title: Body mass index and the risk of infection - from underweight to obesity.
abstract: BACKGROUND
  Nutritional status is a well-known risk factor for metabolic and endocrine disorders. Recent studies suggest that dietary intake also affects immune function and as a consequence infection risk.
  
  
  OBJECTIVE
  This reviews aims to give an overview on the effect of body weight on infection rate at different periods of life.
  
  
  METHODS
  Clinically relevant prospective, cross-sectional and case-control community-based studies are summarized.
  
  
  BACKGROUND
  In children and adolescents underweight is a significant risk factor for infection especially in developing countries, probably reflecting malnutrition and poor hygienic standards. Data from industrialized countries suggest that infection rate is also increased in obese children and adolescents. Similarly, several studies suggest a U-shaped increased infection rate in both underweight and obese adults. In the latter, infections of the skin and respiratory tract as well as surgical-site infections have consistently been reported to be more common than in normal-weight participants. Paradoxically, mortality of critically ill patients was reduced in obesity in some studies.
  
  
  CONCLUSIONS
  Several studies in children or adults suggest that both underweight and obesity are associated with increased infection risk. However, confounding factors such as malnutrition, hygienic status and underlying disease or co-morbidities might aggravate accurate assessment of the impact of body weight on infection risk.
authors.affiliation: Christian Doppler Laboratory for Metabolic Research, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Dobner
authors.affiliation: Christian Doppler Laboratory for Metabolic Research, Medical University Innsbruck, Innsbruck, Austria; Department of Internal Medicine 1, Medical University Innsbruck, Austria. Electronic address: susanne.kaser@i-med.ac.at.
authors.forename: S
authors.initials: S
authors.lastname: Kaser
mesh_terms: D000293:Adolescent; D000328:Adult; D001424:Bacterial Infections / Q000276:immunology*; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D004198:Disease Susceptibility / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D009181:Mycoses / Q000276:immunology*; D009752:Nutritional Status; D009765:Obesity / Q000276:immunology*; D012307:Risk Factors; D013851:Thinness / Q000276:immunology*
keywords: Anorexia nervosa; Body mass index; Infection risk; Obesity; Underweight