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Active, Not Recruiting

NCT Number: NCT07345429

One-Year Outcomes After Conversion Bariatric Surgery

Obesity is a growing global public health problem, and bariatric surgery is currently the most effective treatment for achieving sustained weight loss and improving obesity-related comorbidities. However, a subset of patients experience inadequate weight loss or weight regain following primary bariatric surgery, which may lead to the recurrence of metabolic complications and reduced quality of life. In such cases, conversion bariatric surgery, defined as the surgical conversion from one bariatric procedure to another, is considered an important therapeutic option. Despite the increasing number of conversion procedures, comprehensive longitudinal data evaluating anthropometric, biochemical, and nutritional outcomes after conversion bariatric surgery remain limited.

This study aims to prospectively evaluate individuals undergoing conversion bariatric surgery due to weight regain following primary bariatric surgery. Anthropometric measurements, biochemical parameters, and nutritional status will be assessed preoperatively and at 1 year after surgery. By evaluating weight loss outcomes together with metabolic and nutritional changes, this study seeks to provide clinically relevant evidence to guide postoperative follow-up strategies, optimize nutritional management, and support multidisciplinary care in patients undergoing conversion bariatric surgery.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Obesity & Overweight Bariatric Surgery Body Weight Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Revisional Bariatric Surgery Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Mudanya Univesity

Osmangazi, Bursa, 16160, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults aged 18-45 years
  • Previously underwent bariatric surgery
  • Subsequently underwent conversion bariatric surgery due to suboptimal clinical response

Suboptimal clinical response defined as either:

  • Suboptimal Clinical Response (SCR): maximum total weight loss (TWL%) of <20% within 18 months after metabolic and bariatric surgery
  • Recurrent Weight Gain (RWG): regaining >30% of initial postoperative weight loss after achieving initial weight reduction

Exclusion criteria

  • Pregnancy or lactation
  • Presence of acute illness or infection
  • Comorbid conditions that could limit treatment efficacy or compromise safety
  • Participation in professional athletic activity

Treatment and study plan

Primary outcomes

  1. Change in Body Composition Parameters

    Time frame: Preoperative baseline and postoperative 1 year

    Body composition parameters including fat mass, fat percentage, fat-free mass, fat-free mass percentage, skeletal muscle mass, muscle percentage, and extracellular water to total body water ratio assessed using multi-frequency bioelectrical impedance analysis (BIA).

  2. Change in Body Weight

    Time frame: Preoperative baseline and postoperative 1 year

    Change in body weight (kg) measured using a digital scale with participants wearing light clothing and no shoes.

  3. Change in Body Mass Index (BMI)

    Time frame: Preoperative baseline and postoperative 1 year

    Change in body mass index (kg/m²) calculated from measured body weight and height.

  4. Percentage of Total Weight Loss

    Time frame: postoperative 1 year

    Percentage of total weight loss calculated as [(preoperative weight - postoperative weight) / preoperative weight] × 100.

  5. Percentage of Excess Weight Loss

    Time frame: postoperative 1 year

    Percentage of excess weight loss calculated as [(preoperative weight - postoperative weight) / (preoperative weight - ideal body weight)] × 100, with ideal body weight defined as a BMI of 25 kg/m².

  6. Change in Waist Circumference

    Time frame: Preoperative baseline and postoperative 1 year

    Waist circumference (cm) measured in the standing position using a non-elastic measuring tape at the midpoint between the lowest rib and the iliac crest.

  7. Change in Hip Circumference

    Time frame: Preoperative baseline and postoperative 1 year

    Hip circumference (cm) measured in the standing position at the point of maximum protrusion of the gluteal muscles using a non-elastic measuring tape.

  8. Change in Body Fat Percentage (%)

    Time frame: Preoperative baseline and postoperative 1 year

    Body fat percentage measured using multi-frequency bioelectrical impedance analysis (BIA).

  9. Change in Fat-Free Mass (kg)

    Time frame: Preoperative baseline and postoperative 1 year

    Fat-free mass measured using multi-frequency bioelectrical impedance analysis (BIA).

  10. Change in Skeletal Muscle Mass (kg)

    Time frame: Preoperative baseline and postoperative 1 year

    Skeletal muscle mass measured using multi-frequency bioelectrical impedance analysis (BIA).

Secondary outcomes

  1. Change in Fasting Plasma Glucose

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in fasting plasma glucose levels measured from venous blood samples.

  2. Change in Alanine Aminotransferase (ALT)

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in alanine aminotransferase (ALT) levels measured from venous blood samples.

  3. Change in Hematological Parameters

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in hemoglobin and hematocrit levels measured from venous blood samples.

  4. Change in Iron Status Parameters

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in serum ferritin, serum iron, and total iron-binding capacity levels measured from venous blood samples.

  5. Change in Micronutrient and Electrolyte Levels

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in serum vitamin B12, folic acid, magnesium, total calcium, sodium, and potassium levels measured from venous blood samples.

  6. Change in Fasting Insulin

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in fasting insulin levels measured from venous blood samples.

  7. Change in Glycated Hemoglobin (HbA1c)

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in glycated hemoglobin (HbA1c) levels measured from venous blood samples.

  8. Change in Total Cholesterol

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in total cholesterol levels measured from venous blood samples.

  9. Change in LDL Cholesterol

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in low-density lipoprotein (LDL) cholesterol levels measured from venous blood samples.

  10. Change in HDL Cholesterol

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in high-density lipoprotein (HDL) cholesterol levels measured from venous blood samples.

  11. Change in Triglyceride Levels

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in triglyceride levels measured from venous blood samples

  12. Change in Aspartate Aminotransferase (AST)

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in aspartate aminotransferase (AST) levels measured from venous blood samples.

  13. Change in Urea Levels

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in serum urea levels measured from venous blood samples.

  14. Change in Uric Acid Levels

    Time frame: Preoperative baseline and postoperative 1 year

    Changes in serum uric acid levels measured from venous blood samples.

Sponsors and collaborators

Lead sponsor

Medipol University

Other

Collaborators

  • Mudanya University

Registry information

Official study title

ONE-YEAR OUTCOMES OF ANTHROPOMETRIC, BIOCHEMICAL, AND NUTRITIONAL PARAMETERS AFTER CONVERSION BARIATRIC SURGERY

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Jan 15, 2026
Registry last updated
Feb 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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