Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder characterized by impaired glucose metabolism, mitochondrial dysfunction, inflammation, oxidative stress, and progressive cognitive decline. Because currently available pharmacological therapies provide only modest symptomatic benefit, nutrition-based interventions are increasingly being explored as complementary strategies for supporting brain metabolism and cognitive resilience. The KetoFLEX 12/3 dietary pattern, developed within the ReCODE (Reversal of Cognitive Decline) program, is a plant-rich, mildly ketogenic nutrition and lifestyle framework that integrates low-glycemic nutrition, time-restricted eating, and personalized metabolic optimization. The diet emphasizes deeply pigmented non-starchy vegetables, extra-virgin olive oil, nuts and seeds, omega-3-rich seafood, and minimally processed foods while limiting refined carbohydrates, sugars, processed foods, and selected grains and dairy products. Emerging mechanistic and clinical evidence suggests that KetoFLEX 12/3 may influence several pathways relevant to AD pathophysiology, including insulin signaling, mitochondrial bioenergetics, neuroinflammation, oxidative stress, autophagy, detoxification pathways, and gut-brain axis function. Observational findings from ReCODE-related studies have reported improvements in metabolic parameters, mood-related outcomes, cognitive measures, and brain volumetrics in participants adhering to multimodal precision-medicine interventions incorporating the KetoFLEX principles. Compared with traditional dietary models such as the Mediterranean or MIND diets, KetoFLEX 12/3 places greater emphasis on mild nutritional ketosis, meal timing, and metabolic personalization based on factors such as ApoE genotype and insulin sensitivity. The objective of this Perspective is to examine the mechanistic rationale, emerging evidence, limitations, and future research priorities for KetoFLEX 12/3 as a precision-nutrition framework for cognitive health in AD. Although much of the current evidence remains mechanistic, observational, or derived from multimodal intervention studies, the framework offers a biologically plausible precision-nutrition model that may inform future research and clinical investigation in cognitive decline.