title: Leptin and smoking cessation: secondary analyses of a randomized controlled trial assessing physical activity as an aid for smoking cessation.
abstract: BACKGROUND
  Smokers have a lower body weight compared to non-smokers. Smoking cessation is associated with weight gain in most cases. A hormonal mechanism of action might be implicated in weight variations related to smoking, and leptin might be implicated. We made secondary analyses of an RCT, with a hypothesis-free exploratory approach to study the dynamic of leptin following smoking cessation.
  
  
  METHODS
  We measured serum leptin levels among 271 sedentary smokers willing to quit who participated in a randomized controlled trial assessing a 9-week moderate-intensity physical activity intervention as an aid for smoking cessation. We adjusted leptin for body fat levels. We performed linear regressions to test for an association between leptin levels and the study group over time.
  
  
  RESULTS
  One year after smoking cessation, the mean serum leptin change was +3.23 mg/l (SD 4.89) in the control group and +1.25 mg/l (SD 4.86) in the intervention group (p of the difference < 0.05). When adjusted for body fat levels, leptin was higher in the control group than in the intervention group (p of the difference < 0.01). The mean weight gain was +2.91 (SD 6.66) Kg in the intervention and +3.33 (SD 4.47) Kg in the control groups, respectively (p not significant).
  
  
  CONCLUSIONS
  Serum leptin levels significantly increased after smoking cessation, in spite of substantial weight gain. The leptin dynamic might be different in chronic tobacco users who quit smoking, and physical activity might impact the dynamic of leptin in such a situation. Clinical trial registration number: NCT00521391.
authors.affiliation: Department of Epidemiology and Biostatistics, University of California San Francisco, 1450 3rd Street, San Francisco, CA, USA. semira.gonseth@gmail.com.
authors.forename: Semira
authors.initials: S
authors.lastname: Gonseth
authors.forename: Isabella
authors.initials: I
authors.lastname: Locatelli
authors.forename: Raphaël
authors.initials: R
authors.lastname: Bize
authors.forename: Sébastien
authors.initials: S
authors.lastname: Nusslé
authors.forename: Carole
authors.initials: C
authors.lastname: Clair
authors.forename: François
authors.initials: F
authors.lastname: Pralong
authors.forename: Jacques
authors.initials: J
authors.lastname: Cornuz
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001835:Body Weight / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D012107:Research Design; D016540:Smoking Cessation / Q000379:methods* / Q000706:statistics & numerical data*; D015430:Weight Gain / Q000502:physiology
chemical_list: D015415:Biomarkers; D020738:Leptin