Objective: During the COVID-19 pandemic, our diet and lifestyle have changed significantly. In this study, it was aimed to determine the changes in diet, body weight and Orthorexia Nervosa (ON) tendency in the pandemic. Method: This cross-sectional study was carried out among adults (n 1/4 945). An online questionnaire was used to determine nutrition, lifestyle factors and ON tendency (via Google Docs). The questionnaire was also shared on social media groups and pages (instagram, twitter and facebook) managed by registered dietitians. Results: During the COVID-19 pandemic individuals' body weight and total food consumption increased by 51.0% and 57.2%, respectively. Increased screen time (OR: 1.912, 95% CI: 1.374-2.661 p < 0.001), sleeping time (OR: 3.630, 95% CI: 2.551-5.166 p < 0.001) and decreased physical activity (OR: 2.051, 95% CI: 1.198-3.509 p < 0.01) were associated with weight gain. The ON tendency increased in all groups according to the change in food consumption status (p < 0.05). Conclusions: Considering the ongoing pandemic, individuals should be provided with adequate nutri-tional support. It is very important to get that support from nutritionists in order to monitor and control body weight and ON tendency. (C) 2022 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.