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
recommendations ›

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

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

Articles on fasting ›

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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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Keep reading about fasting or calorie restriction


Nancy Hepp, MS

Lead Researcher
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher


Susan Yaguda, MSN, RN

Manager at Atrium Health’s Levine Cancer Institute and CancerChoices Clinical Consultant
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Susan Yaguda, MSN, RN, has been a nurse for nearly 40 years, working in a variety of healthcare settings. She currently works in Charlotte, North Carolina, at Atrium Health’s Levine Cancer Institute as the manager for Integrative Oncology and Cancer Survivorship. She works with a multidisciplinary team to deliver holistic, evidence-based support and education for patients and care partners at any point along the trajectory of cancer care. She completed the Integrative Oncology Scholars Program through the University of Michigan in 2020, is certified as an Integrative Health Coach through Duke Integrative Medicine and has a post-graduate certificate in Nursing Education from the University of North Carolina, Charlotte. Susan also was awarded the Planetree International Scholar’s Award in 2018 and was recognized by the Daisy Foundation for Nurse Leadership in 2021. Susan has a particular interest in empowering patients and care partners with knowledge to help drive informed decision making and educating nurses on the benefits of integrative care for patients and self-care. She has presented nationally and internationally on integrative oncology and nursing education.

She and her husband, Mark, have two adult children and a very spoiled foxhound. She enjoys hiking, knitting, cooking, and pickleball.

“As a frequent consumer of Beyond Conventional Cancer Therapies, and now CancerChoices, for both professional education and patient support, it is an honor to have the opportunity to engage with the dedicated team at CancerChoices to serve those impacted by this disease.”  


Susan Yaguda, MSN, RN Manager at Atrium Health’s Levine Cancer Institute and CancerChoices Clinical Consultant

Last update: May 9, 2024

Last full literature review: April 2023

We are grateful for research support from Dr. Irfan Siddique and Adriana Gutierrez Galvis.

CancerChoices provides information about integrativein cancer care, a patient-centered approach combining the best of conventional care, self care, and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocialtherapy, and acupuncture therapies and self carelifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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