title: Weight loss interventions in asthma: EAACI evidence-based clinical practice guideline (part I).
abstract: BACKGROUND
  Asthma and obesity are chronic multifactorial conditions that are associated with gene-environment interaction and immune function. Although the data are not fully consistent, it seems that obesity increases the risk of asthma and compromises asthma control.
  
  
  OBJECTIVE
  To investigate the impact that weight changes have on asthma.
  
  
  METHODS
  We carried out a systematic review of three large biomedical databases. Studies were scrutinized and critically appraised according to agreed exclusion and inclusion criteria. Quality assessment of eligible papers was conducted using the GRADE method. Meta-analyses of comparable studies were carried out.
  
  
  RESULTS
  Thirty studies met the eligibility criteria of the review. Interventions were limited to dietary manipulation in three studies, one of which also used anti-obesity drugs, and bariatric surgery in four. All the other studies reported observational data. Becoming obese increased the odds for incident asthma by 1.82 (95% CI 1.47, 2.25) in adults and 1.98 (95% CI 0.71, 5.52) in children. Weight loss was associated with significant improvement in mean scores for symptoms, rescue medication score, and asthma exacerbations in the only randomized controlled trial. Similarly, evidence gathered from observational studies, with follow-up ranging between 8 weeks to 1 year, and from changes 1 year after bariatric surgery showed improvements in all asthma control-related outcomes. Changes in lung function were reported in one randomized controlled and eight observational studies of asthmatic subjects, with conflicting results. Either improvement after weight loss, decline with weight gain, or no effects at all were reported. Changes in airway inflammation and responsiveness were reported only by observational studies.
  
  
  CONCLUSIONS
  Weight increases above the obesity threshold significantly increase the risk of asthma. The available studies show weak evidence of benefits from weight reduction on asthma outcomes.
authors: Faculty of Medicine, University of Porto and Hospital São João, Porto, Portugal. andremoreira@med.up.pt
authors: A
authors: A
authors: Moreira
authors: M
authors: M
authors: Bonini
authors: V
authors: V
authors: Garcia-Larsen
authors: S
authors: S
authors: Bonini
authors: S R
authors: SR
authors: Del Giacco
authors: I
authors: I
authors: Agache
authors: J
authors: J
authors: Fonseca
authors: N G
authors: NG
authors: Papadopoulos
authors: K H
authors: KH
authors: Carlsen
authors: L
authors: L
authors: Delgado
authors: T
authors: T
authors: Haahtela
mesh_terms: D001249:Asthma / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D019317:Evidence-Based Medicine; D006801:Humans; D015994:Incidence; D009765:Obesity / Q000150:complications; D015431:Weight Loss