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Several years ago, a study suggested that fasting – avoiding most or all calories – for a short time before receiving cancer chemotherapy may enable the treatment to kill cancer cells more effectively. This study was conducted in mice, not people. We do not know if what happened in mice would happen in people with cancer.

Fortunately, there are several well-designed clinical trials on-going, and these trials are focused on determining whether fasting before, during and/or after chemotherapy or radiation treatment is beneficial. Further, these trials should help us sort out which people, with which types of cancer, are likely to benefit the most from this approach.

Understandably, people living with cancer do not want to wait for clinical trial results for an answer. They have cancer today, and for obvious reasons, many of these people are interested in trying fasting now.


What’s the harm in fasting?

Due to the lack of published studies in humans, it is premature to recommend fasting before chemotherapy or radiation therapy for all cancer patients. However, it is reasonable that people with cancer who are otherwise healthy, well-nourished, and not at risk of developing malnutrition try fasting. But this does not mean every person with cancer should try fasting.

The most important thing to remember is that weight loss and muscle wasting are common problems faced by cancer patients. For people with these concerns, deliberately depriving the body of calories and protein is not a good idea.

In fact, recent research on nearly 1,500 lung and gastrointestinal cancer patients found that weight loss and loss of muscle mass were stronger predictors of survival than even tumor type, stage of cancer, the patient’s age, and how well they functioned in their day-to-day life (performance status) [i].

This points to the importance of addressing unintentional weight loss. This is the type of weight loss that simply “happens,” without the patient trying. Unintentional weight loss occurs even though the person is trying to eat enough to prevent weight loss.

Also key: this study clearly showed that even for people who were overweight or obese, losing weight led to poorer survival. In other words, carrying excess weight does not protect against the negative consequences of unintentional weight loss in people being treated for cancer!

Clearly, fasting is not for everyone.


Should I fast?

Remember, if you are having unintentional weight loss due to cancer or its treatment, fasting may cause more harm than benefit. People with unintentional weight loss have more severe side effects, more treatment dose reductions, and generally poorer survival.

The unintentional (not trying) aspect of weight loss during cancer care is important. People in this situation often are very different, physiologically, compared with patients who are not losing weight unintentionally.

When the body is losing weight without the person trying, it means that person is having more inflammation, more loss of lean tissue, more depressed immune function, and is experiencing many other markers of poor outcomes. For people who are not losing weight unintentionally, the picture is very different.

If a person is losing weight with a healthy diet and regular physical activity (including strength training and cardiovascular activities), the small amount of weight loss that may occur with fasting is not as likely to cause harm. Of course, this should only be attempted during cancer care with the approval of the medical team.

In these cases of weight loss “on purpose,” the benefits of fasting may outweigh the downsides. This type of person is in a better place to tolerate some calorie deprivation without losing healthy, lean tissue.


Why would fasting be good?

Normal cells and cancer (malignant) cells grown in test tubes behave differently under conditions of starvation. When deprived of nutrients, normal cells quickly stop growing and switch into a state of “housekeeping.” They perform only functions that are absolutely necessary for survival. Their growth slows, and they metabolize (use) nutrients at a much slower pace than when nutrients are readily available.

In contrast, cancer cells continue to divide under starvation conditions. In many cases, they grow and divide until they exhaust all nutrients, and then die.

This makes sense: the hallmark (key feature) of cancer cells is uncontrolled growth and replication. This means that regardless of the availability of nutrients, or anything else for that matter, cancer cells just go right on growing and dividing.

Unlike healthy cells, cancer cells don’t have the luxury of slowing down just because nutrients are scarce.

Also of interest is that under starvation conditions, normal cells in a test tube are up to 1,000 times better protected against chemotherapy drugs than cancer cells. This also makes sense.

If normal cells are growing very slowly (or not at all) due to a lack of nutrients, they aren’t going to ‘take up’ or absorb the chemotherapy drugs. This may be one explanation as to why fasting could protect normal tissues against damage during cancer treatment.

To summarize: fasting may protect normal cells against damage, while simultaneously making cancer cells more sensitive to the treatments that are aimed at killing them [ii].


