title: The obesity paradox in the surgical population.
abstract: BACKGROUND
  Despite the medical hazards of obesity, recent reports examining body mass index (BMI) show an inverse relationship with morbidity and mortality in the surgical patient. This phenomenon is known as the 'obesity paradox'. The aim of this review is to summarize both the literature concerned with the obesity paradox in the surgical setting, as well as the theories explaining its causation.
  
  
  METHODS
  PubMed was searched to identify available literature. Search criteria included obesity paradox and BMI paradox, and studies in which BMI was used as a measure of body fat were potentially eligible for inclusion in this review.
  
  
  RESULTS
  The obesity paradox has been demonstrated in cardiac and in non-cardiac surgery patients. Underweight and morbidly obese patients displayed the worse outcomes, both postoperatively as well as at long-term follow-up. Hypotheses to explain the obesity paradox include increased lean body mass, (protective) peripheral body fat, reduced inflammatory response, genetics and a decline in cardiovascular disease risk factors, but probably unknown factors contribute too.
  
  
  CONCLUSIONS
  Patients at the extremes of BMI, both the underweight and the morbid obese, seem to have the highest postoperative morbidity and mortality hazard, which even persists at long-term. The cause of the obesity paradox is probably multi-factorial. This offers potential for future research in order to improve outcomes for persons on both sides of the 'optimum BMI'.
authors.affiliation: Department of Anesthesiology, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Tabita M
authors.initials: TM
authors.lastname: Valentijn
authors.forename: Wael
authors.initials: W
authors.lastname: Galal
authors.forename: Elke K M
authors.initials: EK
authors.lastname: Tjeertes
authors.forename: Sanne E
authors.initials: SE
authors.lastname: Hoeks
authors.forename: Hence J
authors.initials: HJ
authors.lastname: Verhagen
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Stolker
mesh_terms: D015992:Body Mass Index; D015897:Comorbidity; D014943:Global Health; D006801:Humans; D009017:Morbidity / Q000639:trends; D009767:Obesity, Morbid / Q000453:epidemiology*; D012307:Risk Factors; D013514:Surgical Procedures, Operative; D015996:Survival Rate / Q000639:trends