[Relationship between the percentage of energy intake from macronutrients and obesity among adult residents in 15 provinces of China in 1991-2018].

OBJECTIVE: To explore the relationship between the percentage of energy intake from macronutrients and obesity in Chinese adult residents, and analyze the cut-off values of macronutrients for predicting obesity. METHODS: Data was collected in China Health and Nutrition Survey(CHNS)in 1991-2018. Adults who participated in at least two waves of the surveys and were not obese at baseline were selected as the study subjects. Obesity was defined as body mass index(BMI)≥28.0 kg/m~2. Generalized estimating equation was used to analyze the relationship between the percentage of energy intake from macronutrients and BMI and obesity, and receiver operating characteristic curve(ROC) was used to analyze the cut-off values of percentage of energy intake from macronutrients to predict obesity. RESULTS: The percentage of energy intake from protein and fat of adult residents in 15 provinces(autonomous regions and municipalities) in China showed an increasing trend(P<0.01), and the percentage of energy intake from carbohydrate showed a decreasing trend(P<0.01) between 1991 and 2018. After adjusting for covariates, the group of percentage of energy intake from fat in 20%～30%(ß=0.05, 95%CI 0.01-0.08)and ≥30%(ß=0.15, 95%CI 0.11-0.18)were positively correlated with BMI compared with the group of percentage of energy intake from fat <20%, and the risk of obesity in 20%-30% and ≥ 30% was increased by 17%(OR=1.17, 95%CI 1.04-1.31)and 6%(OR=1.06, 95%CI 1.24-1.56), respectively. Compared with the group of the percentage of energy intake from carbohydrate < 50%, the group of 50% to 65%(ß=-0.08, 95% CI-0.11--0.05) and ≥ 65%(ß=-0.17, 95%CI-0.20--0.13) was negatively correlated with BMI, and the percentage of energy intake from carbohydrate ≥ 65% reduced the risk of obesity(OR=0.71, 95%CI 0.63-0.80). CONCLUSION: Carbohydrate intake was inversely correlated with the risk of obesity, and fat intake was positively correlated with the risk of obesity. Moderate intake of carbohydrates and reduced fat intake can prevent obesity.

[Relationship between physical activity and muscle mass loss among people aged 60 and above in 15 provinces of China in 2015].

OBJECTIVE: To analyze the relationship between physical activity and muscle mass loss among Chinese elderly aged 60 years and above in 15 provinces. METHODS: Data was collected from 2015 China Nutritional Transition Cohort Study. Information on demographic characteristics and physical activity was investigated by questionnaire. Dietary intake was estimated from three consecutive 24-h recalls for each individual. Appendicular skeletal muscle mass(ASM) was assessed using the bioelectrical impedance analysis(BIA). Skeletal muscle mass(SMI) loss was diagnosed according Asian working group of sarcopenia(AWGS) 2019 recommendation(male: SMI <7.0 kg/m~2, female: <5.7 kg/m~2). A total of 4565 participants aged 60 years and above from 15 provinces in China with complete information were included in the final analysis. Different domains(occupational, domestic, travel and leisure), light physical activity(<3.0 METs), moderate physical activity(3.0-5.9 METs) and vigorous physical activity(≥6.0 METs) of physical activity among elderly adults were evaluated. Logistic multilevel model was used to analyze the relationship between low muscle mass and different intensity of physical activity duration. RESULTS: Among all participants aged 60 years and above in 15 provinces of China in 2015, women's participation rate in domestic physical activity was 91.7%, which was higher than men's rate of 62.3%. However, men's participation rate in occupational, travel and leisure physical activity were higher than those of women. The participation rate, duration of light physical activity and moderate physical activity were higher in women than in men(light physical activity: female duration 11.0 h/week vs. male duration 3.5 h/week; female participation rate 89.9% vs. male participation rate 62.8%; moderate physical activity: female duration 7.0 h/week vs. male duration 4.7 h/week; female participation rate 90.6% vs. male participation rate 75.2%). The median vigorous physical activity was 0 h/week in both male and female group. The prevalence of muscle mass loss was 13.9% among subjects. The median weekly light physical activity and moderate physical activity in muscle mass loss group were 5.8 h and 4.7 h, which were lower than in non-muscle mass loss group(9.3 h and 6.0 h). The OR of muscle mass lass was 0.71(95%CI 0.42-0.98, P<0.05) for the male with 3.5-6.9 hours of moderate physical activity per week, compared to moderate physical activity less than 3.5 h/week. And OR of the female was 0.67(95%CI 0.47-0.95, P<0.05). CONCLUSION: The vast majority of physical activity in China among the elderly is domestic and light physical activity. Light physical activity and moderate physical activity duration increments in female and moderate physical activity duration increments in male were associated with decreased risk of muscle mass loss.

