Longitudinal analysis of lifestyle habits in relation to body mass index, onset of overweight and obesity: Results from a large population-based cohort in Sweden

Aims: It is currently unknown whether the prevalence of obesity is increasing or has levelled off in Sweden and other Westernised countries. Given the major importance of lifestyle habits on weight status, we aimed to explore associations of longitudinal changes in lifestyle habits with changes in body mass index (BMI), and the onset of overweight and obesity. Methods: Participants (aged 18-84 years at baseline) were included from the Stockholm Public Health Cohort 2002-2010 (n=23,108). Weight status was from self-reported height and weight. Investigated lifestyle habits were leisure-time physical activity, and fruit, alcohol and smoking habits. We estimated associations of stable, improving or worsening lifestyle habits with longitudinal changes in BMI and onset of overweight or obesity between 2002 and 2010. Results: Both men and women increased in weight during the eight years of follow-up. Incidence of obesity was lower in men who increased their leisure-time physical activity (Relative Risk [RR]=0.58, 95% confidence interval 0.42-0.81) than in inactive individuals; the same applied to women (RR=0.37, 0.25-0.54), and similar patterns were identified for overweight and BMI in both genders. Smoking cessation was associated with onset of obesity for men (RR=1.69, 1.15-2.50) and women (RR=1.99, 1.39-2.85). Stable low alcohol intake or decreasing alcohol intake and daily fruit intake was associated with less weight gain, but only in men. Conclusions: Improving physical activity in both men and women, and alcohol habits and fruit intake in men, prevents excess weight gain among adult people in Sweden. Such an improvement might diminish weight gain after smoking cessation.