Background Nutritional counseling is frequently overlooked in cancer patients with normal nutritional status. This study aimed to evaluate the impact of nutritional counseling in head and neck cancer (HNC) patients with normal nutritional status prior to concurrent chemoradiotherapy (CCRT). Methods A total of 243 patients with pretreatment normal nutritional status and locally advanced HNC receiving concurrent chemoradiotherapy (CCRT) at three medical centers were enrolled. All patients were retrospectively allocated into the early (≤ 2 weeks, n = 105, 43.2%), late (> 2 weeks, n = 102, 42.0%), and no nutritional counseling groups ( n = 36, 14.8%) according to the time interval between the date of CCRT initiation and the first date of nutritional counseling for comparison. Results The 1-year overall survival rates were 95.0%, 87.5%, and 81.3% in the early, late, and no nutritional counseling groups ( p = 0.035), respectively. The median body weight changes at end of CCRT were − 4.8% (range, − 13.3 to 8.7%), − 5.6% (range, − 21.9 to 5.6%), and − 8.6% (range, − 20.3 to 2.4%) in patients in the early, late, and no nutritional counseling groups, respectively. The early termination of chemotherapy rates and the incompletion rates of planned radiotherapy were 1.9% and 1.9%, 2.9%, and 2.0%, 13.9%, and 19.4% in patients in the early, late, and no nutritional counseling groups, respectively. Conclusions Our findings strongly suggest that while some HNC patients may have pretreatment normal nutritional status, early nutritional counseling is nevertheless essential for the improvement of treatment tolerance and survival outcome.