Better Dietary Knowledge and Socioeconomic Status (SES), Better Body Mass Index? Evidence from China—An Unconditional Quantile Regression Approach

Abstract

Obesity is a rapidly growing public health threat in China. Improvement of dietary knowledge may potentially reduce the risk of obesity and being overweight. However, existing studies focus on measuring the mean effects of nutrition knowledge on body mass index (BMI). There is a lack of literature on the effect of dietary knowledge on BMI, and the potential heterogeneity of the effect across the whole BMI distribution and across socioeconomic status (SES) groups. This study aims to investigate the heterogeneous nature of the relationship between dietary knowledge, SES, and BMI, using data from the China Health and Nutrition Survey (CHNS) in 2015. We employed unconditional quantile regression (UQR) to assess how the relationship between dietary knowledge, SES, and BMI varies across the whole BMI distribution, and conducted subgroup analyses using different socio-economic subsamples. Results indicate that dietary knowledge had no statistically significant impact on BMI across the BMI distribution. There was a large degree of heterogeneity in the SES effect across the BMI distribution as well as a major gender difference in the SES effect on BMI. Education had a significant and inverse association with BMI across the BMI distribution, greater at higher BMI quantiles. Income growth had a larger effect on the 50th quantile of BMI for males in the middle-income group, but was not significant for females. As income increased, males without college educations had higher BMI while females with college or higher education generally had lower BMI. The findings of this study reveal the heterogeneous nature of the relationship between SES, gender, and obesity across the entire BMI distribution, suggesting that quantile regressions might offer a valuable framework for exploring the complex relationship of dietary knowledge, demographic, and socio-economic factors on obesity.

Trends and Associated Factors of Dietary Knowledge among Chinese Older Residents: Results from the China Health and Nutrition Survey 2004–2015

“…Some controversial results were also reported regarding the associated factors of the dietary knowledge level. For example, Zhou et al [24] and Yu et al [25] found that the dietary knowledge of adults had no significant influence on overweight and obesity, possibly due to a lack of systematic dietary knowledge and inadequate guidance on overweight and obesity. While Laz et al [26] suggested that an increase in nutrition knowledge may promote healthy weight control behaviors among low-income reproductive-age women.…”

The Impact of Dietary Knowledge on Health: Evidence from the China Health and Nutrition Survey

“…Findings on the impact of dietary knowledge on health differ among different studies, which may be due to ignoring the heterogeneity of the samples [ 23 , 28 , 29 ]. Our heterogeneity analyses suggest that the impacts of dietary knowledge on health are stronger for individuals with a lower level of education and for rural residents.…”

“…Some scholars argue that more knowledge of diet usually leads to better health [ 11 , 26 ]. However, there are also studies suggesting that dietary knowledge is not translated into healthier food choices [ 27 ], and so has no positive impacts on health [ 28 , 29 ].…”

The Relation Between Prenatal Stress, Overweight and Obesity in Children Diagnosed According to BMI and Percentage Fat Tissue.

“…It is known that factors like too high energy supply, too little physical activity, a diet rich in simple sugars and saturated fatty acids increase the risk of overweight and obesity in children [13]. The results of some studies indicate that nutritional awareness is not signi cantly related to BMI, which means that the knowledge of the principles of proper nutrition is not su cient in the effective prevention of overweight and obesity [14,15]. The very knowledge of nutrition does not limit the scale of the phenomenon.…”