, our study plans to employ the newly developed "drinkometer", a device capable of analysing the intricate changes in drinking behaviour following BS. This tool promises to bring a more detailed perspective to the changes in ingestive behaviours, bypassing the inaccuracies of self-reporting methods. By expanding our research to encompass diverse patient demographics and examining potential links to physiological shifts like gut hormone level alterations, the study aims to provide a more rounded understanding of the long-term impacts of BS on eating behaviours.
Detailed description
HYPOTHESIS AND PRIMARY OBJECTIVE
So far, studies of ingestive behaviour in humans have produced ambiguous results. Moreover, direct measurements of ingestive behaviour in humans after BS are still rare and the roles of sex and gut hormones, as well as their relevance for clinical outcome parameters, such as body weight loss, remain elusive. A comprehensive understanding of how a given intervention such as BS affects food intake requires a detailed analysis of the ingestive behaviour itself, not simply the measurement of the outcome of the behaviour. In other words, the information on how the food is consumed is equally or even more important than the information on how much food has been ingested.
This study employs the drinkometer methodology to perform direct measurements of ingestive behaviour in male and female human patients after SG and RYGB along with parallel measurements of postprandial gut hormone levels. Furthermore, this study investigates the clinical relevance of changes in ingestive behaviour by correlating microstructural parameters with body weight loss in a consecutive set of patients who received RYGB at the University Hospital Zurich five years before the time of recruitment.
Of note, the proposed experiments aim to test specific hypotheses regarding the behavioural mechanisms underlying potential changes in food intake after BS in humans. Thus, this research do not aim to identify how BS affects one or the other single microstructural parameters of eating or drinking. Instead, this study investigates how a given intervention that is known to substantially affect food intake behaviour - such as BS - alters the profile of a group of microstructural parameters of ingestive behaviour in humans. Given that ingestive behaviour represents the readout of the central nervous system mechanisms controlling energy intake (e.g., palatability, aversion, avoidance, satiation), the results of the proposed studies will inform the search for the underlying neural circuits in the brain that are specifically altered by BS. If there is no altered behaviour, there would be no point in investigating the underlying physiology. More specifically, this study aims to:
- Investigate longitudinal changes and differences in the ingestive behaviour of female patients before and within one year after either primary RYGB or primary SG (Study 1).
- Investigate a possible association between the ingestive behaviour and the prandial gut hormone levels of female patients before and within one year after either primary RYGB or SG (Study 1).
- Investigate a possible difference between the ingestive behaviour of female and male patients before and within one year after primary RYGB (Study 2).
- Investigate a possible association between the postoperatively achieved body weight loss of female and male patients 5 years after primary RYGB and ingestive behaviour (Study 3).
- Investigate, in a subset of responders and non-responders to primary RYGB, a possible association between postprandial gut hormone levels of female and male patients 5 years after primary RYGB and ingestive behaviour (Study 3).
PRIMARY AND SECONDARY ENDPOINTS
In the research protocol, the primary and secondary outcomes specific to each of the three studies planned within the research project have been described. Recognising that each study has its unique objectives and hypotheses, the outcomes have been specified distinctly for each study to ensure clarity and focus in the research approach.
For each of the three studies, the primary outcomes are those key results that the study is primarily designed to assess. These are the main effects or findings that are anticipated to provide the most significant insights into the research questions. Secondary outcomes, while still important, are additional results that can be explored after answering the main research questions. These might provide supplementary information, support the primary outcomes, or offer insights into other areas related to the main research question.
By presenting these outcomes separately for each study, this study aims to provide a structured and transparent overview of the research intentions, allowing for a clear understanding of the objectives and measures in each specific part of the project. This approach not only aids in maintaining the focus and integrity of each study but also assists in the clear communication of the research goals and methods.
