Fasting During Cancer Treatment. Is It Safe?

October 6, 2016
Greg Guthrie, ASCO staff

Annette Goldberg, MS, MBA, RDN, LDN, is an Outpatient Oncology Dietitian at the Boston Medical Center Cancer Care Center. Suzanne Dixon, MPH, MS, RDN, is a Registered Dietitian and Epidemiologist, with a nutrition and research consulting business in Portland, Oregon.

There are a lot of mixed messages when it comes to fasting and its relationship with cancer treatment and prevention. share on twitter  In this podcast, registered dietitians Annette Goldberg and Suzanne Dixon give their expert insights on what fasting is, its use during cancer treatment, when fasting may be helpful, and who should avoid fasting.

  • What exactly is fasting? Find out exactly what “fasting,” “intermittent fasting,” and “calorie restriction” mean [4:20]. Annette Goldberg also describes popular fasting diets, such as the fast-mimicking diet (FMD) and 5:2 diet [5:57].

  • What is the reasoning behind fasting during cancer treatment? When someone fasts, healthy cells stop expending energy to grow and instead direct that energy to protect themselves. The theory behind fasting in cancer treatment is that cancer cells can’t stop growing and are therefore more vulnerable to chemotherapy. There is currently not enough evidence from studies in humans to be sure that this is the case [7:46].

  • Who should avoid fasting? It’s important to remember that you should never begin fasting or make any other changes to your eating unless you have approval from your doctor beforehand. Suzanne Dixon also describes other situations where patients should avoid fasting [10:02].

  • What should you do if you do get clearance to fast from your doctor? Get a referral to a registered dietitian before you begin. Stay hydrated [13:05].

  • Some cancer types can affect a person’s metabolism. People with certain types of cancer have different things to think about when it comes to making a decision about fasting [14:20].

This is a prerecorded audio podcast, and it can be listened to online or downloaded to your computer. A transcript of this podcast is also available. For more information, visit the Cancer.Net podcast page.


Share your thoughts on this blog post on Cancer.Net's Facebook and Twitter.