This study aimed to examine the characteristics of psychiatrists and the hospital settings in relation to the first-time diagnoses of anorexia nervosa (AN) and bulimia nervosa (BN) and depict medical utilization and the detection rate before diagnosis of patients with AN and BN. We extracted data of individuals with AN or BN, as defined by the International Classification of Diseases, Ninth Revision, Clinical Modification, from a national health insurance database. Individuals with AN (n = 1,893) or BN (n = 10,542) who were first-time diagnosed by psychiatrists from 2002 to 2013 were included. Individuals with schizophrenia were selected as control groups that were matched with the incident AN and BN cases for sex, age stratum, and year of diagnosis. AN was more likely to be diagnosed by female psychiatrists. Patients with AN were more frequently diagnosed in medical centers while patients with BN were mostly diagnosed in primary care clinics. Nearly all patients with AN and BN had sought treatment for physical problems but less than half had sought help for mental health problems in the year preceding the diagnosis. Individuals with AN, BN, and schizophrenia were all under-detected by nonpsychiatric medical professionals. Notably, BN was least likely to be recognized by both psychiatrists and other medical professionals. Our findings underscore the importance of educational programs that are designed to improve the detection and management of eating disorders by medical professionals in Taiwan. Advanced educational programs that target differential diagnosis and the tailored management of different eating disorders should be highlighted among psychiatrists.