Objective To explore longitudinal changes in nutrition impact symptoms NIS among head and neck cancer HNC patients at different stages of radiotherapy RT and further analyze the impact of NIS on weight. Method A total of 123 HNC patients were investigated in the first week third week fifth week and seventh week of RT. Generalized Estimation Equation GEE was used to estimate the impact of NIS interference scores on weight. Result During the first week third week fifth week and seventh week of radiotherapy the numbers of NIS interfering with diet were 2 1 3 5 3 7 6 5 7 6 5 8 and the total interference scores were 19. 70±2. 47 24. 63±4. 47 27. 59±4. 71 28. 56±5. 13 and the mean body weights were 62. 06±9. 87 kg 61. 73±10. 2 kg 59. 79± 9. 67 kg 58. 3±9. 42 kg respectively each showing significant differences over time P<0. 001 . NIS of pain lack of energy and taste change impacted weight reduction P<0. 05 . Conclusion The number incidence and severity of NIS that interfere with diet in patients with HNC aggravate as RT progresses. NIS of pain lack of energy and taste change had significant impacts on weight loss. Medical staff should develop a holistic symptom management plan and dietary guidance program to strengthen the evaluation of effects.