ObesityNCT07290075
The Relationship Between Olfactory and Gustatory Senses, Hedonic Hunger, and Diet Quality After Bariatric Surgery
An observational study of Obesity and Taste Disorders, run by Hanife Köksal at 1 site in Turkey (Türkiye).
Trial summary
This cross-sectional observational study investigates the association between changes in olfactory and gustatory senses and hedonic hunger among individuals who have undergone bariatric surgery. The study also examines the effects of these sensory changes on diet quality and anthropometric measurements. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obesity, Taste Disorders, Smell Disorder
- What is being tested?
- Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)
- How many people
- 101 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jan 2024to 31 Jan 2025
- 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 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adults aged 18-65 years who have undergone bariatric surgery (Sleeve Gastrectomy or Roux-en-Y Gastric Bypass) at least 3 months prior to enrollment, recruited from patients followed in clinical nutrition and bariatric surgery outpatient clinics.
Who may be able to join
- Adults aged 18 to 65 years
- History of bariatric surgery (Sleeve Gastrectomy or Roux-en-Y Gastric Bypass)
- At least 3 months post-surgery at the time of study enrollment
- Able and willing to provide informed consent
Who cannot join
- Pregnancy
- History of neurological disorders affecting taste or smell
- Active upper respiratory infection at the time of assessment
- Severe psychiatric disorders that may impair participation
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Istanbul University, Faculty of Medicine, Department of Endocrinology and Metabolism
Istanbul, Capa, 34093
About this study
This cross-sectional observational study investigates the association between changes in olfactory and gustatory senses and hedonic hunger among individuals who have undergone bariatric surgery. The study also examines the effects of these sensory changes on diet quality and anthropometric measurements. Participants completed a structured questionnaire including sociodemographic and health information, dietary habits, a modified 33-item taste and smell assessment, the Power of Food Scale (PFS), the Mediterranean Diet Adherence Screener (MEDAS), the International Physical Activity Questionnaire (IPAQ), and anthropometric measurements.
Read the detailed description
Obesity is a chronic, multifactorial disease that negatively impacts health and quality of life. Bariatric surgery is an effective treatment option for severe obesity, leading to significant and sustained weight loss as well as improvement in obesity-related comorbidities.
Postoperative changes in taste and smell perception are frequently reported by bariatric patients and may influence food preferences, hedonic hunger, and overall diet quality. These sensory alterations can result from anatomical and hormonal changes after surgery, including altered gut hormone secretion (e.g., PYY, GLP-1, ghrelin) and bile acid metabolism, which affect appetite regulation and reward pathways.
This cross-sectional observational study evaluated adults aged 18-65 years who had undergone sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) at least three months prior to enrollment. Data collection included sociodemographic and health information, dietary habits, a modified 33-item taste and smell questionnaire, the Power of Food Scale (PFS) to assess hedonic hunger, the Mediterranean Diet Adherence Screener (MEDAS), the International Physical Activity Questionnaire (IPAQ), and anthropometric measurements. Nutrient intakes were analyzed according to the Türkiye Nutrition Guide (TÜBER-2022) reference values.
The primary objective was to determine the relationship between postoperative taste/smell changes and hedonic hunger. Secondary objectives included assessing the association between sensory perception and Mediterranean diet adherence, anthropometric parameters, and nutrient adequacy by surgery type. Findings from this study may guide the development of personalized nutritional follow-up protocols to improve long-term outcomes in bariatric patients.
- Conditions
- Obesity, Taste Disorders, Smell Disorder
- Being tested
- Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)
- Keywords
- Hedonic Hunger, bariatric surgery outcomes, Mediterranean Diet, Nutrient Adequacy, Power of Food Scale (PFS), Taste and Smell Questionnaire, MEDAS
- Medical subject headings
- Obesity, Taste Disorders, Olfaction Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)Other
Participants who have undergone sleeve gastrectomy ≥3 months prior to study enrollment; and Participants who have undergone Roux-en-Y gastric bypass ≥3 months prior to study enrollment.
| Study group | Role | What they receive |
|---|---|---|
| Sleeve Gastrectomy (SG) | Participants who underwent sleeve gastrectomy at least 3 months prior to enrollment. Receives: Other: Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) | |
| Roux-en-Y Gastric Bypass (RYGB) | Participants who underwent Roux-en-Y gastric bypass at least 3 months prior to enrollment. Receives: Other: Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Power of Food Scale (PFS) Score
Hedonic hunger assessed using the Power of Food Scale (range: 1-5; higher scores indicate greater hedonic hunger).
