Isocaloric substitution with beef and mutton and metabolically unhealthy obesity among adults in Ordos, Inner Mongolia: a cross-sectional analysis.

BACKGROUND: Metabolic health differs substantially among adults with obesity, and dietary structure may contribute to this heterogeneity. In Ordos, Inner Mongolia, beef and mutton are common food sources within a livestock-oriented dietary setting rather than merely generic red-meat exposures. METHODS: We analyzed 1,103 adults with obesity from the 2024 Ordos Region Residents' Health White Paper survey. Dietary intake was assessed using an 83-item region-specific semi-quantitative food-frequency questionnaire and expressed as the percentage of total energy intake from 16 mutually exclusive food groups. Associations with metabolically unhealthy obesity (MUO) were evaluated using multivariable logistic regression, restricted cubic splines, and all-components isocaloric substitution models. RESULTS: Overall, 440 (39.9%) were classified as metabolically healthy obesity (MHO) and 663 (60.1%) as MUO. In fully adjusted models, beef and mutton intake was inversely associated with MUO (OR per 5%E = 0.821, 95% CI: 0.719-0.933; p = 0.003). Compared with participants in the lowest quartile, those in the highest quartile of beef and mutton intake had lower odds of MUO (OR = 0.581, 95% CI: 0.394-0.856; p-for trend = 0.017). Restricted cubic spline analysis suggested an approximately linear inverse association (p-overall = 0.013; p-nonlinearity = 0.938). In theoretical substitution models, replacing selected food groups with beef and mutton was associated with lower odds of MUO. Dairy intake showed a weaker and less consistent inverse association. CONCLUSION: Among adults with obesity in Ordos, higher dietary energy from beef and mutton within the regional dietary structure was associated with lower odds of MUO in selected modeled substitution contrasts. These context-specific, cross-sectional findings require confirmation in prospective studies.