Collagen Supplements and Post-MBS Muscle Mass/Body Image

Relationship Between Collagen-Containing Supplement Use and Muscle Mass and Body Image Following Metabolic and Bariatric Surgery: A Prospective Observational Study

This prospective, observational cohort study aims to evaluate whether the use of collagen-containing supplements is associated with differences in muscle mass, body composition, and body image among patients who have undergone sleeve gastrectomy (SG). The study will be conducted at the General Surgery outpatient clinic of a private hospital in Bursa, Türkiye, between May 2026 and March 2027, and will enroll adult patients (aged 18-65 years) who meet current ASMBS/IFSO eligibility criteria for metabolic and bariatric surgery.

Participants will be naturally allocated into two observational groups based on their own choice to use or not use collagen-containing supplements; no supplement will be provided or recommended by the study team, and no intervention will be made to participants' standard clinical care. All patients will be followed according to routine clinical practice preoperatively and at 2 weeks, 1 month, 3 months, and 6 months postoperatively.

Primary outcome measures include anthropometric parameters (body weight, BMI, fat mass, fat mass percentage, fat-free mass, muscle mass, percentage of weight loss, percentage of excess weight loss, waist and hip circumference) assessed via bioelectrical impedance analysis (Tanita MC-780 MA), and body image assessed using the Turkish-validated Body Shape Questionnaire (BSQ). Secondary outcomes include biochemical parameters, comorbidities, and macronutrient intake data obtained from 3-day dietary records analyzed using the BEBİS nutrition software.

The study hypothesizes that patients using collagen-containing supplements will show significant differences in muscle mass and body composition parameters compared with non-users, and that supplement use will be significantly associated with BSQ scores. A sample size of approximately 52 participants per group was calculated using G*Power 3.1 (one-way ANOVA, Cohen's f = 0.25, α = 0.05, power = 0.80).

Study Overview

• Status: Recruiting
• Conditions: Body Composition; Body Image; Collagen Protein; Bariatric Surgery; Obesity & Overweight; Muscle Composition; Metabolic and Bariatric Surgery
• Intervention / Treatment: Dietary supplement: Collagen-containing supplement

• Study Type: Observational
• Enrollment (Estimated): 52

Contacts and Locations

• Study Contact: Name: Seher Şen, Assistant Professor; Phone Number: +905393919700; Email: seherdalli@gmail.com
• Study Contact Backup: Name: Emre Şen, Master's degree graduate; Phone Number: 0 532 163 30 87

Study Locations

• Turkey (Türkiye)
  • Yıldırım
    • Bursa, Yıldırım, Turkey (Türkiye)
      • Recruiting
      • Yıldırım Doruk Hastanesi
      • Contact: Phone Number: 05393919700; Email: seher.sen@mudanya.edu.tr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Adult patients aged 18-65 years who underwent sleeve gastrectomy and are under routine postoperative follow-up at the General Surgery outpatient clinic of a private hospital in Bursa, Türkiye. Eligible patients meet current ASMBS/IFSO criteria for metabolic and bariatric surgery (BMI ≥ 35 kg/m², or BMI 30-34.9 kg/m² with an obesity-related metabolic comorbidity). Participants are naturally grouped according to their own preference to use or not use a collagen-containing supplement following surgery.

Description

Inclusion Criteria:

• Patients with a BMI ≥ 35 kg/m², regardless of the presence of comorbidities
• Patients with a BMI of 30-34.9 kg/m² who have an obesity-related metabolic disease and are considered eligible for surgical treatment
• Patients who have undergone metabolic and bariatric surgery (MBS) in accordance with current ASMBS/IFSO guidelines (Eisenberg et al., 2022)
• Patients under regular postoperative follow-up
• Age 18-65 years

Exclusion Criteria:

• Inflammatory bowel disease
• History of upper gastrointestinal bleeding
• Severe psychiatric disorders
• Active cancer diagnosis
• Pregnancy or breastfeeding
• Alcohol or substance dependence
• Physical limitations preventing participation in exercise

