Background Obesity and type 2 diabetes mellitus (T2DM) are associated with accelerated brain atrophy, white matter microstructural disruption, and resting-state functional network dysconnectivity in elderly adults, driven by converging vascular, neuroinflammatory, and insulin-resistance mechanisms. Yoga is a recognized mind-body intervention with documented benefits for glycaemic control, vascular health, and neurocognitive function; however, no study has yet employed multimodal MR neuroimaging to systematically characterize these brain alterations in an elderly obese-diabetic population or to evaluate yoga-induced neuroplasticity within this cohort. Methods This three-phase, prospective protocol will be conducted at Kasturba Hospital and the Center for Integrative Medicine and Research, Manipal Academy of Higher Education, Manipal, India. Phase 1 is a case-control study (n = 80; 40 obese-diabetic, 40 obese-non-diabetic; age 60–80 years) employing carotid Doppler ultrasonography, T1-weighted voxel-based morphometry and region-of-interest segmentation (SPM12/CAT12/AAL3), diffusion tensor imaging with ROI-based tractography (ExploreDTI), and resting-state fMRI (CONN toolbox), alongside the Eriksen Flanker and N-Back cognitive tasks. Phase 2 involves the systematic development and expert content-validation of a structured, AYUSH-compliant yoga module tailored for elderly obese-diabetic adults. Phase 3 applies the validated module in a 6-month pre-post intervention, with objective adherence monitoring via triaxial accelerometry and repeat of the full Phase 1 neuroimaging and cognitive battery. Discussion This protocol addresses a critical gap in the yoga-neuroimaging literature by providing a multimodal, multi-phase framework to characterize neurovascular disease burden and evaluate structured yoga as a neurobiologically informed lifestyle intervention in a high-risk elderly population. Findings will inform AYUSH clinical guidelines, geriatric NCD prevention programs, and future randomized controlled trials.