Critical Reviews in Oncology/hematology · Oct 24, 2026

"Metabolic Diets and Fasting in Oncology: Integrating Guideline-Based Nutrition, Nutrition Assessments and Biomarker-Driven Clinical Pathology"

By Abbasi N

Popular narratives often promote "special diets" as strategies to cure cancer, frequently invoking autophagy and Nobel-related discoveries. In contrast, international oncology nutrition guidelines state that no diet has been proven to reproducibly cure cancer. This review integrates guideline-based oncology nutrition, experimental metabolic diets and a biomarker-driven clinical pathology perspective within a translational framework. This narrative review synthesizes international and national oncology nutrition guidelines and clinical evidence on fasting, fasting-mimicking diets, time-restricted eating, intermittent fasting, Ramadan fasting and ketogenic diets in cancer. Priority was given to randomized and prospective trials, systematic reviews and selected mechanistic studies, with attention to nutritional risk, toxicity, metabolic and inflammatory markers, body composition, cachexia staging and pathological response. Current guidelines discourage restrictive diets outside evidence-based care and recommend early nutritional screening and stepwise nutrition support. Clinical studies suggest that fasting-related regimens and ketogenic diets may improve selected metabolic, hematological, quality-of-life and pathological endpoints in carefully selected patients, but reproducible survival benefit has not been established. Cachexia-oriented models indicate that cancer-related nutritional decline is multidimensional and partly integrates biochemical, inflammatory, functional and patient-reported domains. Mechanistic studies support plausible effects on autophagy, nutrient-sensing pathways, ketone metabolism, inflammation and the tumor microenvironment. The evidence supports a clear distinction between guideline-based oncology nutrition, which is fundamental supportive care, and metabolic diets or fasting regimens, which remain experimental adjuncts rather than curative treatments. The translational opportunity lies in embedding these interventions within malnutrition-, sarcopenia- and cachexia-aware frameworks and using biomarkers to improve risk stratification, patient selection and mechanistic interpretation.

doi.org/10.1016/j.critrevonc.2026.105669PubMed 42926076Interventions