[Designing effective front-of-package warning labels for prepackaged food in China:based on Delphi method].

OBJECTIVE: To design front-of-package warning labels for prepackaged food adapted to the Chinese context. METHODS: Delphi method was used to evaluate the first graft of indicatorsof the front-of-package warning labels. The front-of-package warning labels suitable for China's national conditions was selected according to the direct scoring method. RESULTS: 4 sets of front-of-package warning labels for prepackaged food were selected after two rounds of Delphi expert method. CONCLUSION: The final draft of the front-of-package warning labels for prepackaged food is in line with expectations.

[Evaluation of the front-of-package warning labels of prepackaged food in China based on focus group discussion].

OBJECTIVE: To understand the public's perceptions and preferences on the designed front-of-package warning labels of prepackaged food, and to evaluate and identify the effective warning label. METHODS: A total of 116 participants were recruited from six provinces(autonomous regions/municipalities) in China. Focus group discussions were conducted with four types of warning labels on prepackaged food. And the score of attitude on different warning labels were compared. RESULTS: There was no difference in the total score of the four warning labels. Total score of black shield label was higher in citizen participants and college education level participants than in their respective counterparts(P<0.05). Parents or primary caregiver of children under 16 years old gave higher scores to each labels than their respective counterparts(P<0.05). The black shield label was most likely to attract the attention of the respondents, most likely to influence the decision on eating and drinking, and most likely to have an unhealthy warning effect. The yellow hexagonal label was least likely to attract the attention of the respondents, least likely to affect the decision to eat and drink food, and least likely to have an unhealthy warning effect. CONCLUSION: Black shield warning label is the most effective.

[Development and validation of the nutrient-rich food index for China].

OBJECTIVE: To select the nutrient-rich food(NRF) index applicable to the food characteristics of Chinese residents through population-based dietary quality validation. METHODS: Sixteen NRF indices were constructed based on the Chinese Food Composition Table and the Chinese Food Labelling Nutrient Reference Values, using 100 g as the base amount of food for calculation. The NRF indices were validated by the China Prime Diet Quality Score(CPDQS), a dietary quality assessment index, using food intake data collected from 14 068 adult residents in 15 provinces in 2018 under the China Health and Nutrition Survey. The CPDQS was used as the dependent variable and the dietary NRF index score was used as the independent variable. The multiple linear regression models were performed after adjusting the covariates and the NRF index with the largest coefficient of determination R~2 was used as the most appropriate index. RESULTS: Regression analysis showed that the R~2 of NRF8.2 index was the largest, which was 0.16. Dried legumes, fungi and algae, nuts, vegetables, eggs and aquatic products scored higher on the NRF8.2 index. The high scoring subgroups had higher average daily intakes of cereals and potatoes, vegetables, fruits, soybeans and nuts, dairy, eggs and aquatic products, as well as lower consumption of livestock and poultry meat, beverages, salt and cooking oil, compared to the low scoring subgroup on the Dietary NRF8.2 Index. In terms of nutrient intake, the medium and high NRF8.2 subgroups had relatively high intakes of energy, protein, vitamins and minerals and relatively low intakes of fat and sodium. CONCLUSION: The NRF8.2 index explains the maximum variation in CPDQS and is a relatively suitable NRF index for the Chinese population.

Association of gut microbiota with glycaemic traits and incident type 2 diabetes, and modulation by habitual diet: a population-based longitudinal cohort study in Chinese adults.