PROJECT DESIGN
The proposed studies will test key elements of ingestive behaviour and their relation to pre- and postprandial levels of gut hormones as well as sex differences after the two most frequently performed bariatric operations. They will thus provide useful information for planning and conducting future trials in the field, such as optimal recruitment and retention strategies, intervention delivery, data collection methods and adherence to study protocols. The proposed studies will further provide empirical estimates of effect sizes of bariatric surgery and long-term associations of ingestive behaviour with gut hormones for post-bariatric body weight loss. The potential outcomes of Studies 1, 2 and 3 are conceptually different. Nevertheless, the results of these studies will complement each other as well as our findings from previous studies, and can be used to calculate sample sizes for future trials.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 8
| Arm | Type | Receives |
|---|---|---|
| Adult Females planned for RYGB surgery | – | Procedure: Bariatric SurgeryAdult females leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Roux-en-Y Gastric Bypass Surgery |
| Adult Females planned for SG surgery | – | Procedure: Bariatric SurgeryAdult females leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Sleeve Gastrectomy Surgery |
| Adult Females with Obesity | – | –Adult females leaving with obesity with BMI between 30 and 50 kg/m2 but not scheduled for any procedures of bariatric surgery |
| Adult Females with Normal-Weight | – | –Adult females with normal weight with BMI between 18.5 and 24.9 kg/m2 |
| Adult Males planned for RYGB surgery | – | Procedure: Bariatric SurgeryAdult males leaving with obesity with BMI between 35 and 50 kg/m2 and scheduled for Roux-en-Y Gastric Bypass Surgery |
| Adult Males with Obesity | – | –Adult males leaving with obesity with BMI between 30 and 50 kg/m2 but not scheduled for any procedures of bariatric surgery |
| Adult Males with Normal-Weight | – | –Adult males with normal weight with BMI between 18.5 and 24.9 kg/m2 |
| Adult Females and Males 5 years after RYGB surgery | – | Procedure: Bariatric SurgeryAdult Females and Males who underwent RYGB surgery 5 years before study recruitment and study measurements |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Participants with obesity and scheduled for bariatric surgery are recruited consecutively at the outpatient clinic of bariatric surgery at the University Hospital Zurich. Participants with obesity not scheduled for surgery are recruited at the private clinic "Adimed" in Winterthur. Participants without obesity are recruited from students, employees and faculty of the Faculty of Medicine of the University of Zurich.
Key inclusion criteria (4 listed)
- Age ≥ 18 year
- BMI ≥ 35 kg/m2 for patients with planned RYGB or SG operation
- BMI ≥ 30 kg/m2 for external controls affected by obesity but no planned RYGB or SG within the next 12 months, and
- BMI ≥ 18.5 kg/m2 and ≤ 24.9 kg/m2 for controls without obesity.
Key exclusion criteria (4 listed)
- history of previous bariatric operations and/ or revisional surgery (e.g., alteration of limb lengths after primary RYGB),
- smoking,
- established diagnosis of type 1 or 2 diabetes mellitus, and
- polycystic ovary syndrome (PCOS).
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 |
|---|---|---|
| Bariatric SurgeryThe intervention is not assigned to the participant after recruitment in the study, rather the intervention is an inclusion criteria for participation in the study. | Procedure or surgery | Adult Females and Males 5 years after RYGB surgery, Adult Females planned for RYGB surgery, Adult Females planned for SG surgery, Adult Males planned for RYGB surgery |
Primary outcome
Drinkometer Measurement of Microstructural Parameters of Ingestive Behaviour, such as Suck Energy Intake and Burst Energy Intake.
Time frame: One year after bariatric surgery
Difference of the eleven microstructural parameters of ingestive behaviour within the cohorts with intervention at the end of follow-up compared to baseline measurements and differences between the cohorts with intervention and the cohorts without intervention will be measured with a drinkometer device. The microstructural parameters of ingestive behaviour are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description.
Effect of the Gut Hormones in Plasma on the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device
Time frame: One year after bariatric surgery
This study investigates the effect of pre- and post-prandial levels of gut hormones on the eleven microstructural parameters of ingestive behavior. These are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description. The study focuses on the influence of the following gut hormones: leptin, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), amylin, peptide YY (PYY), and insulin. These hormone concentrations are measured both pre- and post-prandially in the blood and are expressed in their respective units of measure (e.g., leptin in ng/mL, ghrelin in pg/mL).
Effect of Biological Sex (Male or Female) on the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device
Time frame: One year after bariatric surgery
This study investigates the effect of biological sex (male or female) on the eleven microstructural parameters of ingestive behavior. These parameters are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). On this platform, a separate entry for the eleven microstructural parameters is not done to avoid redundancy in the description. The study focuses on comparing these parameters between males and females to understand the influence of biological sex on ingestive behavior.
