# Joint Association of Diet Index for Gut Microbiota and MVPA With Central Obesity: The Mediating Role of Biological Age

## TL;DR

A study found that better gut-friendly diets and enough physical activity together reduce central obesity, partly by slowing biological aging.

## Contribution

The study reveals that gut microbiota-targeted diets and MVPA jointly reduce central obesity, with biological aging as a mediator.

## Key findings

- Higher DI-GM scores and adequate MVPA reduce central obesity prevalence by up to 40%.
- Biological age mediates 20-22% of the protective effect of DI-GM on central obesity.
- The protective effects are stronger in females, college-educated individuals, and those with 7-8 hours of sleep.

## Abstract

This study examined the independent/joint effects of diet‐gut microbiota (DI‐GM) scores and moderate‐to‐vigorous physical activity (MVPA) on central obesity and mediation via biological aging. Using NHANES 2007–2018 data (17,012 adults), DI‐GM scores and MVPA (MET‐minutes/week) were assessed. Central obesity was defined as BMI ≥ 25 + waist‐height ratio ≥ 0.5. Biological age was measured via Klemera Doubal Method (KDM), phenotypic age (PA), and homeostasis disorder (HD). Multivariable logistic regression and mediation analyses evaluated associations. Each 1‐point DI‐GM increase reduced central obesity prevalence by 9% (OR = 0.91, 95% CI, 0.89%–0.94%, p < 0.001). Meeting MVPA recommendations (≥ 600 MET‐min/week) lowered prevalence by 18% (OR = 0.82, 0.71%–0.94%, p < 0.001). Participants with DI‐GM ≥ 6 + adequate MVPA had maximal risk reduction (OR = 0.60 vs. DI‐GM ≤ 4 + inadequate MVPA, 0.49%–0.75%, p < 0.001). Biological aging mediated 20.12% (KDM), 22.63% (PA), and 1.68% (HD) of DI‐GM's protective effects (p < 0.05), but not MVPA's effects. Stronger associations occurred in females, college‐educated individuals, and those with 7–8 h sleep (p‐interaction < 0.05). Higher DI‐GM scores and adequate MVPA significantly reduced central obesity prevalence, partially mediated by slower biological aging. Integrating gut microbiota‐targeted diets with physical activity may enhance obesity prevention.

This study found that higher dietary index for gut microbiota (DI‐GM) scores and adequate moderate‐to‐vigorous physical activity (MVPA) were both independently associated with lower central obesity prevalence. Participants with both high DI‐GM (≥ 6) and recommended MVPA showed a 40% reduced risk of central obesity. Biological age partially mediated the association between DI‐GM and central obesity, highlighting the role of gut microbiota‐related dietary patterns in metabolic health.