Who is studying the possible benefits of fasting during cancer treatment?

One researcher actively pursuing this line of inquiry is Valter Longo at USC.

Dr. Longo has published a human case series. A case series simply reports what is observed. It is not a true test of whether a particular treatment approach (including fasting) is helpful, harmful, or neutral.

The National Cancer Institute has highlighted the work of Dr. Longo and other cancer researchers who are studying fasting.

A few examples of some of the ongoing clinical trials on fasting can be seen at:

You can see more examples of these trials on the website. Searching on fasting and chemotherapy, fasting and radiation therapy, dietary restriction and cancer, and other, similar combinations of words will yield dozens of examples of on-going clinical trials on this topic.


What to consider with fasting during cancer care

For people who are interested in fasting, there are some very important things to keep in mind:

  • Never attempt fasting without discussing it with your doctor and dietitian. It is in your interest that everyone on your healthcare team is on the same page. Even if your medical team discourages you from fasting, if you plan to do it anyway, do not hide this from them.
  • Do not try fasting if you are taking oral chemotherapy medications. These are cancer drugs that are taken by mouth. Many oral chemotherapy medications must be taken with food, or taken with a very specific amount of calories, fat, protein, or other nutrients, to be absorbed fully, and to work properly. This issue hasn’t received much attention in the debate about pros and cons of fasting during cancer treatment. It is very important!
  • Hydrate, hydrate, hydrate! Fasting does not mean avoiding all liquids. In fact, if you are dehydrated when you receive cancer treatment, this can cause permanent damage to your body. For example, kidneys can be damaged when chemotherapy is given without the person drinking enough fluids. The liver may not detoxify and excrete the chemotherapy properly.
  • Be sure you know what you’re doing and how you plan to fast. To some people, fasting means avoiding all calories, solid and liquid. To others, fasting means cutting way back on what you are eating and drinking, but not going completely without calories. Some people want to fast for 3-5 days, which is a long time! They decide to fast for 1-2 days prior to receiving treatment, the day of treatment, and for 1 day after treatment. Do not do this without talking to your medical team!
  • Do not fast if you have other chronic conditions, such as kidney or liver problems, diabetes, heart disease, or other health issues. Fasting under these conditions may not be safe. Don’t risk your health by trying something that may cause more harm than benefit.
  • Stop fasting if necessary. For nearly all of the research studies on this topic, the researchers have specific guidelines (protocols) in place to address excessive weight loss. If weight loss reaches a certain point, and if the weight isn’t regained, fasting is discontinued. Even the researchers acknowledge that losing too much weight during cancer treatment can be harmful.

Right now, we don’t know if fasting during cancer treatment is a good idea, but early research suggests this approach may be beneficial to some patients.

If you are interested in this, ask your medical team for more information about the pros and cons of fasting during cancer care.


[i] Martin L, Birdsell L, Macdonald N, Reiman T, Clandinin MT, McCargar LJ, Murphy R, Ghosh S, Sawyer MB, Baracos VE. Cancer cachexia in the age of obesity: skeletal muscle depletion is a powerful prognostic factor, independent of body mass index. J Clin Oncol. 2013;31(12):1539-47.
[ii] Raffaghello L, Lee C, Safdie FM, et al. Starvation-dependent differential stress resistance protects normal but not cancer cells against high-dose chemotherapy. Proc Natl Acad Sci USA. 2008;105(24):8215-8220.

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Susan started Savor Health after losing a close friend to a brain tumor and, through that experience, becoming aware of the significant unmet nutritional needs of people with cancer.  Struck by the fact that her friend was told “nutrition doesn’t matter” and “eat whatever you want,” Susan read the evidence-based literature on the subject, interviewed oncologists, oncology nurses and oncology dietitians, as well as patients and caregivers, and found that, in fact, nutrition does matter in oncology. Armed with solid scientific evidence supporting the clinical and quality of life benefits of proper nutrition, Susan left Wall Street and created Savor Health, an AI-based provider of personalized and clinically appropriate nutrition solutions for cancer patients, their caregivers and health enterprises. Susan brings to Savor Health over 25 years of industry experience in healthcare and business as well as expertise in strategy, finance and management.

