Background:Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Malnutrition and weight loss are common in COPD patients and are associated with poor prognosis .Objectives:To study the relationship between the severity of COPD and body mass index (BMI), and to ascertain the correlation between BMI and the FEV1 decline rate and severity of the disease.Methods: This cross-sectional study included 209 COPD patients. Patients were classified according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) staging system. BMI was calculated and patients were categorized as underweight, normal weight, overweight, or obese. Results:The classification of patients according to the severity of airflow limitation revealed that 10 patients were classified as having mild airflow limitation, 89 patients had moderate airflow limitation, 102 patients had severe airflow limitation, and 8 patients had very severe airflow limitation. It was observed that the patients' BMI decreased asthe disease severity increased (GOLD), and this relationship was statistically significant (P < 0.05). In the study populations with greater post-FEV1% projected values, the BMI was better. Conclusion:The findings support the concept of the "obesity paradox" in COPD patients, where obesity is associated with better outcomes. Low BMI was positively associated with the increased severity of obstruction in COPD patients. Malnutrition and weight loss are serious ailments, which ought to be taken carefully while addressing COPD patients. Active dietary supplements offer likelihood to increase body weight while also enhancing exercise tolerance and respiratory health, thereby decreasing morbidity and mortality.