AIMS/HYPOTHESIS: The gut microbiome is mainly shaped by diet, and varies across geographical regions. Little is known about the longitudinal association of gut microbiota with glycaemic control. We aimed to identify gut microbiota prospectively associated with glycaemic traits and type 2 diabetes in a geographically diverse population, and examined the cross-sectional association of dietary or lifestyle factors with the identified gut microbiota. METHODS: The China Health and Nutrition Survey is a population-based longitudinal cohort covering 15 provinces/megacities across China. Of the participants in that study, 2772 diabetes-free participants with a gut microbiota profile based on 16S rRNA analysis were included in the present study (age 50.8 ± 12.7 years, mean ± SD). Using a multivariable-adjusted linear mixed-effects model, we examined the prospective association of gut microbiota with glycaemic traits (fasting glucose, fasting insulin, HbA1c and HOMA-IR). We constructed a healthy microbiome index (HMI), and used Poisson regression to examine the relationship between the HMI and incident type 2 diabetes. We evaluated the association of dietary or lifestyle factors with the glycaemic trait-related gut microbiota using a multivariable-adjusted linear regression model. RESULTS: After follow-up for 3 years, 123 incident type 2 diabetes cases were identified. We identified 25 gut microbial genera positively or inversely associated with glycaemic traits. The newly created HMI (per SD unit) was inversely associated with incident type 2 diabetes (risk ratio 0.69, 95% CI 0.58, 0.84). Furthermore, we found that several microbial genera that were favourable for the glycaemic trait were consistently associated with healthy dietary habits (higher consumption of vegetable, fruit, fish and nuts). CONCLUSIONS/INTERPRETATION: Our results revealed multiple gut microbiota prospectively associated with glycaemic traits and type 2 diabetes in a geographically diverse population, and highlighted the potential of gut microbiota-based diagnosis or therapy for type 2 diabetes. DATA AVAILABILITY: The code for data analysis associated with the current study is available at https://github.com/wenutrition/Microbiota-T2D-CHNS.

Modifiable factors of 20-year blood pressure trajectories among normotensives and their associations with hypertension : a prospective study.

Little is known about the impact of modifiable risk factors on blood pressure (BP) trajectories and their associations with hypertension (HTN). We aimed to identify BP trajectories in normotensive Chinese adults and explore their influencing factors and associations with HTN. We used data from 3436 adults with at least four BP measurements between 1989 and 2018 in the China Health and Nutrition Survey, an ongoing cohort study. We measured BP using mercury sphygmomanometers with appropriate cuff sizes in all surveys. We used group-based trajectory modelling to identify BP trajectories between 1989 and 2009 and multiple logistic and Cox regression models to analyse their influencing factors and associations with HTN in 2011-2018. We identified five systolic blood pressure (SBP) trajectories, 'Low-increasing (LI)', 'Low-stable (LS)', 'Moderate-increasing (MI)', 'High-stable (HS)' and 'Moderate-decreasing (MD)', and four diastolic blood pressure (DBP) trajectories classified as 'Low-increasing (LI)', 'Moderate-stable (MS)', 'Low-stable (LS)' and 'High-increasing (HI)'. People with higher physical activity (PA) levels and lower waist circumferences (WC) were less likely to be in the SBP LI, MI, HS and MD groups (P < 0·05). People with higher fruit and vegetable intakes, lower WCs and salt intakes and higher PA levels were less likely to be in the DBP LI, MS and HI groups (P < 0·05). Participants in the SBP HS group (hazard ratio (HR) 2·01) or the DBP LI, MS and HI groups (HR 1·38, 1·40, 1·71, respectively) had higher risks of HTN (P < 0·05). This study suggests that BP monitoring is necessary to prevent HTN in the Chinese population.

Trajectories of energy intake distribution and subsequent risk of hyperglycemia among Chinese adults: findings from the China Health and Nutrition Survey (1997-2018).

