A 54‐years‐old woman complained of unintentional important body weight gain associated with abdominal bloating. For this reason, she had consulted many different diet and nutritional professionals, general practitioners and a gastroenterology specialist, but no one went beyond a simple diagnosis of “monstrous obesity”. At our hospital division, based on physical examination, a computed tomography (CT) of the abdomen and pelvis was performed. It showed a voluminous intraperitoneal mass occupying the most part of the abdomen. The patient underwent laparotomy with resection of the abdomino‐pelvic mass, originating from the left ovary, measuring 60 x 45 cm and weighing 46 kg. Histopathology examination revealed a tumor composed of three different areas, including a well‐differentiated adenocarcinoma of intestinal‐type. It is emblematic of a grotesque misdiagnosis generated by a non‐comprehensive patient assessment and consequently by a too quick judgement related to the "anti‐fat bias".