Measured: Baseline (Day 1, at study enrollment)
Modified 33-item Taste and Smell Questionnaire Score
Changes in taste and smell perception assessed using a modified 33-item questionnaire (range: 0-33; higher scores indicate more pronounced sensory changes).
Measured: Baseline (≥3 months after bariatric surgery, at study enrollment)
Secondary outcomes (7)
Mediterranean Diet Adherence Screener (MEDAS) Score
Adherence to the Mediterranean diet assessed using the 14-item MEDAS questionnaire (range: 0-14; higher scores indicate greater adherence).
Measured: Baseline (≥3 months after bariatric surgery, at study enrollment)
Body Mass Index (BMI)
BMI calculated as weight (kg) / height (m²).
Measured: Baseline (Day 1, at study enrollment)
Waist-to-Hip Ratio (WHR)
WHR calculated as waist circumference (cm) / hip circumference (cm).
Measured: Baseline (Day 1, at study enrollment)
Energy Intake Adequacy (% of TÜBER-2022 reference)
Daily energy intake adequacy compared to TÜBER-2022 reference values.
Measured: Baseline (Day 1, at study enrollment)
Protein Intake Adequacy (% of TÜBER-2022 reference)
Daily protein intake adequacy compared to TÜBER-2022 reference values.
Measured: Baseline (Day 1, at study enrollment)
Micronutrient Intake Adequacy (e.g., iron, folate, vitamin E; % of TÜBER-2022 reference)
Micronutrient intake adequacy compared to TÜBER-2022 reference values.
Measured: Baseline (Day 1, at study enrollment)
Nutrient Adequacy Score (based on TÜBER-2022 reference values)
Composite score reflecting the percentage adequacy of daily energy, macronutrient, and micronutrient intakes compared to TÜBER-2022 reference values. Higher scores indicate greater adequacy.
Measured: Baseline (Day 1, at study enrollment)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Dec 2025
- Study start1 Jan 2024
- Primary completion30 Nov 2024
- Study completion31 Jan 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies 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
- Retrospective
- Enrolment
- 101 participants (actual)
Sponsor and investigators
- Lead sponsor
- Hanife Köksal
- Sponsor type
- University, hospital or other
- Collaborators
- Uskudar University
- Responsible party
- Sponsor-investigator, Hanife Köksal, Istanbul University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07290075
- Sponsor's protocol ID
- USK-NUTR-HK01
- Status last verified
- Dec 2025
- First submitted
- 12 Aug 2025
- Last updated
- 17 Dec 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: No - Individual participant data (IPD) will not be shared due to privacy concerns and lack of prior consent for public data sharing from study participants. Only aggregated results will be available in publications.
Study at a glance
From the registry record, last updated by the sponsor on 17 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Relationship Between Olfactory and Gustatory Senses, Hedonic Hunger, and Diet Quality After Bariatric Surgery
- ClinicalTrials.gov ID
- NCT07290075
- Acronym / sponsor ID
- USK-NUTR-HK01
- Conditions
- Obesity, Taste Disorders, Smell Disorder
- Keywords
- Hedonic Hunger, bariatric surgery outcomes, Mediterranean Diet, Nutrient Adequacy, Power of Food Scale (PFS), Taste and Smell Questionnaire, MEDAS
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 101 participants (actual)
- Lead sponsor
- Hanife KöksalUniversity, hospital or other
- Collaborators
- Uskudar University
- Study start
- 1 Jan 2024 (actual)
- Primary completion
- 30 Nov 2024 (actual)
- Study completion
- 31 Jan 2025 (actual)
- First posted
- 17 Dec 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 cross-sectional observational study investigates the association between changes in olfactory and gustatory senses and hedonic hunger among individuals who have undergone bariatric surgery. The study also examines the effects of these sensory changes on diet quality and anthropometric measurements. Participants completed a structured questionnaire including sociodemographic and health information, dietary habits, a modified 33-item taste and smell assessment, the Power of Food Scale (PFS), the Mediterranean Diet Adherence Screener (MEDAS), the International Physical Activity Questionnaire (IPAQ), and anthropometric measurements.
Detailed description
Obesity is a chronic, multifactorial disease that negatively impacts health and quality of life. Bariatric surgery is an effective treatment option for severe obesity, leading to significant and sustained weight loss as well as improvement in obesity-related comorbidities.
