Objective To understand the lived experience of patients undergoing bariatric and metabolic surgery when using generative artificial intelligence tools to acquire weight loss information, and to explore the related driving factors and barriers, thereby providing a reference for developing generative AI-based weight loss information platforms for this population. Methods A descriptive qualitative study was conducted. From October 2024 to April 2025, semi-structured interviews were carried out with 16 patients with obesity who had undergone bariatric and metabolic surgery. Thematic analysis was used for data analysis and theme extraction. Results Four main themes were identified: supporting and actively exploring generative AI; generative AI assisting in decision-making; generative AI contributing to the improvement of patient health literacy; and practical issues and challenges in the application of generative AI. Conclusion Generative AI plays a positive role in assisting health-related decisions-making, providing dietary guidance, and promoting healthy eating behaviors. However, barriers to its use by patients undergoing bariatric and metabolic surgery include ethical and safety concerns, a lack of empathy, and insufficient professional supervision. Future efforts should focus on developing safe, effective, and patient-centered generative AI weight loss information platforms to meet the needs of these patients.