Background <p>The Planetary Health Diet proposed by the EAT–Lancet Commission aims to promote global health and environmental sustainability through a predominantly plant-based, carbohydrate-rich nutritional model. Despite its appeal, its universal application raises concerns regarding human metabolic compatibility, nutrient sufficiency, and evolutionary coherence.</p> Objectives <p>This article critically evaluates the Planetary diet through the lenses of evolutionary biology, clinical nutrition, cancer metabolism, and anthropological diversity. An alternative framework is proposed: The autogenous diet, which aligns more with human physiological and ecological heritage.</p> Methods <p>A narrative synthesis was conducted of peer-reviewed literature from evolutionary nutrition, clinical trials, oncology, and chronobiology. Comparative analysis highlights the metabolic divergence between high-carbohydrate, standardized diets and fat-adapted, ancestral nutritional models.</p> Results <p>The planetary diet fails to meet several human biological requirements. It neglects nutrient-dense animal foods rich in DHA, vitamin B12, and bioavailable iron; promotes chronic glycemic load and insulin signaling; and ignores interindividual genetic and epigenetic variability. By contrast, the autogenous diet contains a species-appropriate macronutrient distribution (moderate protein, high fat, low carbohydrate), prioritizes local and minimally processed foods, aligns with circadian biology and fasting cycles, and elicits tumor-suppressive mechanisms.</p> Conclusion <p>The universalization of the planetary diet represents a biological and cultural oversimplification. Nutritional strategies must account for evolutionary metabolism, regional diversity, and clinical outcomes. Ancestral, autogenous diets may offer a more effective and ecological solution that can meet nutritional requirements based on fundamental physiology.</p>