Tuesday, 3 January 2017

Fasting during chemo cycles?

Hi all,

As there is some evidence in mice studies that fasting can be beneficial during chemo cycles, both sensitizing the tumor cells and protecting the regular cells I'm wondering if anyone here has tried it?

If yes, would you be willing to share your experiences?

How long time did you fast? Did you see any direct benefits? Any negative effects? How easy was it to tolerate fasting while taking chemo?

Grateful for any feedback.



  1. Fasting during 5-day periods of cyclic chemotherapy may be doable, but there's reason to suspect that a ketogenic diet may convey the benefits without the starvation. See:
    Tumor Metabolism, the Ketogenic Diet and β-Hydroxybutyrate: Novel Approaches to Adjuvant Brain Tumor Therapy.

    My wife's been on a ketogenic diet since May, when her GBM was diagnosed. We were quite strict with avoiding carbs during the six-week period of radiation+temozolomide. We've gotten a bit more liberal since then, but still avoiding sugars and starches for the most part.

    I think the preclinical data are compelling enough to suggest that most folks with GBM should probably stay on a ketogenic diet.

    One's taste preferences shift over time to accomodate such changes in diet. Most people don't experience much of a sense of deprivation.

  2. I concur with Steve on the Ketogenic or ketogenic type diet during radiation/TMZ treatments. During my radiation/TMZ treatments during 2015, I followed an moderate ketogenic type diet (very limited carbs, high protein and no sugar). Now with maintenance cycle of TMZ done, I have expanded my diet to more of an Adkins type diet (low carb and no sugar)

    Plus taking Metformin then and now.


  3. We tried doing the ketogenic diet during the initial radiation and TMZ but my husband found it very difficult even when I cooked special recipes. He found that his taste buds really changed and a lot of stuff tasted too rich or like dirt. Even though we have done paleo and vegan all before his diagnosis he has never lost his taste for carbs and sugar. Overall though he has not been eating a lot of calories and I know there are cases made for a restricted calorie diet. We are going to begin his first round of adjuvant chemo and are going to give fasting a try. I am trying to decide which pills and supplements to take in conjunction as many upset his stomach such as Metformin. Any suggestions? I know some are supposed to help TMZ work better. He is unmethylated.

  4. I fasted on a number of rounds during chemo and am actually more positive about using it with radiation.

    I did 4-5 day water fasts for most rounds. In general when fasting I didn't need any anti-nausea pills and I rebounded very quickly and less so when not fasting. Overall I found it suprisingly tolerable and mainly just didn't sleep quite as well and was of course a bit weak feeling. Had to really make myself drink enough water though to stay hydrated. I got some hunger pangs on the second day, but by far the hardest part was mental -- if I was at home and bored I would really start to desire some food. Not actual hunger, but more like a desire for a treat. If I managed to resist it would get better, if I cheated even a bit it would get worse.

    I reduced supplements a bit during fasting. The big unknown is that its likely liver clearance of drugs (supps or chemo) is being affected by fasting. So could either help or hurt the amount that makes it into the cancer cells. Many of the theoretical advantages of fasting relate to 'differential stress' where healthy cells will lower metabolism and increase chemo clearance and cancer cells won't down regulate and will have added stress due to glucose restriction. In hindsight, for me with a lower grade tumor it may have been less of a good idea since my regular cells vs cancer cells are not that metabolically different and so if I didn't really add that much metabolic stress, but did increase liver clearance then overall it may have been a bad choice.

    Couple items to keep in mind:

    1) Mouse to humans will roughly correlate 7x. So if looking at a mouse study showing benefits of a 3 day fast, thats 3 weeks in humans!
    2) Fasting definitely relates to ketosis and it usually takes 2-3 days of pure water fasting to burn off stored glucose before you would fully enter ketosis.
    3) If doing a longer keto diet consider getting ketone and glucose test strips with something like the Precision Xtra meter. Staying in ketosis with diet is not too hard, but it is very surprising what things will spike your glucose and its very individual (for me dairy fats turned out to be a major issue). So actually reducing glucose spikes is fairly hard.

    Another thing to consider is that some of the newer research is showing many gliomas already strongly metabolize fats/fatty acids (acetate metabolism/ketone bodies) and have upregulated that pathway. So the Warburg principle of cancer being addicted to glucose is only partly true. So not only is it rather difficult to maintain glucose levels low enough in your brain (vs the rest of the body) to 'starve the cancer', it is also looking more complex as to whether ketosis does indeed limit glioma metabolism over long periods or not. Combo strategies of ketogenic plus RT or chemo would seem more promising though.