To investigate retrospectively the orthognathic surgery (OGS) patients experience in weight loss and the influence of gender, age, duration of the surgical procedure, length of hospital stay, location of surgery and use of intermaxillary fixation (IMF) or without IMF on postoperative weight loss. A total of 4487 patients treated by OGS where all patients visited the outpatient clinic one, three and six weeks after the surgical procedure. After six weeks, patients filled out a questionnaire in which weight loss was addressed. The patients were asked to give an estimate of their experiences weight loss. The population was first divided in two groups weight loss and no weight loss. In the weight loss group there is no significant difference in weight loss between patients with IMF and patients without IMF. In the weight loss group there were significantly more females then males. Further, in the subgroup IMF the operation time was significantly longer compared with the subgroup without IMF. The other parameters including age and hospital stay were not different in the groups. IMF in orthognathic treatment does not result in a difference self-reported loss of body weight compared to patients without IMF. Treatment protocols should include pre- and post-operative dietician consultations and possible indications for medical nutrition and vitamins.