OBJECTIVE Premorbid obesity is an identified risk factor for eating disorder (ED) development among adolescent males. However, pervasive gender- and weight-related biases about ED inhibit timely diagnosis and treatment among this demographic. This study examined the psychological and medical characteristics of three adolescent males with premorbid obesity who were not diagnosed with atypical anorexia nervosa (AAN) until medical sequelae of malnutrition warranted emergent hospitalization. Factors associated with diagnostic delays among these cases were identified to facilitate increased awareness of this at-risk demographic. METHODS Retrospective chart review was conducted on three adolescent males (aged 12-17) with AAN and premorbid obesity who were medically hospitalized for 13-24 days (M = 20.3, SD = 9.7). Demographic variables, psychological characteristics, and physical data were extracted. RESULTS Each case presented at normal or overweight BMI status (M = 22.7 kg/m2, SD = 3.2) following a significant loss of weight ranging from 19 to 42% of total body mass (M = 31.7%, SD = 9.5) over 5-12 months (M = 8.3, SD = 2.9). Plausible factors associated with diagnostic delays included initial weight loss recommendations by a medical provider, with little support or oversight; limited insight that symptoms were problematic; social reinforcement of dieting behaviors; low prevalence of psychiatric comorbidity; parental obesity; and parental history of bariatric surgery. CONCLUSIONS These cases elucidate the importance of close follow-up of youth with obesity who are encouraged to lose weight. Further education about AAN among males with premorbid obesity is crucial for timely diagnosis and intervention.