Socioeconomic Differentials in Underweight and Its Association with Self-Rated Health, Cognition and Quality of Life among Tribal Older Adults in Rural Assam, India: A Cross-Sectional Study

Background: Undernutrition is a health problem among older adults, especially in rural tribal communities. This study examined socioeconomic patterns of underweight and its association with self-rated health, cognition, and quality of life among tribal older adults in rural Assam, India. Methods: A community-based cross-sectional study was conducted among 1,160 tribal adults aged ≥50 years from Mishing, Sonowal Kachari, and Deori communities between February and June 2025. Multistage purposive sampling was used. Body mass index was calculated from measured height and weight using Asia-Pacific WHO cut-offs. Socioeconomic status, self-rated health, cognitive function, and quality of life were assessed using standardized measures. Regression models examined associations between BMI and health outcomes. Results: 36.55% participants were underweight, 51.47% had normal weight, 7.76% were overweight, and 4.22% had class I obesity; no participant had class II obesity. Underweight was more common with increasing age, lower socioeconomic status, less education, non-married status, and among Deori participants. Compared with normal-weight participants, underweight was associated with higher odds of poor self-rated health (OR 2.12, 95% CI 1.87-2.52), lower cognitive scores (β -1.88, 95% CI -2.11 to -0.76), and lower quality-of-life scores (β -2.20, 95% CI -2.60 to -1.82). Conclusion: Underweight is prevalent among rural tribal older adults in Assam and is associated with poorer physical, cognitive, and quality-of-life outcomes. Socioeconomic and nutritional vulnerabilities warrant integrated geriatric interventions.