Secular trends in dietary intake and its association with anthropometric data: a USA–China comparison

Abstract We aimed to compare secular trends in diet, BMI and waist circumference (WC) between Chinese and American adults aged 20–64 years. Data were from the China Health and Nutrition Survey (1993–2015) and the USA National Health and Nutrition Examination Survey (1997–2016), including 80 448 Chinese adults (50·0 % men) and 54 787 American adults (47·2 % men). Following age-standardisation, sex-stratified Joinpoint regression was used to estimate the annual percent change (APC) and average annual percent change (AAPC), and to identify potential turning points. Daily energy intake significantly decreased in Chinese adults (men: AAPC = −0·92 %, P < 0·001; women: AAPC = −1·08 %, P < 0·001) but remained stable for American adults. A significant shift from carbohydrate to fat occurred in both Chinese and American adults; however, only a significant increase in protein intake was observed in Chinese adults. Chinese adults showed sustained increases in BMI (men: AAPC = 0·46 %, P < 0·001; women: AAPC = 0·25 %, P < 0·001) and WC (men: AAPC = 0·45 %, P < 0·001; women: AAPC = 0·21 %, P < 0·001). American adults showed a significant increase in WC (men: AAPC = 0·31 %, P < 0·001; women: AAPC = 0·49 %, P < 0·001), but not for BMI. A significant association was confirmed between daily energy and macronutrient intake, and age-standardised BMI and WC in Chinese; however, no such association was observed in Americans. The results suggested that total energy intake alone could not explain the epidemic of obesity. Emphasising dietary quality and physical activity might be the next step to curb the prevalence of obesity.