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.
Study Type
OBSERVATIONAL
Enrollment
14
Mudanya Univesity
Osmangazi, Bursa, Turkey (Türkiye)
Change in Body Composition Parameters
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).
Time frame: Preoperative baseline and postoperative 1 year
Change in Body Weight
Change in body weight (kg) measured using a digital scale with participants wearing light clothing and no shoes.
Time frame: Preoperative baseline and postoperative 1 year
Change in Body Mass Index (BMI)
Change in body mass index (kg/m²) calculated from measured body weight and height.
Time frame: Preoperative baseline and postoperative 1 year
Percentage of Total Weight Loss
Percentage of total weight loss calculated as \[(preoperative weight - postoperative weight) / preoperative weight\] × 100.
Time frame: postoperative 1 year
Percentage of Excess Weight Loss
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.
Time frame: postoperative 1 year
Change in Waist Circumference
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.
Time frame: Preoperative baseline and postoperative 1 year
Change in Hip Circumference
Hip circumference (cm) measured in the standing position at the point of maximum protrusion of the gluteal muscles using a non-elastic measuring tape.
Time frame: Preoperative baseline and postoperative 1 year
Change in Body Fat Percentage (%)
Body fat percentage measured using multi-frequency bioelectrical impedance analysis (BIA).
Time frame: Preoperative baseline and postoperative 1 year
Change in Fat-Free Mass (kg)
Fat-free mass measured using multi-frequency bioelectrical impedance analysis (BIA).
Time frame: Preoperative baseline and postoperative 1 year
Change in Skeletal Muscle Mass (kg)
Skeletal muscle mass measured using multi-frequency bioelectrical impedance analysis (BIA).
Time frame: Preoperative baseline and postoperative 1 year
Change in Fasting Plasma Glucose
Changes in fasting plasma glucose levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Alanine Aminotransferase (ALT)
Changes in alanine aminotransferase (ALT) levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Hematological Parameters
Changes in hemoglobin and hematocrit levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Iron Status Parameters
Changes in serum ferritin, serum iron, and total iron-binding capacity levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Micronutrient and Electrolyte Levels
Changes in serum vitamin B12, folic acid, magnesium, total calcium, sodium, and potassium levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Fasting Insulin
Changes in fasting insulin levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Glycated Hemoglobin (HbA1c)
Changes in glycated hemoglobin (HbA1c) levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Total Cholesterol
Changes in total cholesterol levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
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Change in LDL Cholesterol
Changes in low-density lipoprotein (LDL) cholesterol levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in HDL Cholesterol
Changes in high-density lipoprotein (HDL) cholesterol levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Triglyceride Levels
Changes in triglyceride levels measured from venous blood samples
Time frame: Preoperative baseline and postoperative 1 year
Change in Aspartate Aminotransferase (AST)
Changes in aspartate aminotransferase (AST) levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Urea Levels
Changes in serum urea levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year
Change in Uric Acid Levels
Changes in serum uric acid levels measured from venous blood samples.
Time frame: Preoperative baseline and postoperative 1 year