Susan is an outspoken and tireless advocate for cancer patients receiving proper nutrition and nutrition support before, during and after treatment. She strongly believes that the U. S. healthcare system requires new innovation to transform it into a more holistic and integrated system of care whereby multiple disciplines coordinate care together for the benefit of the whole patient. As part of this, her goal is for nutrition to be an integral component of such an integrated cancer care delivery system.  Susan’s commitment to the field of oncology extends beyond Savor Health to volunteer work at Memorial Sloan Kettering Cancer Center in pediatrics and as a runner for Fred’s Team to raise money for research at Memorial Sloan Kettering. Susan participated in the Cancer Moonshot in June of 2016 where she was a breakout session group “igniter” tasked with starting and leading discussion. Susan’s first book, the Meals to Heal Cancer Cookbook, was published in March 2016.

In addition to her role as CEO of Savor Health, Susan speaks nationally about the importance of ensuring proper nutrition in the cancer patient and on topics including leadership and startups. She has been a speaker at the Harvard Medical School’s Career Advancement and Leadership Skills for Women in Healthcare, ESMO World Congress on GI Cancer, BioPharm America, AARP Live @50+, Lake Nona Impact Forum, and IIR ePharma Summit.

Prior to starting Savor Health, Susan had a successful career on Wall Street as a healthcare services investment banker working at prestigious firms including Donaldson, Lufkin & Jenrette, Wasserstein Perella and Robertson Stephens. Susan earned a B.A. from Duke University and M.B.A. from the University of Virginia’s Darden Graduate School of Business.

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Marissa Buchan is a registered dietitian, with advanced practice certifications in Oncology Nutrition (CSO) and Clinical Research (CCRP). She received her Bachelor’s degree in Psychology from Duke University, and Master’s of Science degree in Clinical Nutrition from New York University. Marissa worked for 10 years at Memorial Sloan Kettering Cancer Center in both the clinical research and nutrition departments.  In addition to counseling patients before, during, and after cancer therapy, she spearheaded nutrition-research efforts for the bone marrow transplant service. She has co-authored over 20 articles and has a particular interest in the role of nutrition on the intestinal microbiota and its impact on patient outcomes. When Marissa’s not wearing her lab coat, she’s in her apron whipping up healthy and delicious recipes that you can find on her blog, Get Off Your Tush and Cook.

Marissa is Chief Operating Officer of Savor Health where she leads operations working with the technology, clinical, and business development teams and management. Prior to assuming the role of COO in March 2020, Marissa was Vice President, Clinical Research and Operations at Savor Health where she worked closely with Savor Health’s Chief Medical Advisor, Scientific Advisory Board, and Clinical Operations Team to evaluate, design and conduct clinical research.  She also counsels patients on oncology nutrition issues and contributes to the Company website’s clinical content.

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Dr. DeFrance has a unique background including clinical interventional cardiologist, chief medical officer, educator, outcomes researcher and entrepreneur. He has expertise in Lifestyle medicine in which he was board certified in 2020 and is highly interested in the prevention and reversal of chronic disease. Dr. DeFrance also has expertise in appropriate utilization of technology in medicine, healthcare economics, value-based metrics, and educational design and delivery. He worked as Chief Medical Officer for HealthHelp, one of the largest specialty benefit managers in the US, and led large teams of healthcare professionals in writing evidence based appropriate care guidelines and rule sets which improve the quality and safety of medicine for over 20 million people in the US while also creating sustained savings in healthcare. He has also designed clinical decision support systems that are currently in use helping to improve patient care.

In 2018 Dr. DeFrance founded MedMentor Education, a company that provides state of the art CME content using the latest in eLearning science and online delivery platforms. Dr. DeFrance is also the founder and President of Digimedica, a consulting and educational design and delivery company for healthcare professionals, hospitals, and universities. He is passionate about creating systems to optimize knowledge transfer and has won numerous awards for teaching excellence during his career. He is an expert in cardiovascular CT imaging and has taught more than 3,000 physicians how to perform and interpret cardiac CT nationally and internationally and has lectured extensively on this subject.

Dr. DeFrance has a stellar reputation in the medical field and continues work to improve the quality and safety of patient care in the US.

