Abstract
Weight loss is not uncommon in the field of psychiatry; however, when severe cases arise, it necessitates attention and thorough evaluation for accurate diagnosis and appropriate treatment. This report highlights the case of a 32-year-old man referred to psychiatry due to significant weight loss. The patient mentioned consuming small food portions, attributing it to an undetected stomach illness despite repeated investigations by previous treating doctors. His current weight stood at 31 kg, with a body mass index (BMI) of 10.2 kg/m². Physical examinations and laboratory investigations were otherwise within normal parameters. A somatic delusion was confirmed, and the patient has been diagnosed with a delusional disorder after excluding other possibilities. This report highlights the importance of considering delusional disorder (somatic type) as a potential diagnosis for substantial weight loss, and it records an unexpected degree of physical well-being despite a notably low BMI.