BACKGROUND: The mechanisms distinguishing metabolically healthy from unhealthy phenotypes within the same BMI categories remain unclear. This study aimed to investigate the associations between regional fat distribution and metabolically unhealthy phenotypes in Chinese adults across different BMI categories. METHODS: This cross-sectional study involving 11833 Chinese adults aged 20 years and older. Covariance analysis, adjusted for age, compared the percentage of regional fat (trunk, leg, or arm fat divided by whole-body fat) between metabolically healthy and unhealthy participants. Trends in regional fat percentage with the number of metabolic abnormalities were assessed by the Jonckheere-Terpstra test. Odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated by logistic regression models. All analyses were performed separately by sex. RESULTS: In non-obese individuals, metabolically unhealthy participants exhibited higher percent trunk fat and lower percent leg fat compared to healthy participants. Additionally, percent trunk fat increased and percent leg fat decreased with the number of metabolic abnormalities. After adjustment for demographic and lifestyle factors, as well as BMI, higher percent trunk fat was associated with increased odds of being metabolically unhealthy [highest vs. lowest quartile: ORs (95%CI) of 1.64 (1.35, 2.00) for men and 2.00 (1.63, 2.46) for women]. Conversely, compared with the lowest quartile, the ORs (95%CI) of metabolically unhealthy phenotype in the highest quartile for percent arm and leg fat were 0.64 (0.53, 0.78) and 0.60 (0.49, 0.74) for men, and 0.72 (0.56, 0.93) and 0.46 (0.36, 0.59) for women, respectively. Significant interactions between BMI and percentage of trunk and leg fat were observed in both sexes, with stronger associations found in individuals with normal weight and overweight. CONCLUSIONS Trunk fat is associated with a higher risk of metabolically unhealthy phenotype, while leg and arm fat are protective factors. Regional fat distribution assessments are crucial for identifying metabolically unhealthy phenotypes, particularly in non-obese individuals.
Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Young Adult ; Adipose Tissue ; Body Fat Distribution ; Body Mass Index ; China/epidemiology* ; Cross-Sectional Studies ; Health Surveys ; Phenotype

Objective: To investigate cardiovascular disease (CVD) prevention status among residents with intra-urban migration in Central China, so as to provide insights into targeted prevention and control of CVD. Methods: Basic data of residents aged 35 to 75 years who participated in Early Screening and Comprehensive Intervention Project for CVD high-risk populations in Central China from September 2015 to August 2020 were collected. According to birth place, type of registered residence and current residence, residents were divided into four groups: local residents in old urban area, local residents in new urban area, other urban migrants and other rural migrants. The status of CVD primary and secondary prevention, were analysed by using a robust Poisson regression model. Results: A total of 76 513 residents were recruited, including 29 420 males (38.45%) and 47 093 females (61.55%), and had a mean age of (56.36±9.84) years. There were 45 087 (58.93%) local residents in old urban area, 23 868 (31.19%) local residents in new urban area, 5 668 (7.41%) other urban migrants and 1 890 (2.47%) other rural migrants. After adjusting for variables such as age, gender and educational level, the results of robust Poisson regression analysis showed that compared with local residents in old urban area, local residents in new urban area had lower compliance rates of non- or moderate-drinking (RR=0.987, 95%CI: 0.975-1.000) and healthy diet (RR=0.535, 95%CI: 0.365-0.782), lower proportion of using aspirin as primary prevention in CVD high-risk population (RR=0.616, 95%CI: 0.511-0.741), lower awareness (RR=0.873, 95%CI: 0.782-0.974) and control rates (RR=0.730, 95%CI: 0.627-0.849) of hypertension; other urban migrants had higher compliance rate of non-smoking (RR=1.045, 95%CI: 1.017-1.075); other rural migrants had lower proportion of using aspirin as primary prevention in CVD high-risk population (RR=0.826, 95%CI: 0.707-0.966). Conclusion The CVD primaryprevention among local residents in new urban area is relatively poor among four groups of residents in Central China, and key interventions are needed.