AIMS: Few studies have examined the secular trend of the energy intake distribution, and its effect on future risk of hyperglycemia. This study aims to describe trajectories of energy intake distribution over 12 years and relate them to subsequent risk of hyperglycemia over 9 years of follow-up. METHODS: Our study used ten waves of data from the CHNS survey, a population-based longitudinal survey in China, ongoing since 1989. We examined a cohort of adult participants who were free from diabetes but had at least three waves of dietary data from 1997 to 2009. We assessed energy intake using three consecutive 24 h recalls. We used these data to identify trajectory groups of energy intake distribution by multi-trajectory model based on energy intake proportions of breakfast, lunch, and dinner. We followed up participants for hyperglycemia, diabetes, and impaired fasting glucose for 9 years from 2009 to 2018. Outcomes were ascertained with fasting glucose, serum HbA1c, and self-report of diabetes and/or glucose-lowering medication. We estimated relative risk (RR) for hyperglycemia, diabetes, and impaired fasting glucose by identified trajectory groups using multilevel mixed-effects modified Poisson regression with robust (sandwich) estimation of variance. Gender difference was additionally examined. RESULTS: A total of 4417 participants were included. Four trajectory groups were identified, characterized and labeled by "Energy evenly distributed with steady trend group" (Group 1), "Dinner and lunch energy dominant with relatively steady trend group" (Group 2), "Dinner energy dominant with increasing trend and breakfast energy with declining trend group" (Group 3), and "breakfast and dinner energy dominant with increasing trend group" (Group 4). During 48,091 person-years, 1053 cases of incident hyperglycemia occurred, 537 cases of incident diabetes occurred, and 516 cases of impaired fasting glucose occurred. Compared with Group 1, Group 3 was associated with higher subsequent risk of incident hyperglycemia in 9 years of follow-up (RR = 1.28, 95% CI = 1.02, 1.61). No association was found for incident diabetes and impaired fasting glucose. Among males, Group 3 was associated with higher risk of incident hyperglycemia in 9 years of follow-up (RR = 1.44, 95% CI = 1.07, 1.94). No relationship was found in females. CONCLUSIONS: Energy intake distribution characterized by over 40% of energy intake from dinner with a rising trend over years was associated with higher long-term risk of hyperglycemia in Chinese adults.

Disparities in fresh fruit and vegetable intake by sociodemographic and behavioural factors among adults in China.

OBJECTIVE: To measure the associations of sociodemographic and behavioural factors with fruit and vegetable consumption among adults in China. DESIGN: A cross-sectional study. SETTING: A 2015 wave of the China Health and Nutrition Survey. PARTICIPANTS: Totally, 11 910 adults aged 18 to 64 years. RESULTS: Adjusted log binomial regression analyses showed that adults with higher income levels had higher fruit intake than those with low income levels (medium income group, risk ratio (RR): 1·28; 95 % CI: 1·16, 1·41; high income group, RR: 1·58; 95 % CI: 1·43, 1·74). Current smokers had lower fruit intake than non-smokers (RR: 0·86; 95 % CI: 0·77, 0·96). Adults living in southern China had higher vegetable intake (RR: 1·88; 95 % CI: 1·76, 2·01) but lower fruit intake (RR: 0·85; 95 % CI: 0·79, 0·91) than adults in northern China. With increasing age, adults had higher fruit intake (50-64 years, RR: 1·20; 95 % CI: 1·09, 1·33; reference category 18-34 years) and higher vegetable intake (35-49 years, RR: 1·13; 95 % CI: 1·05, 1·22; 50-64 years, RR: 1·22; 95 % CI: 1·13, 1·31). CONCLUSIONS: Our findings identify a range of sociodemographic and behavioural factors associated with fruit and vegetable consumption among Chinese adults. They also point to the need for public health nutrition interventions for socially disadvantaged populations in China.

[Snacking behaviors of Chinese female adults aged 18 to 49 years old in 2004-2015].