Cluster identification
Time frame: Five years after bariatric surgery
Identification of clusters of good and poor response to RYGB five years after surgery based on the variance of the single microstructural parameters of ingestive behaviour
Correlation of Percentage Excess Body Mass Index Loss with the Microstructural Parameters of Ingestive Behaviour Measured with the Drinkometer Device Five Years After Roux-en-Y Gastric Bypass Surgery
Time frame: Five years after bariatric surgery
This study aims to investigate the correlation between percentage excess body mass index (BMI) loss (%EBMIL) and microstructural parameters of ingestive behavior, measured using the Drinkometer device, five years after Roux-en-Y gastric bypass (RYGB) surgery. The eleven microstructural parameters considered are: mean suck energy intake (kcal), mean suck duration (s), mean suck rate (kcal/s), mean suck maximal rate (kcal/s), burst number (n), burst energy intake (kcal), burst duration (s), burst rate (kcal/s), number of sucks per burst (n), inter-burst intervals (s), and inter-suck intervals (s). This study explores how these microstructural parameters of ingestive behavior correlate with the long-term success of RYGB surgery as indicated by %EBMIL. By understanding these correlations, we aim to gain insights into the behavioral mechanisms that contribute to the maintenance of weight loss post-surgery.
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 May 2026.
- Background: PubMed 28779431Gero D, Steinert RE, le Roux CW, Bueter M. Do Food Preferences Change After Bariatric Surgery? Curr Atheroscler Rep. 2017 Sep;19(9):38. doi: 10.1007/s11883-017-0674-x.
- Background: PubMed 25210112le Roux CW, Bueter M. The physiology of altered eating behaviour after Roux-en-Y gastric bypass. Exp Physiol. 2014 Sep;99(9):1128-32. doi: 10.1113/expphysiol.2014.078378.
- Background: PubMed 34369388Gero D, File B, Alceste D, Frick LD, Serra M, Ismaeil AE, Steinert RE, Spector AC, Bueter M. Microstructural changes in human ingestive behavior after Roux-en-Y gastric bypass during liquid meals. JCI Insight. 2021 Aug 9;6(15):e136842. doi: 10.1172/jci.insight.136842.
- Background: PubMed 35134394Alceste D, Serra M, Raguz I, Gero D, Thalheimer A, Widmer J, File B, Ismaeil A, Steinert RE, Spector AC, Bueter M. Association between microstructure of ingestive behavior and body weight loss in patients one year after Roux-en-Y gastric bypass. Physiol Behav. 2022 May 1;248:113728. doi: 10.1016/j.physbeh.2022.113728. Epub 2022 Feb 5.
- Background: PubMed 24819493Lutz TA, Bueter M. Physiological mechanisms behind Roux-en-Y gastric bypass surgery. Dig Surg. 2014;31(1):13-24. doi: 10.1159/000354319. Epub 2014 May 8.
- Background: PubMed 30179650Gero D, File B, Justiz J, Steinert RE, Frick L, Spector AC, Bueter M. Drinking microstructure in humans: A proof of concept study of a novel drinkometer in healthy adults. Appetite. 2019 Feb 1;133:47-60. doi: 10.1016/j.appet.2018.08.012. Epub 2018 Sep 1.
- Background: PubMed 35620756Serra M, File B, Alceste D, Raguz I, Gero D, Thalheimer A, Widmer J, Ismaeil A, Steinert RE, Spector AC, Bueter M. Burst-pause criterion derivation for drinkometer measurements of ingestive behavior. MethodsX. 2022 May 11;9:101726. doi: 10.1016/j.mex.2022.101726. eCollection 2022.
- Individual participant dataSharing planned: No
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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.
Marco Bueter, MD, DPhil principal investigator
University of Zurich
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity, run by University of Zurich at 2 sites in Switzerland.
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 4 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: looking for participants now, as of the sponsor's last update on 18 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Switzerland. 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 Marco Bueter, MD, DPhil (+41442558895, m.bueter@spitalmaennedorf.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Drinkometer Measurement of Microstructural Parameters of Ingestive Behaviour, such as Suck Energy Intake and Burst Energy Intake. (time frame: One year after bariatric surgery). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06538948, which also lists 7 linked publications.
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 May 2026.