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
1. Grup; Group/Cohort Label: Collagen Supplement Users (Kolajen Kullananlar) Description: Participants who, based on their own preference, use a collagen-containing supplement product following sleeve gastrectomy, without any intervention or recommendation from the study team.	Dietary supplement: Collagen-containing supplement; Collagen-containing supplement products used at the participants' own discretion following sleeve gastrectomy. The type of product, daily dosage, and duration of use were self-reported by participants
2. Grup; Group/Cohort Label: Non-Users of Collagen Supplement (Kolajen Kullanmayanlar) Description: Participants who do not use any collagen-containing supplement product following sleeve gastrectomy, followed under routine clinical care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Body Weight	Body weight (kg) measured using a Tanita MC-780 MA device.	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months
Change in Body Shape Questionnaire (BSQ) Score	Body image concerns were assessed using the Body Shape Questionnaire (BSQ-34), a validated instrument for the Turkish population. This 34-item self-report scale evaluates weight-related concerns and dissatisfaction with body shape over the preceding four weeks. Each item is scored from 1 (never) to 6 (always), with a total score range of 34 to 204. Higher scores indicate greater dissatisfaction with body shape, i.e., a worse outcome.	Preoperative and postoperative 6 months
Change in Body Mass Index (BMI)	BMI calculated as body weight (kg) divided by height squared (m²).	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months
Percentage of Total Weight Loss (%TWL)	Calculated as (preoperative weight - postoperative weight) / preoperative weight × 100.	Postoperative and 6 months
Percentage of Excess Weight Loss (%EWL)	Calculated as (preoperative weight - postoperative weight) / (preoperative weight - ideal weight) × 100. Ideal body weight was calculated assuming a BMI of 25 kg/m².	Postoperative and 6 months
Change in Fat Mass	Fat mass (kg) assessed by multi-frequency bioelectrical impedance analysis (BIA) using a Tanita MC-780 MA device.	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months
Change in Fat Mass Percentage	Fat mass expressed as a percentage of total body weight, assessed by bioelectrical impedance analysis (BIA) using a Tanita MC-780 MA device.	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months
Change in Muscle Mass	Muscle mass (kg) assessed by bioelectrical impedance analysis (BIA) using a Tanita MC-780 MA device.	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months
Change in Muscle Mass Percentage	Muscle mass expressed as a percentage of total body weight, assessed by bioelectrical impedance analysis (BIA) using a Tanita MC-780 MA device.	Preoperative, and postoperative 2 weeks, 1 month, 3 months, and 6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Fasting Blood Glucose	Fasting blood glucose (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Fasting Insulin	Fasting insulin (µIU/mL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in HbA1c	Glycated hemoglobin (HbA1c, %) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in LDL Cholesterol	LDL cholesterol (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in HDL Cholesterol	HDL cholesterol (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Triglycerides	Triglycerides (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and postoperative 6 months
Change in Total Cholesterol	Total cholesterol (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and postoperative 6 months
Change in ALT	Alanine aminotransferase (ALT, U/L) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in AST	Aspartate aminotransferase (AST, U/L) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Uric Acid	Uric acid (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Urea	Urea (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Hemoglobin	Hemoglobin (g/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Hematocrit	Hematocrit (%) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Ferritin	Ferritin (ng/mL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Serum Iron	Serum iron (µg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Vitamin B12	Vitamin B12 (pg/mL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Folic Acid	Folic acid (ng/mL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Magnesium	Magnesium (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Total Calcium	Total calcium (mg/dL) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Serum Sodium	Serum sodium (mEq/L) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months
Change in Serum Potassium	Serum potassium (mEq/L) obtained from routine clinical laboratory follow-up.	Preoperative and 6 months

Collaborators and Investigators

• Sponsor: Mudanya University

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2026
• Primary Completion (Estimated): January 10, 2027
• Study Completion (Estimated): February 10, 2027

Study Registration Dates

• First Submitted: July 29, 2026
• First Submitted That Met QC Criteria: September 3, 2026
• First Posted (Actual): September 9, 2026

Study Record Updates

• Last Update Posted (Actual): September 9, 2026
• Last Update Submitted That Met QC Criteria: September 3, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Body Composition; Bariatric Surgery; Muscle Mass; Collagen Supplementation
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Overweight; Obesity
• Other Study ID Numbers: MUDU-SBE-SS-05

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared, as this was not planned or consented to as part of the study protocol. Data confidentiality was assured to participants at the time of enrollment, and no data sharing infrastructure or agreement is in place beyond the study team.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No