title: Rate of weight gain predicts change in physical activity levels: a longitudinal analysis of the EPIC-Norfolk cohort.
abstract: OBJECTIVE
  To investigate the relationship of body weight and its changes over time with physical activity (PA).
  
  
  METHODS
  Population-based prospective cohort study (Norfolk cohort of the European Prospective Investigation into Cancer and Nutrition, EPIC-Norfolk, United Kingdom).
  
  
  METHODS
  A total of 25 639 men and women aged 39-79 years at baseline. PA was self-reported. Weight and height were measured by standard clinical procedures at baseline and self-reported at 18-month and 10-year follow-ups (calibrated against clinical measures). Main outcome measure was PA at the 10-year follow-up.
  
  
  RESULTS
  Body weight and PA were inversely associated in cross-sectional analyses. In longitudinal analyses, an increase in weight was associated with higher risk of being inactive 10 years later, after adjusting for baseline activity, 18-month activity, sex, baseline age, prevalent diseases, socioeconomic status, education, smoking, total daily energy intake and alcohol intake. Compared with stable weight, a gain in weight of >2 kg per year in the short-, medium- and long-term was consistently and significantly associated with greater likelihood of physical inactivity after 10 years, with the most pronounced effect for long-term weight gain, OR=1.89 (95% CI: 1.30-2.70) in fully adjusted analysis. Weight gain of 0.5-2 kg per year over long-term was substantially associated with physical inactivity after full adjustment, OR=1.26 (95% CI: 1.11-1.41).
  
  
  CONCLUSIONS
  Weight gain (during short-, medium- and long-term) is a significant determinant of future physical inactivity independent of baseline weight and activity. Compared with maintaining weight, moderate (0.5-2 kg per year) and large weight gain (>2 kg per year) significantly predict future inactivity; a potentially vicious cycle including further weight gain, obesity and complications associated with a sedentary lifestyle. On the basis of current predictions of obesity trends, we estimate that the prevalence of inactivity in England would exceed 60% in the year 2020.
authors.affiliation: Medical Research Council Epidemiology Unit, Institute of Metabolic Science, Cambridge, UK.
authors.forename: R
authors.initials: R
authors.lastname: Golubic
authors.forename: U
authors.initials: U
authors.lastname: Ekelund
authors.forename: K
authors.initials: K
authors.lastname: Wijndaele
authors.forename: R
authors.initials: R
authors.lastname: Luben
authors.forename: K-T
authors.initials: KT
authors.lastname: Khaw
authors.forename: N J
authors.initials: NJ
authors.lastname: Wareham
authors.forename: S
authors.initials: S
authors.lastname: Brage
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004522:Educational Status; D002149:Energy Intake; D004739:England / Q000453:epidemiology; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology; D005082:Physical Exertion; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D057185:Sedentary Behavior; D012907:Smoking / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013997:Time Factors; D015430:Weight Gain