8-Year Outcomes After Sleeve Gastrectomy

8-Year Outcomes After Sleeve Gastrectomy: Anthropometric, Biochemical, and Nutritional Evaluation

Obesity is a major global public health concern, and bariatric surgery is recognized as the most effective treatment for achieving sustained weight loss and improving obesity-related comorbidities. Sleeve gastrectomy (SG) is one of the most commonly performed bariatric procedures; however, long-term outcomes vary considerably among individuals. While some patients maintain satisfactory weight loss, others experience suboptimal weight loss or weight regain several years after surgery. Evidence suggests that long-term weight trajectories after SG may be influenced by metabolic changes, dietary habits, and lifestyle factors, highlighting the need for extended follow-up studies.

This observational cohort study aims to evaluate the long-term outcomes of individuals who underwent sleeve gastrectomy approximately 8 years ago. Anthropometric measurements, biochemical parameters, and nutritional status will be reassessed at an 8-year follow-up visit and compared with data obtained during the preoperative period and at postoperative 6 months. By examining within-subject changes over time, this study seeks to provide insight into the long-term sustainability of weight loss after sleeve gastrectomy and to identify metabolic and nutritional factors associated with long-term outcomes.

Study Overview

• Status: Active, not recruiting
• Conditions: Sleeve Gastrectomy; Obesity & Overweight

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Mudanya
    • Bursa, Mudanya, Turkey (Türkiye)
      • Mudanya Univesity

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population includes adults aged 18-65 years who underwent sleeve gastrectomy approximately eight years prior to enrollment and completed standard postoperative follow-up. Participants had available preoperative and 6-month postoperative anthropometric, biochemical, and nutritional data and were re-evaluated at 8 years after surgery to assess long-term outcomes.

Description

Inclusion Criteria:

• Adults aged 18-65 years
• Patients who underwent sleeve gastrectomy approximately 8 years prior to study enrollment
• Patients with available postoperative follow-up data at 6 months, including anthropometric measurements, biochemical parameters, and nutritional status assessments
• Patients willing to participate in long-term follow-up and attend in-person evaluations

Exclusion Criteria:

• Pregnancy or lactation
• Presence of acute illness or active infection at the time of evaluation
• Presence of acute illness, infection, or comorbid conditions that may limit study safety or validity, including malignancy, type 1 diabetes mellitus, renal or hepatic failure, recent stroke or myocardial infarction, nephrolithiasis, drug or alcohol abuse, eating disorders, severe depression or other major psychiatric disorders, inflammatory bowel disease, cardiac arrhythmias or heart failure, respiratory failure, or chronic systemic corticosteroid therapy.
• Professional athletes

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Sleeve Gastrectomy Long-Term Follow-up Cohort; This cohort includes adults who underwent sleeve gastrectomy between 2016 and 2017 and were re-evaluated approximately 8 years after surgery. Participants are followed observationally, with anthropometric measurements, biochemical parameters, and nutritional status assessed preoperatively, at postoperative 6 months, and at long-term (8-year) follow-up. No intervention is assigned as part of the study protocol; all surgical procedures were performed as part of routine clinical care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Fat Mass	Changes in fat mass measured using multi-frequency bioelectrical impedance analysis (BIA).	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Body Weight	Body weight measured using a calibrated digital scale with participants wearing light clothing and no shoes.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Body Mass Index (BMI)	BMI calculated as weight in kilograms divided by height in meters squared (kg/m²), measured using a wall-mounted stadiometer.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Waist Circumference	Waist circumference measured in centimeters at the midpoint between the subcostal margin and the iliac crest with participants standing upright.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Hip Circumference	Hip circumference measured in centimeters at the level of maximum gluteal protrusion.	Preoperative, postoperative 6 months, and postoperative 8 years
Percent Total Weight Loss (TWL%)	Calculated as [(preoperative weight - postoperative weight) / preoperative weight] × 100.	Postoperative 6 months and postoperative 8 years
Percent Excess Weight Loss (EWL%)	Calculated as [(preoperative weight - postoperative weight) / (preoperative weight - ideal body weight)] × 100, where ideal body weight corresponds to a BMI of 25 kg/m².	Postoperative 6 months and postoperative 8 years
Change in Body Fat Percentage	Changes in body fat percentage measured using multi-frequency bioelectrical impedance analysis (BIA).	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Skeletal Muscle Mass	Changes in skeletal muscle mass measured using multi-frequency bioelectrical impedance analysis (BIA).	Preoperative baseline, postoperative 6 months, and postoperative 8 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Fasting Plasma Glucose	Fasting plasma glucose measured after at least 8 hours of fasting using venous blood samples.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Fasting Insulin Levels	Fasting insulin levels measured from venous blood samples obtained after at least 8 hours of fasting.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Glycated Hemoglobin (HbA1c)	HbA1c levels measured to assess long-term glycemic control.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Lipid Profile Parameters	Serum lipid parameters including total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides measured after an overnight fast.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Liver Enzyme Levels	Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels measured from fasting blood samples.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Renal and Metabolic Biomarkers	Serum urea and uric acid levels measured to assess renal and metabolic function.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Serum Albumin	Changes in serum albumin levels measured from venous blood samples.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Micronutrient Levels	Serum levels of vitamin B12, folic acid, magnesium, total calcium, sodium, and potassium measured to assess micronutrient status.	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Physical Activity Level	Physical activity levels assessed using the International Physical Activity Questionnaire (IPAQ).	Preoperative, postoperative 6 months, and postoperative 8 years
Change in Fat-Free Mass	Changes in fat-free mass measured using multi-frequency bioelectrical impedance analysis (BIA).	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Total Protein	Changes in total serum protein levels measured from venous blood samples.	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Hemoglobin	Changes in hemoglobin levels measured from venous blood samples.	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Hematocrit	Changes in hematocrit levels measured from venous blood samples.	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Serum Ferritin	Changes in serum ferritin levels measured from venous blood samples.	Preoperative baseline, postoperative 6 months, and postoperative 8 years
Change in Serum Iron	Changes in serum iron levels measured from venous blood samples.	Preoperative baseline, postoperative 6 months, and postoperative 8 years

Collaborators and Investigators

• Sponsor: Medipol University
• Investigators: Study Director: Seher Şen, Mudanya University

Study record dates

Study Major Dates

• Study Start (Actual): June 12, 2025
• Primary Completion (Actual): January 10, 2026
• Study Completion (Estimated): March 10, 2026

Study Registration Dates

• First Submitted: December 18, 2025
• First Submitted That Met QC Criteria: January 9, 2026
• First Posted (Actual): January 16, 2026

Study Record Updates

• Last Update Posted (Actual): February 3, 2026
• Last Update Submitted That Met QC Criteria: February 2, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: nutritional status; obesity; long-term follow-up; sleeve gastrectomy; anthropometric measurements; metabolic outcomes
• 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-02

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared due to the need to protect patient privacy and confidentiality. T

Drug and device information, study documents

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