Caelius Aurelianus (5th century AD) is famous for translating the writings of Soranus of Ephesus (2nd century AD) into Latin. In his book On acute and chronic diseases, Caelius gives an almost complete edition of the works of Soranus, while adding some of his own and other writers' material. Obesity was even at that time considered to be a disease and the authors treat the subject extensively. The nature, etiology, the clinical manifestations of obesity are described, although treatment covers the greatest part of the material. Infliction of perspiration, very low caloric intake diet, exercise, and diuresis are proposed, and one cannot overlook the strong similarities of some of the treatments with those used nowadays as secondary aids for weight loss.