title: The enigma of increased non-cancer mortality after weight loss in healthy men who are overweight or obese.
abstract: OBJECTIVE
  To study effects on non-cancer mortality of observational weight loss in middle-aged men stratified for body mass index (BMI), taking a wide range of possible confounders into account.
  
  
  METHODS
  Prospective, population based study.
  
  
  METHODS
  Male population of Malmö, Sweden.
  
  
  METHODS
  In all 5722 men were screened twice with a mean time interval of 6 years in Malmö, southern Sweden. They were classified according to BMI category at baseline (<21, 22-25, overweight: 26-30, and obesity: 30+ kg m(-2)) and weight change category until second screening (weight stable men defined as having a baseline BMI +/- 0.1 kg m(-2) year-1 at follow-up re-screening).
  
  
  METHODS
  Non-cancer mortality calculated from national registers during 16 years of follow-up after the second screening. Data from the first year of follow-up were excluded to avoid bias by mortality caused by subclinical disease at re-screening.
  
  
  RESULTS
  The relative risk (RR; 95% CI) for non-cancer mortality during follow-up was higher in men with decreasing BMI in all subgroups: RR 2.64 (1.46-4.71, baseline BMI <21 kg m(-2)), 1.39 (0.98-1.95, baseline BMI 22-25 kg m(-2)), and 1.71 (1.18-2.47, baseline BMI 26+ kg m(-2)), using BMI-stable men as reference group. Correspondingly, the non-cancer mortality was also higher in men with increasing BMI, but only in the obese group (baseline BMI 26+ kg m(-2)) with RR 1.86 (1.31-2.65). In a subanalysis, nonsmoking obese (30+ kg m(-2)) men with decreased BMI had an increased non-cancer mortality compared with BMI-stable obese men (Fischer's test: P=0.001). The mortality risk for nonsmoking overweight men who increased their BMI compared with BMI-stable men was also significant (P=0.006), but not in corresponding obese men (P=0.094). CONCLUSIONS. Weight loss in self-reported healthy but overweight middle-aged men, without serious disease, is associated with an increased non-cancer mortality, which seems even more pronounced in obese, nonsmoking men, as compared with corresponding but weight-stable men. The explanation for these observational findings is still enigmatic but could hypothetically be because of premature ageing effects causing so-called weight loss of involution.
authors.affiliation: Department of Internal Medicine, University Hospital, Malmö, Sweden. peter.nilsson@medforsk.mass.lu.se
authors.forename: P M
authors.initials: PM
authors.lastname: Nilsson
authors.forename: J-A
authors.initials: JA
authors.lastname: Nilsson
authors.forename: B
authors.initials: B
authors.lastname: Hedblad
authors.forename: G
authors.initials: G
authors.lastname: Berglund
authors.forename: F
authors.initials: F
authors.lastname: Lindgärde
mesh_terms: D015992:Body Mass Index; D002423:Cause of Death; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009765:Obesity; D011159:Population Surveillance; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D011795:Surveys and Questionnaires; D013548:Sweden; D015431:Weight Loss