OBJECTIVE: To describe shift in snacking behavior among Chinese female adults aged 18 to 49 years old in 2004-2015, and to analyze the contribution of snacks to energy and nutrients among them. METHODS: The present study used data from "China Health and Nutrition Health" where a multistage stratified cluster design was employed to select a stratified probability sample. A total of 12 523 female participants aged 18-49 years old who participated in surveys conducted in 2004-2015 with completed data of demographic characteristics and dietary measurementswere selectedas subjects. There were 2376, 2149, 2142, 2844 and 3012 subjects in waves of 2004, 2006, 2009, 2011, and 2015, respectively. Multivariate Logistic regression model was used to analyze the relationship between socioeconomic factors and snack consumption. Generalized linear model was used to analyze the energy and nutrient intake of snack consumers and non-snack consumers, as well as the contribution of snacks to energy and nutrients. RESULTS: The consumption rate of snacking for women aged 18 to 49 years old had an increasing trend over time(P<0.05), and the rate was 14.24% in 2015, 3.5 times as high as that in 2004. Participants aged 18 to 29 years old whose snake consumption rates were relatively higher compared to those of other aged groups in general waves; also, female adults from the higher education group, the higher yearly income group, and the higher urbanicity index group, and those with the history of smoking or the alcohol use tended to consumed snacks. The change of the influential factors in relation to the consumption of the participant's snack was observed, and age, income level, education level, living area, and the behavior of smoking and drinking were all important factors of snacking. The daily energy and nutrient intake of female snack consumers aged 18 to 49 years old was higher than that of non-snack consumers. The contribution rate of snacks to energy and nutrients varies significantly between survey years; and the contribution of snacks to energy and main nutrients was more than 20% in 2011. CONCLUSION: Snacks have become an important part of the diet of Chinese women aged 18 to 49 years old. Future health promotion programs should be targeted on nutrition education and intervention to guide a reasonable diet structure.

[Secular trends in food intakes among the elderly aged 60 and older in nine provinces in China from 1991 to 2015].

OBJECTIVE: To analysis the status and trend of food intake of elderly aged 60 and older years old in nine provinces of China. METHODS: The data of China Health and Nutrition Survey from 1991 to 2015 were used, which elderly ≥60 years old were selected as the subjects. The dietary survey used compared. The 3-consecutive day-24-hour dietary recall was used to collect information on food intake, the condiment intake was collected by weighting and bookkeeping method. RESULTS: The intakes of cereals and tubers and vegetables among the elderly were 363.3 g/d and 249.1 g/d, respectively in 2015, decreased by 65.4 g/d and 17.6 g/d as compared with those in 1991. The intakes of meat, egg, and edible oil were 56.7 g/d, 19.2 g/d and 27.5 g/d respectively and increased by 7.5 g/d, 19.2 g/d and 2.5 g/d as compared to those with 1991. The intakes of eggs, soybeans and nuts were higher among the elderly people having high income or living in urban areas. In 2015, the proportion of elderly in nine provinces of China whose intake of vegetables, fruits, soybeans, milk and dairy products was lower than the recommended amount was relatively high. The proportion of meat higher than the recommended value is higher than that of aquatic products and eggs. Oil, salt and other limited flavoring intake of less than and above the limit was nearly 50 percent of the population. CONCLUSION: There are three problems in the diet of the elderly in nine provinces in China: the structure of diet is not rational; low intake of the food rich in high quality protein and low fat such as aquatic products, eggs, dairy products and so on; the problem of excessive oil and salt in food.

[Multilevel study on the effects of dietary nutrients on body mass index of Chinese children and adolescents aged 7-17].

OBJECTIVE: Analyze the relationship between dietary nutrients and body mass index of children and adolescents aged 7-17 in China. METHODS: The data comes from the "China Health and Nutrition Survey", and 5562 children and adolescents aged 7-17 who participated in at least one round(2000, 2006, 2011 and 2015) of the survey and had complete dietary and physical measurement survey data were selected as the research objects. A three-level(community-individual-observation level) linear random intercept mixed effect model of body mass index was constructed to analyze the influence of dietary nutrient intake of children and adolescents of different genders in urban and rural areas on their body mass index(BMI).24 hours for 3 consecutive days and family weight accounting were used to evaluate the dietary nutrient intake. RESULTS: BMI of urban children and adolescents is higher than that of rural children and adolescents. The BMI of children and adolescents aged 12-17 is higher than that of children and adolescents aged 7-11. BMI of boys was higher than that of girls, but the difference was statistically significant only in 2011 and 2015. After controlling for confounding factors such as individual level(survey year, age, physical activity and family per capita income) and community level(community urbanization index), the three-level model showed that the BMI of rural boys increased with the increase of cholesterol intake(P<0.01). BMI of urban girls increased with the increase of vitamin B_1 intake(P<0.05) and iron intake(P<0.01). BMI of rural girls increased with the increase of vitamin E intake(P<0.001) and sodium intake(P<0.05). CONCLUSION: There are some differences in dietary nutrients that affect the BMI level of 7-17 years old children and adolescents between urban and rural areas.

