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72 HR fasting before and after chemotherapy

Hi folks,

Breast cancer gal here and will be starting chemo eaear May. Drugs tbc  this week his been told 6 X infusions every 3 weeks, start hormone therapy during cheno too.

Been reading a lot about fastibg - 48 hrs before chemo and 24 hrs after and how this can help alleviate side effects and help body protect itself from killing all the good stuff than bad ( awful scientific analogy but you get my drift). Big believer in time restricted eating but this was to control my weight whereas this is s whole new world. It must help with potential overeating or csca beige food munchies too. I'm terrified when I read about ladies gaining 3 stone on chemo from eating like mad on steroids and " what they fancy" not only on appearance but from a body fuel build from inside out this can't be good. Fasting may help this as well as orotect cells.

Will  of course ask my onco as there seems to be more research done in the last few years than just on mice as in earluer posts .generally the view from health professionals try it as it won't hurt but wobderiww if anyone else tried this. 

Thanks in advance,


  • Hi,

    Please talk to your care team before making a decision, this idea contradicts the advice I was given when I started chemo. There are many different types of chemo I know but starving yourself before and after could make the side effects worse and more importantly it could weaken your immune system and leave you vulnerable to infection.


    Best wishes



  • Hi, I'm on fec for breast cancer, and chatted to my chemo nurse ref fasting, although she had heard of it she said no one had come back to her to say it had worked for them. I know of a lady on my chemo forum who tried it on 2 of her cycles and it was a complete disaster ( vomiting/ nauseous) she is now eating sensibly and doing better...

    personally it's not for me, my appetite is up and down, so if I get an urge for something I have it....chemotherapy is hard enough without worrying about my weight, I simply want to get through it as best I can, then when the time is right I will address any weight issues....


    good luck....will be interesting to find out how you get on xx

  • Thanks for your reply. To clarify this isn't for weight management more to lessen the side effects. 

    Spoken to one person they said it helped just wanted to check with others



  • Hello mumai

    I have only had my first cycle of fec-d for stage 3 grade 3 ductal carcinoma so I cannot compare fasting to non fasting   I fasted for 48 hours before and 24 hours after and I seem to have come off very well with regard to side effects 

    I had some mild nausea but no sickness. No other real symptoms other than tiredness.not worse than the common cold 

    I will definitely be doing it next time

    Look up the work of professor valter longo at University of southern California who explains well the rationale behind the fasting 

    I wish you all the best for your treatment and for me this has been a great addition to the arsenal of weapons we need to combat this nasty disease

  • Thanks so much for your reply. Yep been looking up prof longo. The concept of fasting seems ansurd or unnecessary stress on the body to some but I'm fascinated by the effects on cells and the relievibg of the chemo SE. 

    I'm due to start April 30/ may 1st so will give it a go. Will enjoy the easter eggs first before I go dairy free

  • Hi Mumai 

    I think the subject of fasting during chemo is very interesting. My husband did a lot of research into it when his mum was diagnosed with bowel cancer 6 years ago, Dr Valter Longo has performed many studies and advocates fasting for longevity for all and for cancer patients. My mother in law water fasted for 5 days through 7 of her 9 chemo cycles and suffered very little side affects and has now been cancer free for 5 years. Whether it was the fasting or not I suppose we will never know but it certainly did her no harm. 

    On the flip side when I was diagnosed with stomach cancer in August I decided to try and fast through chemo, my first cycle did not go well and I was rushed to hospital after collapsing, whether I just wasn’t strong enough or the chemo too toxic (it’s a particularly harsh regime) I don’t know but I didn’t try again, my potassium levels had dropped and I was very ill. 

    I would say there’s certainly no harm in trying but know that it’s ok to stop, do what your body tells you to. 

    Good luck


  • Hello everyone

    The Moderators asked if we could add anything to this discussion.  There is some genuine scientific interest interest in seeing if fasting might be helpful during cancer treatment.  But there needs to be much more research done before it is established if it really does make a difference and in what cancers and with which treatments.  As you can see from Louise's post, it might have contributed to her becoming ill during her treatment.  So always check with your doctor before making any significant changes to your diet, or lifestyle during treatment. 

    I hope that helps


  • Thanks martin. Wise words. I'm going to speak to my oncologist about it this week 

    It's becoming a big research area so wanted to get abyobesa experience but the docs and BC nurses opinions are paramount to the decision to try or not to try . specifically for breast cancer in my case.

    Thanks again all


  • Hi  I'm triple neg BC.  No lump just a shadow.  Two surgery attempts to check out nodes and at 5th stage fec-t. One to go I hope!  This week has been the ultimate in side effects.  Reduced % ot treatment to head off side effects. One sepsis admission due to scarry reduced immunity.  Brilliant care and confident with judgement of all support team.  I have not suffered any sickness or bowel issues at all.  Fatigue is my issue.  As if I have a hangover, partcularly  this time. Weight loss minimal but appetite terrible. BP fluctuates. I think I may  go into 48 hour reduction mode pior to chemo of my own accord without much damage over the whole of the course.  Time will tell.  After week 1 I seem to regain strength/stamina. I'm told I have a very poistive attitude and was 'fit' before surprise diagnosis. Hang in there.

  • Hi there!

    I was happy to read about others trying out this option, although I agree it is vital to have your health team on board.

    So far I have tried fasting two out of three cycles and found that the difference in side effects has been considerable. I didn't need any of the meds they send you home with, just had a week of fatigue. BUT, I did have a fever the day after each session and ended up in A&E last time. The fever goes down as soon as I break fast and start eating, so I suspect a link and will probably not fast next time, even though it really bugs me that I will have to put my body through the side effects again. But I am a skinny one and guess my body can only take so much.

    Not sure this is actually useful, just sounds like someone experimenting slightly irresponsibly. But it did give me a sense of being able to do something to help my body and I had a great few weeks with plenty of energy for my toddler. I do hope more research comes through soon improving knowledge on how to use fasting to patients' benefit.