Body fat distribution and aging: Unveiling association and potential intervention strategies

BACKGROUND: Body mass index (BMI) has limitations in reflecting body fat distribution and its implications on health. This study utilized more precise indicators of body fat distribution, including trunk fat mass, limb fat mass, total fat mass and body fat percentage, to investigate their associations with biological aging. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) 2015-2018 was analyzed. A weighted linear regression model was employed to analyze the relationship between body fat characteristics and phenotypic age (PhenoAge). A restrictive cubic spline curve was used to explore potential non-linear relationship. Subgroup analysis and mediation analysis were conducted. Mendelian randomization (MR) analysis was performed using genome-wide association study (GWAS) data. RESULTS: All body fat distribution indicators were positively correlated with PhenoAge, with trunk fat mass exhibiting the strongest association. Subgroup analyses revealed significant correlations across genders, age groups, and BMI categories. Mediation analysis identified C-reactive protein, the systemic immune-inflammation index, and the triglyceride-glucose index as partial mediators. MR analysis supported a causal relationship between body fat distribution and PhenoAge. Additionally, two-step MR analysis suggested a potential role of gut microbiota in linking body fat distribution and aging, while diet targeting gut microbiota diversity may mitigate the effects of body fat on aging. CONCLUSION: This study highlights the importance of body fat management, particularly trunk fat, in aging prevention strategies. Optimizing dietary patterns to enhance gut microbiota diversity represents a promising approach to delaying biological aging.