A Comparative Study on Body Fat Mass and Age-Related Changes Among Middle-Aged and Elderly Males of Ethnic Minorities in Guangxi, China

Objective: This study aimed to investigate the ethnic differences in body fat mass, its distribution, and, most importantly, the ethnicity-specific patterns of age-related changes among middle-aged and elderly males of five ethnic minorities (Miao, Yao, Maonan, Jing, Mulao) in Guangxi, China. Methods: A cross-sectional study was conducted with 1009 randomly selected men aged ≥45 years. Body composition was assessed using bioelectrical impedance analysis, measuring key indicators including total fat mass (FM), visceral fat mass (VFM), and subcutaneous fat mass (SFM). Obesity was defined using body mass index (BMI), waist-to-hip ratio (WHR), and percentage body fat (PBF) criteria. Results: The analysis revealed three key findings: Significant ethnic disparities: Jing males exhibited consistently higher values across all fat mass indicators compared to the other four groups, while Yao and Mulao males generally had the lowest. High prevalence of undiagnosed abdominal obesity: The prevalence of abdominal obesity (WHR ≥0.9) exceeded 60% in four ethnic groups. Crucially, over 90% of these abdominally obese individuals were not classified as obese by BMI or PBF criteria, indicating a severe underdiagnosis of metabolic risk. Divergent age-related trajectories: A significant Ethnicity × Age Group interaction was found for FM and VFM. Distinct trends were identified: Jing and Mulao males showed a progressive increase in visceral fat with age; Yao males exhibited a continuous decline; Miao males demonstrated a U-shaped trend; and Maonan males peaked in the 55–64 year age group. Conclusion: There are profound ethnic-specific differences in both the amount and the temporal patterns of body fat accumulation among these populations. The high prevalence of abdominal obesity, which is largely missed by conventional BMI screening, coupled with the escalating risk of visceral adiposity in specific groups like the Jing, underscores an urgent need for targeted public health interventions that incorporate waist-to-hip ratio measurement and consider ethnic background for effective obesity prevention and control.