Therapeutic Fasting / Intermittent Fasting
Therapeutic fasting starves cancer cells by depleting glucose and growth factors (IGF-1, insulin), while simultaneously protecting normal cells through cellular stress resistance. Dr Valter Longo's research shows that 48–72 hour fasting before chemotherapy protects normal cells (differential stress resistance/sensitisation — DSRS) while sensitising cancer cells to treatment. Intermittent fasting (16:8) and the Fasting Mimicking Diet (FMD) are more sustainable approaches with documented anti-cancer effects.
Mechanism of Action
Fasting drops insulin and IGF-1 (cancer growth signals), activates AMPK (energy sensor that inhibits cancer growth pathways), and induces autophagy (cellular self-cleaning). Normal cells enter a protected 'maintenance mode' under nutrient deprivation; cancer cells, locked into high-growth oncogene-driven signalling, cannot downregulate and are more vulnerable to the same stressor. This differential stress sensitisation is the basis of fasting-mimicking protocols around chemotherapy.
Cancer Types Studied
Protocols & Dosing
Peri-Chemotherapy Fasting (Longo Protocol)
48 hours water-only fast before chemotherapy, resume eating 24 hours after infusion. Clinical trials show 40–50% reduction in chemotherapy side effects and improved tumour response. Must be medically supervised for extended fasts.
Fasting Mimicking Diet (FMD)
5-day low-calorie protocol: Day 1: 1090 kcal (10% protein, 56% fat, 34% carb); Days 2–5: 725 kcal (9% protein, 44% fat, 47% carb). Repeat monthly. Available as ProLon kit or DIY.
16:8 Intermittent Fasting
Eat within an 8-hour window, fast 16 hours. Most sustainable long-term. Close eating window by 6–7 pm (circadian alignment). Even 13-hour overnight fasting reduces breast cancer recurrence (27% reduction in NHANES data).
NIH / PubMed Research
Links open on PubMed (National Library of Medicine). Research is ongoing — results may not reflect clinical use.
Cautions & Contraindications
- Extended fasting (>24 h) in underweight or cachexic patients is dangerous — avoid
- Must maintain adequate hydration with electrolytes during fasting
- Diabetic patients: close monitoring required — fasting causes significant blood sugar drops
- Do not fast if on insulin or glucose-lowering medications without medical supervision
- Discuss with oncologist before peri-chemotherapy fasting — some protocols specifically contraindicate
- Not suitable for patients with eating disorder history
Informational only. Not medical advice. Consult your oncologist before starting any alternative or integrative therapy.