Public Health Nutrition

Research Article

Physical activity, diet and gene–environment interactions in relation to body mass index and waist circumference: The Swedish Young Male Twins Study

Nina Karneheda1, Per Tyneliusa2, Berit L Heitmana3 and Finn Rasmussena1a2 c1

a1 Child and Adolescent Public Health Epidemiology Group, Department of Public Health Sciences, Karolinska Institute, Norrbacka, SE-171 76, Stockholm, Sweden

a2 Division of Epidemiology, Stockholm Centre of Public Health, Norrbacka, SE-171 76, Stockholm, Sweden

a3 Research Unit for Dietary Studies and Danish Epidemiology Science Centre at the Institute of Preventive Medicine, Copenhagen University Hospital, Øster Søgade 18, 1399, Copenhagen, Denmark


Objective The aim of the present study was to examine the relationships between genetic susceptibility to obesity, physical activity (PA), dietary fibre, sugar and fat intakes and 4-year changes in body mass index (BMI) and attained waist circumference (WC) in a cohort of 287 monozygotic and 189 dizygotic young adult male twin pairs. Increased knowledge about interactions between genes and environment may provide insight into why some individuals are more prone to obesity than others.

Design Information about PA, BMI, dietary habits, WC and potential confounders was collected by questionnaire in 1998 and 2002. The cohort data were analysed by mixed linear models.

Results Twins with low PA attained larger WC than twins with high PA (difference 2.5 cm; 95% confidence interval (CI) 1.3, 3.6). The twins with the lowest fibre intake were found to have attained the highest WC and to have increased most in BMI (difference between highest and lowest fibre intakes: 1.6 cm, 95% CI 0.4, 2.9 and 0.45 kg m−2, 95% CI 0.15, 0.76, respectively). Furthermore, our results suggested the presence of interactions so that twins with genetic susceptibility to obesity were more prone to have larger WC if sedentary than twins without genetic susceptibility.

Conclusion PA and a diet rich in fibre may be protective against weight gain among younger adult men. An interaction between PA, genes and attained WC is a novel finding which needs confirmation by other studies.

(Received July 11 2005)

(Accepted December 14 2005)


c1 *corresponding author: Email