[Trends of overweight and obesity among children and adolescents aged 7-17 in 16 provinces of China from 2000 to 2018].

OBJECTIVE: To analyze the distribution characteristics and trends of overweight and obesity in children and adolescents aged 7-17 years in 16 provinces of China. METHODS: Data were collected from China health and nutrition survey in 2000, 2006, 2011, 2015 and 2018, 8398 children and adolescents aged 7-17 with complete data were selected as the research objects. Overweight and obesity were classified by body mass index(BMI) reference norm for screening overweight and obesity in Chinese children and adolescents. The distribution and trend of overweight and obesity among children and adolescents aged 7-17 in 16 provinces of China were analyzed by using Cochran-Armitage trend test and two-level random intercept model. RESULTS: The prevalence of overweight and obesity in children and adolescents aged 7-17 in China showed an upward trend from 2000 to 2018(P<0.05). The prevalence of overweight increased from 5.42% in 2000 to 12.92% in 2018, and the prevalence of obesity increased from 2.45% in 2000 to 12.36% in 2018. The result of multilevel model analysis showed that gender and urban and rural areas had significant effects on centralized BMI(P<0.05), the BMI increase value of boys was greater than that of girls(ß=0.2824), the BMI increase value of children and adolescents in rural areas was greater than that in urban areas(ß=0.5902). CONCLUSION: The prevalence of overweight and obesity among children and adolescents aged 7-17 in 16 provinces of China are increasing.

[Fat intake from pre-packaged foods among Chinese residents of 16 provinces in 2018].

OBJECTIVE: To investigate the impact of prepackaged food consumption on fat intake in 16 provinces of China in 2018. METHODS: Data used in present study was derived from the eleventh round of China Health and Nutrition Survey(CHNS), 17312 residents aged 6 and over were selected and their consumed information of pre-packaged food was collected. The consumption of pre-packaged food and fat intake from pre-packaged food in urban and rural areas, different age groups, different regions and different genders were calculated and compared. RESULTS: The median intake of fat from pre-packaged food among subjects and consumers were 33.6 g/d and 34.7 g/d, respectively.73.5% of the intake of fat from pre-packaged food comes from vegetable oil. CONCLUSION: Vegetable oil was the main source of fat from pre-packaged food for Chinese residents.

[Relationship between physical activity and cognition function among people aged 55 and above in 4 provinces of China].

OBJECTIVE: To analyze the relationship between different intensity of physical activity(PA) duration and cognitive function. METHODS: The 2018 Community-based Cohort Study on Nervous System Diseases used multi-stage stratified cluster randomization sampling method to select study participants. A total of 5571 participants aged 55 years and above from four provinces in China with complete information on demographic characteristics and PA and cognitive function were included in the final analysis. Basic information and PA data were collected by questionnaire. The Montreal cognitive assessment(MoCA) score method was adopted to evaluate the cognitive function. Light physical activity(LPA) duration and moderate-to-vigorous physical activity(MVPA) duration were calculated. Multivariate Logistic regression and Multiple linear regressions were used to analyze the relationship between different intensity of PA duration and the risk of mild cognitive impairment(MCI) and MoCA total score. RESULTS: The median(P25, P75) of LPA and MVPA were 7. 0(0. 0, 16. 3) and 7. 3(0. 0, 14. 0) hours per week in the non-MCI group among 5571 participants aged 55 years and above in four provinces of China in 2018. In the MCI group, the median duration were 9. 3(0. 0, 17. 5) and 7. 0(0. 0, 11. 7) hours per week. The Logistic analysis showed that the OR of MCI was 0. 63(95%CI 0. 49-0. 82, P<0. 05) for the elderly with 3. 6-7. 0 hours of MVPA per week, compared to the elderly without MVPA. The OR of MCI was 1. 26(95%CI 0. 94-1. 67, P>0. 05) for the elderly with 3. 6-7. 0 hours of LPA per week compared to the elderly without LPA. Multiple linear regression analysis showed that compared to the elderly without MVPA, the total MoCA score increased with LPA duration increased as the duration was less than 10. 5 hours per week. The MoCA score decreased with LPA duration increased as duration was between 10. 5 and 21. 0 hours per week. CONCLUSION: MVPA duration increment was associated with decreased prevalence of MCI and increased cognitive function in the elderly in four provinces of China. LPA duration should be maintained at an appropriate level in order to reduce the incidence of MCI and increased cognitive function in the elderly.

