Calorie restriction and fasting, whether for 12 or more hours every night or occasionally for longer periods, can contribute to lower body weight, blood sugar, and insulin resistance, plus fewer unpleasant chemotherapy-related side effects.
How do experts use fasting or calorie restriction?
Integrative experts provide recommendations for fasting or calorie restriction in treating people with cancer. Learn more about the approaches and meanings of
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Published protocols, programs, and approaches
These protocolsa package of therapies combining and preferably integrating various therapies and practices into a cohesive design for care, programs, and approaches by leaders in integrative cancer care use or recommend fasting or calorie restriction.
We do not recommend specific integrative protocols or programs but provide information for you to evaluate with your healthcare team.
Lise Alschuler, ND, FABNO, and Karolyn Gazella
Alschuler LN, Gazella KA. The Definitive Guide to Cancer, 3rd Edition: An Integrative Approach to Prevention, Treatment, and Healing. Berkeley, California: Celestial Arts. 2010.
Alschuler LN, Gazella KA. The Definitive Guide to Thriving after Cancer: A Five-Step Integrative Plan to Reduce the Risk of Recurrence and Build Lifelong Health. Berkeley, California: Ten Speed Press. 2013.
Naturopathic oncologist Lise Alschuler, ND, recommends overnight fasting for 13 hours, as this has been associated with improved survival after a diagnosis of breast cancer. For instance, you could finish dinner at 7pm and eat nothing else until 8am the next morning when you “break fast.” In addition, for people having significant side effects, especially gastrointestinal, from chemo, Dr. Alschuler may also recommend fasting for 48 hours—from after dinner on the day before chemo, through the day of chemo and the day following chemotherapy. The chemo fast can be a water fast (which includes coconut water and vegetable broths), or you can eat up to 600 calories per day of vegetable soup and/or low-carb vegetables. She stresses the importance of your being motivated to fast, and also that fasting during chemotherapy should be cleared with your treating oncologist. You should modify or stop the fast if you become dizzy or weak (try adding boiled eggs or nuts), or if you feel worse than if you had eaten.
Keith Block, MD, Penny Block, PhD, and Charlotte Gyllenhaal
Block KI, Block PB, Gyllenhaal C. Integrative treatment for colorectal cancer: a comprehensive approach. Journal of Alternative and Complementary Medicine. 2018;24(9-10):890–901.
“Patients who have low BMI, who have lost more than 10% of body weight, or who do not regain at least 25% of weight loss between treatment cycles should not fast.”
Barbara MacDonald, ND, LAc
MacDonald B. The Breast Cancer Companion—A Complementary Care Manual: Third Edition. Self-published. 2016.
Naturopathic physician Barbara MacDonald provides information about breast cancer, its conventional treatment, and natural approaches to enhancing treatment, managing side effects, reducing risk of recurrence, and healthy living after cancer treatment is completed.
“There is a lack of human data on this subject. It may be worth trying in patients experiencing severe side effects to chemotherapy as long as calorie restriction is not contraindicated for other reasons.”
Neil McKinney, BSc, ND
McKinney N. Naturopathic Oncology, Fourth Edition. Victoria, BC, Canada: Liaison Press. 2020.
This book includes descriptions and uses of many natural and complementary protocols for cancer in general and for specific cancers. It also includes information on integrative support during conventional cancer treatment.
Uses of fasting:
- Just before and right after chemo
- Periodic fasting for positive health effects
Gurdev Parmar, ND, FABNO, and Tina Kaczor, ND, FABNO
Parmar G, Kaczor T. Textbook of Naturopathic Oncology: A Desktop Guide of Integrative Cancer Care. 1st edition. Medicatrix Holdings Ltd. 2020.
This book provides information on the treatment of 24 cancers, plus the most effective treatments of the most common symptoms affecting cancer patients while they undergo chemotherapy, radiotherapy, or surgery.
This protocol discusses types of fasting as well as the evidence on fasting for prevention of cancer, time-restricted feeding, a fasting-mimicking diet, and fasting during treatment, plus precautions/contraindications to fasting in cancer care. The authors note that “for those who are capable, entering a ketogenic state through diet or fasting during chemotherapy or radiation may be a useful tool that is low-cost and may lessen the risk of side effects during treatment.”
Nasha Winters ND, FABNO, LAc, DiplOM, and Jess Higgins Kelley, MNT
Winters ND, Kelley JH. The Metabolic Approach to Cancer. 2017. Chelsea Green Publishing.
This book’s metabolic approach to cancer is a “naturopathic nutrition program that uses the medicinal powers of traditional foods, therapeutic diets and non-toxic lifestyle approaches as cancer counteragents and preventives.“ The program focuses on 10 terrain elements and how to assess them and bring them into balance.
Uses of intermittent fasting and/or calorie restriction:
- Therapeutic fasting and calorie restriction to reduce toxic burden and cancer growth
- Fasting to reboot the metabolic immune system
- Fasting to stabilize and reverse cachexiaweakness and wasting of the body due to severe chronic illness
- Fasting and calorie restriction to reduce free radicals and reduce mitochondrial metabolic activity
- Fasting to reduce IGF-1 (insulin-like growth factor)high levels of IGF-1 are associated with increased risk of some types of cancer whereas some of IGF’s binding proteins (IGFBP’s) seem to be protective; high intakes of dietary protein, especially animal and soy protein, appear to increase IGF-1 levels and sensitize cells to chemotherapy
- Fasting combined with hyperbaric oxygen to produce antitumor effects
- Fasting to help reset circadian rhythms
Other expert assessments
Moss Reports
The Moss Reports conclude that a calorie-restriction diet is effective in improving body terrain and reducing some side effects of chemotherapy. Intermittent fasting is linked to lower risk of cancer or recurrence and better body terrain.
Dwight McKee, MD
Dr. Michael Ruscio, DC, noted that Dwight McKee, MD, recommends fasting: Fasting dramatically reduces toxicity. “I have had some patients who nearly died from their first cycle of treatment, but then fasted for three days with their second cycle and breezed through it.” However, fasting is not recommended for people dramatically underweight who are not able to regain weight by the next cycle.1Ruscio M. Integrative Cancer Care—Extremely Helpful Tips from Leading Expert Oncologist Dwight McKee. Dr. Ruscio DC. August 2018. Viewed July 5, 2023.
Brian Bouch, MD
CancerChoices advisor Brian Bouch, MD, explains the benefits of fasting before chemotherapy.
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