NCT06963437

Interventions for Weight Regain After Bariatric Surgery

Comparison of Revisional Surgery, Ketogenic Diet, and Intermittent Fasting in Bariatric Surgery Patients With Weight Regain: A Prospective Randomized Controlled Study

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 43 (actual)
• Sponsor: Medipol University · Academic / Other
• Sex: All
• Age: 18 Years – 45 Years
• Healthy volunteers: Not accepted

Summary

Study Objective: The aim of this study is to evaluate the effects of revisional bariatric surgery (RBS), very low-calorie ketogenic diet (VLCKD), and intermittent fasting (IF) on nutritional habits and clinical outcomes (anthropometric and biochemical measurements) in patients with insufficient weight loss (IWL) or weight regain (WR) after bariatric surgery, and to compare these findings with those of a control group.

Detailed description

Study Hypotheses: 1. In patients with IWL or WR after bariatric surgery, a diet following the bariatric care guidelines (BCGs) after revisional bariatric surgery (RBS) improves nutritional habits, anthropometric, and biochemical parameters. 2. In patients with IWL or WR after bariatric surgery, VLCKD improves nutritional habits, anthropometric, and biochemical parameters. 3. In patients with IWL or WR after bariatric surgery, IF regimen improves nutritional habits, anthropometric, and biochemical parameters. 4. In patients with IWL or WR after bariatric surgery, the diet program recommended by the ASMBS as part of standard post-bariatric care improves nutritional habits, anthropometric measurements, and biochemical parameters.

Conditions

• Obese Patients With Bariatric Surgery
• Obese Patients (BMI ≥ 30 kg/m²)
• Weight Regain Post Bariatric Surgery
• Revisional Bariatric Surgery
• Ketogenic Dieting
• Intermittent Fasting

Interventions

Type	Name	Description
OTHER	Diet	A four-stage dietary program will be implemented in accordance with ASMBS guidelines. To the best of our knowledge, there is currently no study comparing the dietary approach following revisional bariatric surgery with ketogenic and intermittent fasting diets
OTHER	Ketogenic diet	A high-protein Very Low-Calorie Ketogenic Diet (VLCKD) will be implemented as the nutritional intervention. In line with previous studies, the daily energy intake of the ketogenic diet will be planned as 600-800 kcal, with approximately 10% of energy from carbohydrates (\<30 g/day), 40-45% from protein, and 40-50% from fat. Total carbohydrate intake will be restricted to less than 30 g per day, primarily from vegetables, while fat intake will derive from natural protein sources and 10 g of olive oil per day.
OTHER	Fasting	Patients in this group will follow a time-restricted eating pattern (16/8) for a duration of 6 weeks, with food intake limited to an 8-hour window each day. Intermittent fasting will preferably be observed between 6:00 PM and 10:00 AM; however, patients may choose alternative 16-hour fasting periods such as 7:00 PM-11:00 AM or 8:00 PM-12:00 PM, depending on their individual routines. During the 8-hour feeding window, patients will adhere to the stage 4 post-bariatric dietary guidelines in accordance with ASMBS recommendations
OTHER	Control	No individualized diet will be planned

Timeline

• Start date: 2025-05-12
• Primary completion: 2025-07-10
• Completion: 2025-07-10
• First posted: 2025-05-09
• Last updated: 2025-08-01

Locations

2 sites across 1 country: Turkey (Türkiye)