[Agreement analysis and result calibration by ordinary least product regression between bioelectrical impedance analysis and dual energy X-ray absorptiometry].

OBJECTIVE: To analyze agreement of body fat percentage measured by bioelectrical impedance analysis(BIA) and dual energy X-ray absorptiometry(DXA) in Chinese adults, and to calibrate BIA measurement by ordinary least product regression(OLP). METHODS: Volunteers aged 18-65 were recruited to measure total body fat percentage and trunk fat percentage by BIA(Tanita BC-601 F) and DXA(Hologic Discovery QDR), respectively. Agreement between the two methods was compared by OLP. Bootstrap method was used to do the internal validation of the calibration equation. The calibration effect was verified by the agreement analysis of the calibrated BIA result and the DXA result. RESULTS: Before calibration, all 95%CIs of the intercepts of the OLP regression lines did not include 0, and all 95%CIs of the slopes of the OLP regression lines did not include 1. 00. After calibration, all 95% CIs of the intercepts of the OLP regression lines included 0, and all 95% CIs of the slopes included 1. 00. CONCLUSION: There are fixed bias and proportion bias between BIA and DXA in measuring total body fat percentage and trunk fat percentage in Chinese men and women. Calibration should be considered when body fat percentage is measured by BIA.

Secular trends in sedentary behaviors and associations with weight indicators among Chinese reproductive-age women from 2004 to 2015: findings from the China Health and Nutrition Survey.

BACKGROUND: Overweight and obesity are rising among Chinese reproductive-age women, while some studies have focused on the relationship between sedentary behavior and obesity in certain populations, none has focused on Chinese reproductive-age women specifically. This study examined secular trends in leisure time sedentary behaviors (watching television time, computer time and reading time, and the total sedentary time) among Chinese reproductive-age women and the association of those behaviors with five weight indicators-body mass index (BMI), waist circumference (WC) and overweight, obesity, and abdominal obesity status. METHODS: A prospective cohort study was conducted with Chinese reproductive-age women aged 15-49 who had participated in two or more rounds of the China Health and Nutrition Survey (CHNS), and completed the questionnaire and anthropometric measurements. The exposure variables were the average weekly time spent on three leisure time sedentary behaviors (watching television, using computer, and reading) and the total sedentary time (the sum of the above three sedentary time and video game time). Mixed-effect linear models were produced to explore the secular trends of the mean hours of these sedentary behaviors and the total sedentary time after adjusting covariates. Models were also produced to study the effects of these types of sedentary behavior levels on BMI and WC. Mixed-effect logistic regression models were produced to study the effects of the sedentary behavior levels on overweight, obesity, and abdominal obesity status. RESULTS: The total sedentary time among the reproductive-age women increased over time across most of age, region, educational levels, and income groups from 2004 to 2015. Television hours fluctuated, it increased and then declined over time across most of age, region, and income groups. Computer hours continually increased over time across all age, region, educational level, and income groups. Reading hours gradually decreased over time across most of age, region, educational level, and income groups. Those with a moderate level of television time (14 to <35 h/week) had 1.08 cm larger WCs and were 1.31 times more likely to have abdominal obesity than those with a low level of television time (<14 h/week). Those with a high level of television time (≥35 h/week) had 1.74 cm larger WCs, 0.66 kg/m2 larger BMIs, were 1.50 times more likely to be overweight and were 1.47 times more likely to have abdominal obesity than those with a low level of television time (<14 h/week). Greater computer, reading time, and total sedentary time were not associated with WC, BMI, overweight, obesity, or abdominal obesity. CONCLUSIONS: These findings showed that among Chinese reproductive-age women ages 15-49, secular trends of computer time increased rapidly, reading time decreased gradually and television time fluctuated but showed not much difference from 2004 to 2015. The sharp increase in computer time far outweighed the decline in reading time. As a result, the overall sedentary behavior time of Chinese reproductive-age women gradually increased. These findings provided strong evidence that greater television time was significantly associated with higher BMI, WC, and higher risks of overweight, abdominal obesity among Chinese reproductive-age women. Computer, reading, and the total sedentary time were not associated with those weight indicators.

