To investigate the effect of a 5:2 intermittent fasting diet with high protein content versus daily calorie restriction balanced diet on anthropometric indices, body composition analysis, functional status, pain intensity, and serum markers of inflammation and oxidative stress in overweight and obese postmenopausal women with knee osteoarthritis

To determine the effect of a 5:2 intermittent fasting diet with high protein content compared to a balanced diet with daily calorie restriction on anthropometric indices, body composition analysis, functional status, pain intensity, and serum markers of inflammation and oxidative stress in overweight and obese postmenopausal women with knee osteoarthritis.

Controlled clinical trial, with parallel groups, single-blind, randomized, phase 3 on 150 patients

The patients will be selected from among female patients referred to the Physical Medicine Clinic of Imam Reza Hospital in Tabriz with a diagnosis of knee osteoarthritis using a convenience sampling method and will be randomly assigned to receive two balanced low-calorie diets and a 5:2 intermittent fasting diet for 4 months.

Inclusion criteria: Diagnosis of knee osteoarthritis by a physical medicine specialist Stopping the menstrual cycle naturally 12 months ago Body mass index of 25 kg/m2 and above Not having another inflammatory disease, such as rheumatoid arthritis No intra-articular injection for the past 3 months No oral medication (nonsteroidal anti-inflammatory drugs) for one week before study entry. Exclusion criteria: Daily calorie intake of less than 800 and more than 4200 kcal A deviation from a specific eating pattern due to medical or other reasons Use of dietary supplements, diuretics, or laxatives during the intervention period Participation in sports programs or changes in physical activity Failure to follow the recommended diet Use of weight-affecting medications

Intervention group: 5:2 intermittent fasting diet with high protein content Control group: Balanced low-calorie diet

Anthropometric indices, body composition, functional status, pain level, serum markers of inflammation, and oxidative stress

We will use a stratified block randomization method for allocation. The computer-generated code, created using SAS software version 8.01, will be used to create a randomized sequence by a statistician outside the project's research team. Randomization will be stratified based on body mass index and osteoarthritis severity (mild, moderate, and severe). Serially numbered, opaque, sealed packets will be used to ensure allocation

Blinding the patients is not feasible in this trial. A trained nutritionist will ban diet-related conversations between assessors and patients during the study. Outcome assessors and the person responsible for statistical analysis will be blinded to the type of interventions received until the end of the study