Patients with head and neck cancer (HNC) are at risk for undernutrition. Dietary counseling during treatment has positive effects on nutritional status and quality of life, however, the effects of dietary counseling started before initiation of treatment are currently unknown. Therefore we assessed the effect of early individualized dietary counseling (DC) on weight loss, major complications, and length of hospital stay (LOS) in patients with HNC. Ninety-five newly diagnosed HNC patients with (risk of) undernutrition receiving DC were compared to 95 matched HNC patients receiving usual nutritional care (UC). Difference in weight change over time was analyzed by generalized estimating equations (GEE). Differences in complications and LOS were studied by Pearson chi-squared and student's t-tests. Weight change between diagnosis and end of treatment was -6.0 ± 6.9% (DC) and -5.4 ± 5.7% (UC; GEE: -0.4kg, 95% confidence interval: -1.2 to 0.5; P = 0.44). Less DC patients experienced overall postoperative complications (44%/70%, P = 0.04). No effect on major postoperative or (chemo)radiotherapy complications or LOS was found. This study showed a lower prevalence of overall postoperative complications in HNC patients receiving DC but could not demonstrate an effect on weight loss, other complications, and LOS.