Correction to: Psychometric properties of the perceived stress scale in a community sample of Chinese.

An amendment to this paper has been published and can be accessed via the original article.

Psychometric properties of the perceived stress scale in a community sample of Chinese.

BACKGROUND: The Perceived Stress Scale (PSS) is a globally used and self-report scale measuring perceived stress. Three versions of PSS (PSS-14, PSS-10 and PSS-4) are available which comprise 14, 10 and 4 items respectively. However, the Chinese version of the PSS has not yet been validated in a large community-based general population. The aims of this study were to evaluate the psychometric properties of the Chinese PSS in a large community-based general population and to compare the appropriateness of the three versions of PSS. METHODS: A total of 9507 adults with at least a junior high school education and completed PSS-14 from the China Health and Nutrition Survey were involved in this study. The internal consistency reliability of PSS was assessed using Cronbach's alpha coefficient and confirmatory factor analysis was employed to test the construct validity. Modification index was used for model extension and the critical ratio was used for model restriction. RESULTS: The internal consistency coefficients were satisfactory for PSS-14 and PSS-10, but not for PSS-4. The corresponding Cronbach's alpha were 0.830, 0.754 and 0.473 respectively. A 2-factor structure was confirmed for the PSS-14 and PSS-10, and all items' standardized factor loadings exceeded 0.4 for either negative or positive factors. Given that item 12 loaded on both negative and positive factors for PSS-14 and the goodness of fit for PSS-14 was not acceptable, PSS-13 (PSS-14 excluding item 12) was studied. The construct validities of PSS-13 and PSS-10 were satisfactory, but the goodness of fit for PSS-10 were better than that for PSS-13. CONCLUSIONS: PSS-13 (PSS-14 excluding item 12) and PSS-10 have satisfactory psychometric properties. PSS-10 are more applicable to measure the perceived stress than PSS-13 in a large community-based general population in China.

The association between physical activity and body fat percentage with adjustment for body mass index among middle-aged adults: China health and nutrition survey in 2015.

BACKGROUND: The inverse association between physical activity and body fat percentage (%) varies among different populations. We aim to examine whether the significant association between them was uniform across the subpopulations after taking into account body mass index (BMI). METHODS: Our study relied on data from China Health and Nutrition Surveys in 2015, including 5763 participants aged 40-64 years from 15 regions. Physical activity was calculated as metabolic equivalent task hours per day (MET·h/d). Body fat% was measured by bioelectrical impedance analysis. Body mass index < 24 kg/m2 was defined as normal weight and BMI ≥ 24 kg/m2 was overweight/obese. The effects of physical activity on body fat% were estimated using the Kruskal-Wallis test among sex, age, BMI groups, education, income, region and urbanization. Quantile regression analyses were utilized to describe the relationship between physical activity and body fat% distribution. RESULTS: Older adults, overweight/obese, higher education, higher income, residents of central China and those living in areas of higher urbanization had the lower physical activity. Participants who engaged in the highest level of physical activity had 2.0 and 1.5% lower body fat% than the lowest level of physical activity group (23.4, 34.8%) for men and women, respectively. There were 10.4 and 8.8% of normal weight males and females called normal weight obese. Overall, 1 h extra 4.5 MET•h/d was significantly associated with 0.079 and 0.110% less total body fat% at the 75th and 90th percentiles in normal weight males, with 0.071% less at the 25th percentiles in overweight/obese males, with 0.046-0.098% less at the 25th to 90th percentiles in normal weight females, and with 0.035-0.037% less from the 50th to 90th percentiles in overweight/obese females. The inverse association between physical activity and total body fat% was stronger in normal weight obese participants than other subgroups. CONCLUSIONS: In middle-aged Chinese adults, the inverse association between physical activity and body fat% was only in particular subpopulations rather than the entire population. We should pay much attention to normal weight obese and give a suitable physical activity guideline taking into account people with different body fat%.