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Alyson is a registered nurse and is certified in oncology nursing (OCN) through the Oncology Nursing Society (ONS). She also has her certification as an ONS Biotherapy and Chemotherapy Provider. Alyson studied nursing at Thomas Jefferson University where she obtained her Bachelor’s of Science in Nursing (BSN). Since starting her nursing career in 2004, Alyson has had a strong dedication and commitment to oncology patients. She has worked inpatient specializing in Bone Marrow and Peripheral Blood Stem Cell Transplantation. Alyson currently works in outpatient oncology at the North Shore-LIJ Monter Cancer Center. Alyson is part of the clinical team at Savor Health where she counsels patients on oncology and oncology nutrition issues and contributes to website and other Savor Health content.

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Chelsey is a Registered Dietitian and Board Certified Specialist in Oncology nutrition (CSO). She completed her Dietetic Internship at Northwell Health, received her BS in Dietetics at the University of Wisconsin-Madison, and her MS in Nutrition at Stony Brook University’s School of Medicine. Chelsey works as an outpatient dietitian at Mount Sinai covering all of the downtown cancer services at Mount Sinai Beth Israel and Philips Ambulatory Care Center. Chelsey works with patients and families before, during and after treatment to optimize their nutrition through dietary counseling and support. Chelsey has experience counseling clients with a variety of diagnoses including breast cancer, lung cancer, prostate cancer, head & neck cancer, and more. Chelsey also enjoys sharing nutrition knowledge with her peers by running a monthly Employee Wellness program that showcases healthy topics, recipes and food demos.

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Michelle is a Registered Dietitian specializing in oncology. She works as a clinical dietitian at an ambulatory cancer center in New York City and is a consultant for Savor Health. She is passionate about educating oncology patients on the importance of nutrition during their fight against cancer and helping them to optimize their nutrition through all phases of treatment. Michelle received her Bachelor of Science degree in dietetics from the University of Wisconsin-Madison and her Master of Science degree in Clinical Nutrition from New York University.

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Denise Sievering is a Registered Dietitian who is board certified in Oncology Nutrition as well as Nutrition Support. A fluent Spanish speaker, Denise joined the Savor Health team to support Spanish speaking cancer patients and to continue to expand the Platform’s nutritional strategies and recommendations in Spanish. Denise holds a Bachelor of Science degree from Rutgers University, and completed her internship at New York Presbyterian Hospital (NYP). Denise started her career as a registered dietitian at NYP-Columbia University Medical Center, primarily covering inpatient Oncology units. Denise also holds a Master of Arts degree in Mental Health Counseling from New York University, and incorporates her advanced training in motivational interviewing and empathic listening in her patient encounters, particularly those whose lives have been forever changed by a cancer diagnosis. A New Jersey native, Denise now resides in sunny San Diego, CA where she works as a part-time outpatient Oncology dietitian at Scripps Health-MD Anderson Cancer Center, and also works as an inpatient dietitian at Kaiser Permanente. In her spare time, Denise can be found at a mom-and-pop taco shop, one of the many local craft breweries, and exploring her new city of San Diego with her husband and her rescue pup, Ripley.

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Karen is a Registered Dietitian, Board Certified Specialist in Oncology Nutrition and registered in New York as a Certified Dietitian Nutritionist. Fluent in Spanish, Karen joined the Savor Health team to support Spanish speaking cancer patients and to continue to expand the Platform’s nutritional strategies and recommendations in Spanish. Karen received her Bachelor of Science degree from Ithaca College and her Master of Science degree from Hunter College. She works as an outpatient oncology dietitian in New York. Karen often works with local community centers to host nutrition programs for cancer survivors and their families, leading classes on how to live healthier lifestyles throughout their continuum of care. The American Institute of Cancer Research selected to showcase one of her many programs at their conference in 2019. Karen has written for and lent commentary to various publications and truly enjoys teaching people how to eat better. She loves to cook and strongly feels that healthy food doesn’t have to taste bad.

