Influences of diet and physical activity on the change in body mass index and waist circumference in urban middle‐aged Chinese adults

Abstract

We measured diet and physical activity at baseline and to investigate their relationship to changes in body mass index (BMI) and waist circumference (WC) from 1998–2000 to 2002–2003 in 105 adults (51 men and 54 women) aged 35–49y at baseline and living in urban Beijing. Food intake was assessed with a 3‐day weighed food record, and physical activity was assessed by combining data from two activity monitors with a physical activity record. Both methods were validated in this population against the doubly labeled water method in our laboratory. Gender‐specific models were used because of clear overall interactions between gender and all predictors of BMI change (p=0.043) and WC change (p=0.053). For men, a higher physical activity level at baseline was associated with a decrease in WC (p=0.024) and a decrease in BMI (p=0.056). For women, physical activity was not a significant predictor of change in BMI or WC, but an increase in caloric beverage consumption was associated with gains in both BMI (p=0.042) and WC (p=0.022), and increased dietary protein was associated with a decrease in BMI (p=0.044). These findings suggested a gender effect on the relationship between diet, physical activity and weight change over time. Whereas physical activity was a significant predictor of 3‐year weight change in men, only dietary variables were significant in women in this population.Research support: Nestle Foundation.