Although several studies have reported that poor nutritional status is associated with a worse prognosis in patients with interstitial lung disease (ILD), the beneficial impact of nutritional therapy has not yet been established. We report a case of idiopathic pulmonary fibrosis (IPF) in which nutritional therapy played an important role alongside drug therapy. A 71-year-old Japanese male was diagnosed with IPF and started on nintedanib. However, he experienced appetite loss, leading to significant weight loss and disease progression. Consequently, nintedanib was discontinued, and a dietitian introduced a high-fat, high-protein nutritional therapy. His condition improved, allowing nintedanib to be restarted after a period of cessation. Following multiple nutritional education sessions, his condition stabilized without further appetite loss. These findings suggest that when determining treatment strategies for patients with ILD, clinicians should incorporate appropriate nutritional management during long-term treatment with effective anti-ILD agents to optimize patient outcomes.