In a recent article published in BMC Public Health, researchers analyzed China Health and Nutrition Survey (CHNS) data collected between 2004 and 2015.

The study aimed to evaluate long-term associations of dietary patterns with central obesity and general obesity.

They considered increased waist circumference (WC), central obesity and defined general obesity.

Study: Association of dietary patterns with general and central obesity among Chinese adults: a longitudinal population-based study. Image Credit: Sorbis/Shutterstock.com

Background

In the past 20 years, general and central obesity has increased among Chinese adults of all age and gender groups in line with the global trend of rising obesity prevalence worldwide.

Per the Global Nutrition Report 2021 estimates, the number of obese adults worldwide is ~772 million, i.e., they have almost tripled in recent decades.

Given its multifactorial etiology, obesity is influenced by dietary habits. However, since the relationship of diet with the development of obesity is complex, it is not fully understood. Additionally, nutritional habits vary substantially among nations, societies, and ethnicities.

In China, more people are adopting Westernized dietary habits, bringing an enormous transformation in Chinese society, wherein people are shifting from a traditional Chinese diet rich in carbohydrates and cooked vegetables to a diet comprised of animal-based, nutrient-dense, and energy-rich foods.

Most previous studies used a cross-sectional design to examine dietary patterns and their associations with obesity in China.

Accordingly, these studies could not evaluate the long-term associations between dietary patterns and the two obesity phenotypes, central and general obesity, among Chinese adults.

Examining and characterizing dietary patterns and understanding their association with obesity in a large Chinese cohort of adults could help establish the influence of diet on the risk of obesity that would be specific to Chinese society undergoing rapid social and economic development.

About the study

The CHNS is a household-based longitudinal survey initiated in 1989 to gather nutritional and health, demographic, socio-economic, and lifestyle data from two cities and four counties of each of the 15 Chinese provinces surveyed. All participating Chinese provinces varied in demography, geography, economic development status, and public resources. 

The CHNS is ongoing and uses a multistage random-cluster process to randomly draw the study samples from the population of these Chinese provinces regularly.

In this study, CHNS data collected during the 2004 wave served as the baseline data, which provided dietary assessment information for 8,377 Chinese adults aged 18–65.

However, after excluding participants with missing anthropometric data, the final longitudinal dataset of the current study comprised 4,207 participants.

The team assessed the dietary pattern of all 4,207 study participants through three consecutive 24-hour dietary recalls. They also used a household food inventory that consolidated food into 21 categories based on culinary use and nutrient profiles.

Next, the researchers performed an exploratory factor analysis to identify the dietary patterns of 4,207 participants at baseline, wherein input was the estimated intake of 21 food groups in grams/day.

In addition, they examined the obesity statuses of all participants in 2015. Then, they divided factor scores into quartiles (Q1-Q4) for further analysis.

Furthermore, the researchers used logistic regression models to determine the association between dietary patterns and obesity risk. The study outcomes were anthropometric measures, such as height, WC, weight, and BMI. 

Results

The current multicenter, longitudinal study remarkably captured three distinct dietary patterns, traditional southern, modern, and traditional northern, from 21 predefined food groups at baseline, explaining 23.25% of the variance in dietary intake of the 4,207 study participants.

The traditional southern pattern represented higher consumption of rice, fresh legumes, vegetables, pork, seafood, fish and a lower intake of corn, wheat, and coarse grains. 

Rice is considered a low-energy-density food because it absorbs more water while cooking than wheat. Thus, it had a protective role in developing general and central obesity.

This finding, however, is controversial because some studies conducted in South Korea and Japan have associated high rice consumption with an increased risk of obesity. One explanation for this discrepancy is that rice comes in many varieties and is cooked differently in different regions worldwide.

The protective role of the traditional southern diet on obesity might be attributable to fresh vegetables, which are rich sources of dietary fiber, whose higher intake is associated with a reduced risk of obesity.

In addition, the traditional southern diet included fish, a rich source of omega-3 polyunsaturated fatty acids (n-3 PUFAs), which controls weight gain by regulating lipid metabolism.

The modern dietary pattern represented higher consumption of fruits, poultry, eggs, and animal-based products, including dairy.

The third dietary pattern, traditional northern, was rich in wheat bread & buns, starchy roots, and tubers, fresh legumes but included lesser quantities of pork, poultry, fish, and seafood.

The authors noted that general and central obesity was more prevalent in Chinese adults following this dietary pattern. Accordingly, adults in the highest quartile (Q4) of the 'traditional northern' dietary pattern had higher odds ratios (ORs) of general obesity (OR = 1.61).

Conclusions

Overall, the northern dietary pattern represented a low-nutrient-density diet, as it had fewer food types and provided fewer micronutrients than the traditional southern nutritional pattern, which had an inverse association with the risk of developing general and central obesity in later life.

Furthermore, the study demonstrated the crucial roles of certain food groups in obesity. Thus, increasing the frequency and intake of those healthy food groups and adopting a varied eating pattern could help maintain appropriate energy intake, which, in turn, might reduce the risk of obesity. 

In the larger context, the study data might inform the development of nutritional interventions backed by robust scientific evidence to control the ongoing obesity epidemic.

Written by

Neha Mathur

Neha is a digital marketing professional based in Gurugram, India. She has a Master’s degree from the University of Rajasthan with a specialization in Biotechnology in 2008. She has experience in pre-clinical research as part of her research project in The Department of Toxicology at the prestigious Central Drug Research Institute (CDRI), Lucknow, India. She also holds a certification in C++ programming.