Postoperative changes in taste and smell perception are frequently reported by bariatric patients and may influence food preferences, hedonic hunger, and overall diet quality. These sensory alterations can result from anatomical and hormonal changes after surgery, including altered gut hormone secretion (e.g., PYY, GLP-1, ghrelin) and bile acid metabolism, which affect appetite regulation and reward pathways.
This cross-sectional observational study evaluated adults aged 18-65 years who had undergone sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) at least three months prior to enrollment. Data collection included sociodemographic and health information, dietary habits, a modified 33-item taste and smell questionnaire, the Power of Food Scale (PFS) to assess hedonic hunger, the Mediterranean Diet Adherence Screener (MEDAS), the International Physical Activity Questionnaire (IPAQ), and anthropometric measurements. Nutrient intakes were analyzed according to the Türkiye Nutrition Guide (TÜBER-2022) reference values.
The primary objective was to determine the relationship between postoperative taste/smell changes and hedonic hunger. Secondary objectives included assessing the association between sensory perception and Mediterranean diet adherence, anthropometric parameters, and nutrient adequacy by surgery type. Findings from this study may guide the development of personalized nutritional follow-up protocols to improve long-term outcomes in bariatric patients.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Sleeve Gastrectomy (SG) | – | Other: Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)Participants who underwent sleeve gastrectomy at least 3 months prior to enrollment. |
| Roux-en-Y Gastric Bypass (RYGB) | – | Other: Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)Participants who underwent Roux-en-Y gastric bypass at least 3 months prior to enrollment. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adults aged 18-65 years who have undergone bariatric surgery (Sleeve Gastrectomy or Roux-en-Y Gastric Bypass) at least 3 months prior to enrollment, recruited from patients followed in clinical nutrition and bariatric surgery outpatient clinics.
Key inclusion criteria (4 listed)
- Adults aged 18 to 65 years
- History of bariatric surgery (Sleeve Gastrectomy or Roux-en-Y Gastric Bypass)
- At least 3 months post-surgery at the time of study enrollment
- Able and willing to provide informed consent
Key exclusion criteria (4 listed)
- Pregnancy
- History of neurological disorders affecting taste or smell
- Active upper respiratory infection at the time of assessment
- Severe psychiatric disorders that may impair participation
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 |
|---|---|---|
| Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB)Participants who have undergone sleeve gastrectomy ≥3 months prior to study enrollment; and Participants who have undergone Roux-en-Y gastric bypass ≥3 months prior to study enrollment. | Other | Roux-en-Y Gastric Bypass (RYGB), Sleeve Gastrectomy (SG) |
Primary outcome
Power of Food Scale (PFS) Score
Time frame: Baseline (Day 1, at study enrollment)
Hedonic hunger assessed using the Power of Food Scale (range: 1-5; higher scores indicate greater hedonic hunger).
Modified 33-item Taste and Smell Questionnaire Score
Time frame: Baseline (≥3 months after bariatric surgery, at study enrollment)
Changes in taste and smell perception assessed using a modified 33-item questionnaire (range: 0-33; higher scores indicate more pronounced sensory changes).
7 secondary outcomes
Mediterranean Diet Adherence Screener (MEDAS) Score
Time frame: Baseline (≥3 months after bariatric surgery, at study enrollment)
Body Mass Index (BMI)
Time frame: Baseline (Day 1, at study enrollment)
Waist-to-Hip Ratio (WHR)
Time frame: Baseline (Day 1, at study enrollment)
Energy Intake Adequacy (% of TÜBER-2022 reference)
Time frame: Baseline (Day 1, at study enrollment)
Protein Intake Adequacy (% of TÜBER-2022 reference)
Time frame: Baseline (Day 1, at study enrollment)
Micronutrient Intake Adequacy (e.g., iron, folate, vitamin E; % of TÜBER-2022 reference)
Time frame: Baseline (Day 1, at study enrollment)
Nutrient Adequacy Score (based on TÜBER-2022 reference values)
Time frame: Baseline (Day 1, at study enrollment)
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 17 Dec 2025.
- Individual participant dataSharing planned: No. No - Individual participant data (IPD) will not be shared due to privacy concerns and lack of prior consent for public data sharing from study participants. Only aggregated results will be available in publications.
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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 Taste Disorders, run by Hanife Köksal at 1 site in Turkey (Türkiye).
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: finished, as of the sponsor's last update on 17 Dec 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 Turkey (Türkiye). 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?
Power of Food Scale (PFS) Score (time frame: Baseline (Day 1, at study enrollment)). The study lists 2 primary outcomes in all. 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 17 Dec 2025.