Background: Considering the result of animal studies regarding the effect of Elaeagnus angustifolia (EA) on weight, the present study was designed to assess the effect of whole fruit and medulla of EA powder supplementation on weight and dietary intake of patients with knee osteoarthritis (OA). Methods: In this interventional study, 90 female patients with OA were allocated into whole fruit powder of EA (15 g/d), medulla powder of EA (15 g/d), and placebo groups. The supplementation duration was eight weeks. The weight and height were measured using the standard protocol, and the body mass index (BMI) was calculated. The dietary intake was assessed using the 24-hour recall for three days and analyzed using Nutritionist IV software. Then, paired t-tests and analysis of variance (ANOVA) were used as a statistical analysis. Results: A total of 78 patients participated in this study. The mean age of participants was 56.31±8.55 years, and the mean BMI was 32.44±2.95 kg/m2 . None of the participants were physically active, 69% of them were inactive, and 31% were minimally active. There were no significant differences between groups regarding the baseline values. The mean BMI decreased in the EA medulla and whole fruit group, and it increased in the placebo group. However, the changes were not significant in the studied groups (P>0.05). The results of within-group analyses indicated no significant changes in energy, macronutrients, and antioxidant micronutrient intake after EA medulla, whole fruit, and placebo supplementation compared with baseline values (P>0.05). The result of between-group analyses also showed no significant difference between groups regarding the changes in energy, macro, and micronutrient intake. Conclusion: The results of the present clinical trial indicated that EA has no significant effect on anthropometric characteristics and dietary intake in patients with OA.