The Effect of a Balanced Low-Calorie Diet on Depression Score in Overweight and Obese Patients: A Quasi-Experimental Study

Background: Obesity and depression are interrelated public health concerns with significant physical and psychological consequences. This study aimed to evaluate the effect of a balanced low-calorie diet on depression scores in overweight and obese individuals. Methods: In this 12-week quasi-experimental trial, 78 overweight and obese adults (BMI 25–39.9 kg/m²) with Beck Depression Inventory (BDI) scores >13 were enrolled in Larestan, Iran. Participants received a personalized low-calorie diet (500 kcal/day deficit based on Harris-Benedict equation). Moreover, anthropometric measurements and BDI scores were assessed at baseline and after the intervention. Statistical analysis included paired t-tests and multivariate regression, adjusting for age, sex, and baseline depression scores. Results: Sixty-seven participants (15 men, 52 women, mean age 36.4±10.0 years) completed the study. Significant reductions were observed in weight, BMI, waist circumference, and BDI scores (all P<0.001). After adjustment, a one-unit decrease in BMI predicted a 1.19-point reduction in BDI score (P=0.011), and a one-centimeter decrease in waist circumference predicted a 0.18-point reduction (P=0.039). Conclusions: A balanced low-calorie diet significantly reduced both depression scores and anthropometric indices in overweight and obese patients. Thus, dietary intervention may serve as a cost-effective, adjunctive strategy for managing depression levels in this population.