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Allie is a Registered Dietitian and a Certified Specialist in Oncology (CSO). She joins Savor in 2023, bringing years of experience from the John Theurer Cancer Center in New Jersey, where she worked with patients with a variety of cancers. Her goal is to help people feel their best, both mentally and physically, when physical health challenges arise. She believes in the power of nutrition ever since the impact it made on her athletic career as a volleyball player during college. Allie graduated with her Bachelor of Science degree from University of Maryland-Baltimore County and has her Master’s degree in Human Nutrition from the University of Wisconsin Stout. She enjoys travelling, enjoying different cuisines, cooking, and hiking and other outdoor activities with her family and dog.

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Julia Penberg is a seasoned healthcare professional with more than 30 years of experience focusing on maximizing operational excellence, leading clinical program development and building strong cross-functional teams. Her previous roles include overseeing the performance of clinical managers and nurse practitioners across multiple markets within United Healthcare-Optum’s Medicare Advantage and dual-eligible special needs populations, payer outreach and program development at Mayo Clinic, ground level specialty hospital development and direct patient care as a family and dermatology nurse practitioner. Julia volunteered as an operating room nurse and nurse practitioner on several mission trips to Romania and was a support group leader for the Kansas City chapter of the International Myeloma Foundation. Her motivation throughout her career has been with wellness promotion, disease risk modification and ensuring the best patient experience across the health continuum. Ms. Penberg received an MBA from the University of Dallas; a MS in Nursing from the University of Kansas and a BS in Nursing from the University of Texas-Austin. She is board certified as a Family Nurse Practitioner.

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Rachel is a Registered Dietitian and Board Certified Specialist in Oncology Nutrition (“CSO”). She joined NYP-Columbia as the outpatient oncology dietitian in 2020 after working at Jamaica Hospital Medical Center for two years. Rachel completed her dietetic internship through Keene State College in 2017. She is pursuing an MS in Integrative Nutrition at Stony Brook University and has a BS in Human Nutrition, Foods and Exercise from Virginia Tech. Rachel provides nutrition counseling to all types of oncology patients and helps them understand the mental and physical benefits of nutrition as an ally in their fight against cancer. In her free time she enjoys slow meals with family and friends, Pilates, and tending to her fire escape garden.

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Allie Werner is a Registered Dietitian at Fresenius Kidney Care where she provides medical nutrition therapy diet counseling to patients on Dialysis. She received her Bachelor’s Degree in nutrition from Indiana University and completed her Master’s Degree and dietetic internship at Loyola University Chicago. In her free time she enjoys spending time with friends and family, checking out the amazing food scene in downtown Chicago, and exercising on her Peloton bike.

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Immersed in the tech world for a decade, I've coded, led teams, and honed my skills in architecture and design. As a tech enthusiast, I've seamlessly woven through full-stack projects, fusing my love for code with the art of leadership.

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Mohit is a full-stack developer with expertise in Python and JavaScript, known for his efficient coding and ability to deliver scalable software solutions. His technical contributions are highlighted on GitHub and Stack Overflow, demonstrating his commitment to the tech community and problem-solving skills. With a solid educational foundation and a diverse project portfolio, Mohit excels at navigating complex challenges and is well-equipped to contribute to dynamic software projects.

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Rayna McCann is a Registered Dietitian and Board Certified Specialist in Oncology Nutrition. She is a Registered Yoga Teacher and yoga4cancer certified. She received her BS in Nutrition at Penn State University and her MS from Stony Brook University. For work, Rayna wears many hats in the world of nutrition and worked for years in clinical settings focusing on oncology nutrition. She is also an Adjunct Professor and passionate about inspiring the future of dietitians. Throughout her career, she has received awards recognizing her dedication to patient safety and her contributions to improving malnutrition awareness. In 2022, Rayna was proud to accept the ‘Dietitian of the Year’ award through the Long Island Academy of Nutrition and Dietetics. Rayna has co-authored abstracts for poster presentations within the American Institute for Cancer Research conference, as well as, the Nutrition and Dietetics Food and Nutrition Conference Expo and subsequent publication. She has enjoyed authoring articles, including an article for The Cure magazine regarding Multiple Myeloma and nutrition. When Rayna is not participating in nutrition related activities, she is dedicated to dog rescue.

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