Micronutrient and vitamin deficiencies in young adults in the United States are relatively rare and often pose a diagnostic challenge. Here, we present the case of a young female who developed acute encephalopathy and muscular weakness two days following an endoscopic procedure performed to investigate the patient’s four-month history of intractable nausea, vomiting, dysphagia, and weight loss. She was diagnosed with severe Wernicke encephalopathy due to thiamine deficiency as well as myotonic dystrophy type 1 (DM1). The patient’s family history revealed an undiagnosed muscular disorder that required her father to ambulate with a wheelchair in the fourth decade of his life. DM1 with 11 trinucleotide repeats of cytosine-thymine-guanine in allele 1 and more than 150 in allele 2 of the myotonic dystrophy protein kinase ( DMPK ) gene were found on genetic testing. The patient’s progressive dysphagia was likely a chronic manifestation of myotonic dystrophy that became more apparent following general anesthesia. DM1 is a multisystem genetic disorder of both skeletal and smooth muscles caused by deviation in the DMPK gene. Due to the involvement of esophageal smooth muscle, dysphagia may also be present. The long-standing dysphagia in our patient resulted in significant vitamin deficiency presenting as Wernicke encephalopathy. This case highlights the need for detailed, accurate family history and heightened suspicion for malnutrition in young adults who have eating disorders, dysphagia, and unexplained neurological changes.