Patient Leaflets — 8/11/2026

Can I Fast During Cancer Treatment?

Cancer treatment can make it difficult to obtain enough calories, protein and fluids.

Questions You're Afraid to Ask

The short answer

Do not begin prolonged or restrictive fasting without discussing it with your cancer-care team.

Cancer treatment can make it difficult to obtain enough calories, protein and fluids.

Why can fasting be risky?

It may contribute to:

Weight loss

Weakness

Dehydration

Malnutrition

The risk may be greater if you already have poor appetite or significant weight loss.

What if fasting is important to me for religious reasons?

Tell your doctor.

Your medical team may be able to help you find a safer approach depending on your treatment and health.

Remember

Research into fasting and cancer is ongoing.

Fasting is not a replacement for cancer treatment.

Your nutritional safety comes first.

This information is intended for education and supportive care. It does not replace consultation, diagnosis or treatment by a qualified healthcare professional. If you have cancer, do not stop, delay or change prescribed cancer treatment because of information found on this website. Tell your cancer-care team about all medicines, Ayurvedic preparations, herbs, vitamins and supplements you use.

Reliable sources: National Cancer Institute (NCI), World Health Organization (WHO), relevant national cancer-care guidelines, and appropriate peer-reviewed evidence.

Dr. Aakash Kembhavi

MD (Ayu-Shalya), PGDMLS, MS (Counseling & Psychotherapy) | Academician, Clinician & Researcher | Chief Editor, International Journal of Ayurveda

Founder of Cancer Support India.