Changes in body mass index and the prevalence of XXXX during 1994-2008: repeated cross-sectional surveys and longitudinal analyses. The Troms   Study.

@entity1 @entity28
OBJECTIVES: To determine the mean body mass index (BMI, kg/m(2)) and prevalence of low weight (BMI<20) and @entity28 (BMI>= 30) in 3 population-based surveys, and to describe the longitudinal changes during 1994-2008 in mean BMI, and the prevalence of low weight and @entity28 . SETTING: A population study in Troms  , Norway. @entity1 : A total of 29   688 different @entity1 in 1 or more of 3 surveys (1994-1995, 2001-2002 and 2007-2008). Longitudinal analyses comprised 9845 @entity1 aged 25-69 in 1994 who participated in the 1994-1995 and 2007-2008 surveys and 4202 @entity1 and @entity1 who participated in all 3 surveys. OUTCOME MEASURES: Mean age-specific and sex-specific BMI, prevalence of low weight and @entity28 , and changes in BMI and prevalence of low weight and @entity28 during 1994-2008, according to sex and birth cohort. RESULTS: The age-adjusted (ages 30-84) prevalence of @entity28 increased from 9.8% and 11.8% in @entity1 and @entity1 , respectively, in 1994-1995 to 20.9% and 18.5%, respectively, in 2007-2008. The increase in mean age-adjusted BMI was stronger from 1994-1995 to 2001-2002 than from 2001-2002 to 2007-2008. Longitudinal results confirmed that the change in BMI from 1994-1995 to 2001-2002 was larger (0.9   kg/m(2) (95% CI 0.8 to 1.0) in @entity1 and 1.3   kg/m(2) (95% CI 1.2 to 1.4) in @entity1 ) than from 2001-2002 to 2007-2008 (0.2   kg/m(2) (95% CI 0.1 to 0.3) in @entity1 and @entity1 ). The most recently born had the largest increase (p<0.001). CONCLUSIONS: The mean BMI and the prevalence of @entity28 are still increasing in Troms  , and the increase is strongest in the youngest age groups. However, the increase in BMI was less marked in the last period (from 2001-2002 to 2007-2008) than in the first period (1994-1995 to 2001-2002).
