Interventions for Weight Regain After Bariatric Surgery

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.

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

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

Sponsors & Collaborators

• Medipol University

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

45 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-05-12

Primary Completion

2025-07-10

Completion

2025-07-10

Countries

• Turkey (Türkiye)

Study Locations