Ketogenic Dietary Intervention in Men With Mild-to-Moderate COPD

Chronic obstructive pulmonary disease (COPD) is associated with persistent airflow limitation, systemic inflammation, reduced exercise capacity, and unfavorable changes in body composition. Nutritional interventions may represent a complementary strategy to improve clinical outcomes in individuals with COPD. This pilot randomized controlled trial evaluates the feasibility, safety, and preliminary effectiveness of an 8-week ketogenic dietary intervention in men with mild-to-moderate COPD. Participants are randomly assigned to either a supervised ketogenic diet or a control group receiving standard dietary advice. The ketogenic diet restricts carbohydrate intake and promotes nutritional ketosis, which is monitored using blood beta-hydroxybutyrate measurements. The primary outcome is change in the FEV1/FVC ratio. Secondary outcomes include systemic inflammation assessed by C-reactive protein (CRP), phase angle measured by bioelectrical impedance analysis, functional exercise capacity assessed by the 6-minute walk test, estimated aerobic capacity, body composition, and selected biochemical safety markers. The study aims to provide preliminary evidence regarding whether a ketogenic dietary approach may improve inflammatory status, functional capacity, and physiological outcomes in individuals with COPD.

Inclusion Criteria: * Male sex * Age between 40 and 75 years * Clinically stable chronic obstructive pulmonary disease (COPD) * GOLD stage I or II COPD * No acute COPD exacerbation within the previous 3 months * Stable pharmacological treatment for at least 4 weeks before enrollment * Ability to complete study assessments and comply with dietary instructions * Provision of written informed consent Exclusion Criteria: * GOLD stage III or IV COPD * Uncontrolled cardiovascular disease * Chronic kidney disease * Severe hepatic dysfunction * Active malignancy * Insulin-dependent diabetes mellitus * Participation in another dietary intervention program within the previous 3 months * Inability to complete study assessments * Contraindications to dietary carbohydrate restriction * Refusal or inability to provide informed consent