KOBE Study: Adherence to and Tolerability of Different Very-low-calorie Ketogenic Protocols (VLCKD, Very Low-Calorie Ketogenic Diet) in Patients With Obesity and Complicated Overweight.
Conditions: Obesity & Overweight, MASLD/MASH (Metabolic Dysfunction-Associated Steatotic Liver Disease / Metabolic Dysfunction-Associated Steatohepatitis), Type 2 Diabetes, Insulin Resistance
Sponsor: University of Bologna

Study Protocol and Statistical Analysis Plan 
Official Title: KOBE Study: Adherence and Tolerability of Different Very Low-Calorie Ketogenic 
Diet (VLCKD) Protocols in Adults With Obesity or Complicated Overweight 
 
NCT Number: Not yet assigned 
Document Type: Study Protocol and Statistical Analysis Plan 
Version: 2.0 – PRS formatted 
Document Date: 29 July 2021 
Sponsor / Coordinating Center: University of Bologna – Policlinico Sant’Orsola-Malpighi 

1. Background and Rationale 
Very low-calorie ketogenic diets (VLCKD) are medically supervised dietary interventions 
characterized by a marked reduction in caloric and carbohydrate intake, inducing a state of 
nutritional ketosis. These diets are increasingly used in the management of obesity and 
obesity-related metabolic conditions, including type 2 diabetes mellitus and non-alcoholic fatty liver 
disease. Although VLCKD protocols are widely applied in clinical practice, they differ substantially in 
terms of protein sources, including natural foods, protein supplements, and commercially available 
meal replacements. The KOBE Study was designed to collect real-world data from routine clinical 
practice in order to compare different VLCKD protocols and generate evidence to support informed 
clinical decision-making. 
 
 
2. Study Objectives 
Primary Objective: To compare four VLCKD protocols with respect to dietary adherence, 
occurrence of adverse effects, dropout rate, and patient-reported satisfaction with the diet. 
 
Secondary Objectives: To evaluate changes in anthropometric parameters, body composition, 
biochemical and metabolic parameters, and liver steatosis and fibrosis assessed by ultrasound and 
transient elastography. 
 
 
3. Study Design 
This is a single-center, prospective, observational study conducted within routine clinical care at a 
hospital-based clinical nutrition service. Participants are not randomized and select the VLCKD 
protocol according to personal preference after standardized counseling. 
 
 
4. Study Population 
Inclusion Criteria: Adults with obesity (BMI  30 kg/m²) or overweight (BMI 25.0–29.9 kg/m²) with 
non-alcoholic fatty liver disease and a previous unsuccessful hypocaloric diet. 
 
Exclusion Criteria: Age < 18 years, pregnancy or breastfeeding, moderate to severe renal 
insufficiency, significant cardiovascular disease, severe liver disease, type 1 diabetes mellitus or 
advanced type 2 diabetes, eating disorders, major psychiatric conditions, or frail elderly status. 
 
 
5. Observational Groups 
All VLCKD protocols consist of three phases (ketogenic phase, reintroduction phase, maintenance 
phase). The four observational groups differ only in the protein sources used during the ketogenic 
phase. 
 
 
6. Study Procedures and Assessments 
Participants undergo scheduled medical and dietary visits as part of routine clinical care. Collected 
data include anthropometric measurements, body composition analysis by bioelectrical impedance, 
laboratory tests, liver ultrasound and transient elastography, capillary blood ketone monitoring, and 
validated patient-reported outcome questionnaires. 

7. Study Duration and Follow-Up 
The active dietary intervention lasts approximately 26 weeks, with an additional follow-up visit 
approximately three months after completion. 
 
 
8. Statistical Analysis Plan 
Sample Size: A minimum of 21 participants per observational group is planned, with a total sample 
size ranging from 84 to 200 participants. 
 
Statistical Methods: Descriptive and comparative analyses using parametric or non-parametric 
methods. Propensity score methods will be applied to account for the non-randomized design. 
 
 
9. Ethical Considerations 
The study is conducted in accordance with the Declaration of Helsinki and Good Clinical Practice 
principles. Written informed consent is obtained from all participants prior to data collection. 
 
 
10. Data Management and Confidentiality 
Study data are collected using a secure electronic data capture system. Participant confidentiality is 
maintained through coded identifiers. 
 
 
11. Dissemination of Results 
Study results will be made publicly available through ClinicalTrials.gov and may be published in 
peer-reviewed scientific journals.