The FastDay Forum

This study by Valter Longo et al has attracted a lot of attention because of the press headlines, especially in the Telegraph, which reported that "Fasting for three days can regenerate entire immune system, study finds".

We are getting quite a few people on the 5:2 Intermittent Fasting Diet Facebook group asking about how to do it! My general advice is that prolonged fasting (i.e. more than 2 days b2b) should only be undertaken with medical supervision, as there are risks such as fainting to be concerned about.

But then I started thinking, that really we have all been prepared to experiment on ourselves with 5:2 based on the initial example of one man getting good results, so maybe I shouldn't be so quick to discourage people from trying?

I am interested to know what others think?

Thanks for that. Yes, I've tried quite a range of fasting variables, but not 3 days in a row since I was in my twenties and young and stupid!
Certainly different lengths of fast seem to suit different people. I have found 16/8 easy to do but I don't lose weight on it; 19/5 was harder and didn't seem to help much; 4/3 was interesting and better than anticipated but bunged me something rotten! 5/2, the good old classic standby, is fine but currently my lost weight returns by each next fast so not going forward just now.
I intend to continue fasting regularly after the middle of July for the health and anti-aging benefits, and just hope eventually some more unwanted weight does drop off.

Personally, I see nothing wrong with responsible adults doing prolonged/extended fasts but this has been discussed and agreed within this community to NOT be a topic of discussion here and I respect this. However, I would, privately, give the same advice to anyone asking me if they should try it as I do to people asking about IF in general, if it suits you and you are happy and healthy doing it, then do it.

Ballerina x

Used to do three or more days fasting/ starving over and over as a young person..don't think i' m capable of it any more,nor has it done me any good as healthwise I' m not great.
Personally not for me but good luck to anyone who is willing to do it! X

Also its a "study" with no scientific proof or backup.

Well I have no idea where it went, but we used to have a thing on here about extended fasting.

It is NOT ENCOURAGED on this forum and should ONLY be undertaken under a doctor's supervision. The max fasting that can be discussed or encouraged on this forum without someone being under a doctor's supervision is 36 hours.

I believe that two days back to back with calories consumption of 500 calories is allowed, but not encouraged.

There is a risk of "refeeding syndrome" which is why fasting for a longer period should only be done under a doctor's supervision. Refeeding syndrome can be dangerous and must be managed by a medical professional.

Hopefully Carorees will pop on with the missing information that I can't find

Longo's study was done with people being under medical supervision. Tracie is right that there is a risk of refeeding syndrome with prolonged fasting. This is a dangerous, potentially fatal, condition resulting from introducing carbohydrates after a long period of no or low calorie intake. It has been seen after as little as 5 days. This is why we have decided not to discuss or condone fasting for more than 3 days on 500 cals or 36 hours with no calories.

Since Krista Varady has allowed three days on 500 cals for people struggling to lose on ADF, I think that we can say 3 days is ok but I would not recommend longer for safety.

IGF1 has been shown to decrease on an ADF protocol and Dr M got reductions doing 5:2 I think there are plenty of safe fasting protocols we can do without needing to do long fasts.

You can also mess up your electrolytes with unsupervised sustained fasting or very low calorie eating. That can give you a heart attack.

angie090465 wrote: Also its a "study" with no scientific proof or backup.

I wonder what you mean by that? This study is published in a very good journal (which isn't proof in its own right, but does mean that the research has been peer reviewed by experts in the field to look for flaws in logic, methodology, etc.) and has plenty of scientific evidence in it. Do you mean that it's a single study and you would like to see others that come to similar conclusions?

p.s. i seem to recall that in Longo's studies, the subjects don't do zero calorie fasts but get 500 per day. Does anyone know whether this is the case in the study being discussed here? (I should just look it up but being lazy)

30 years ago, in Japan, I joined a Buddhist practitioner who was fasting for a long period -a week I think - as a protest about nuclear weapons. We were in the Nagasaki square. He would only allow me to fast for 3 days and he supervised me very closely when I broke my fast. I had to drink litres of water, eat umoboshi plums and rice and salad. It was all very Japanese. It did clean out my system and made me feel very Spiritual and amazing. That lasted for a few days. It isn't something I would want to do regularly, or even something I would be able to do without the passion of a cause - beyond losing weight.

The more I hear of what you've done the more intrigued I am!! Does that partly explain why you teach Japanese now?
I did the three day as recommended by Varadi, but it didn't really have any effect, and as others have reiterated we don't encourage it here.

Well I am completely in agreement with you all - I am not thinking of doing this for myself, but just to find more sensible responses to those who enquire about it. To my mind, the research that Valter Longo is doing is really pushing forward our understanding of the mechanisms that make intermittent fasting work to improve health, as we are seeing with so many people who are following 5:2. But his studies are done with mice and in the Lab, so whilst they are good solid science, they are not in any way a recommendation that this is something that should be followed by humans. In the very small trial that was conducted with cancer patients undergoing chemo, there was of course very close medical supervision. I have been unable to discover what protocol they were following with regard to calorie intake. But in case case, that was way back in 2009, so it is nothing new. I am going to stick with my advice to do no more than 2 days b2b. If you want to remove this post, then please do, no offence taken!

A 3 day fast with or without any calories is not something I would ever wish to undertake myself or encourage others to do it, I find one day more than enough but as a heathy, consenting adult I have no problem with any other healthy, consenting adult doing it. Dr M did 4 days with only 25 calories each day with no ill effects and whilst he was was being supervised there was never any suggestion of any medical intervention being even remotely considered. That said, if I was given the choice of bungee jumping or doing without food then I'm afraid that as dangerous pastimes go, being hungry would win every time

Ballerina x

P.S. Even though we are actually discussing this I am still in favour of it not generally being an acceptable topic here for all the reasons that were discussed originally.

Just wanted to add that, when we discussed our forum policy on extended fasting, we agreed that it is ok to discuss prolonged fasting in the lab section (as this thread is) in the context of discussing the science.

I suspect that many types of IF will reduce IGF1 because of the overall cut in carbs and protein created by fasting. It's just that there have not yet been many studies on it.

There is research (which is having positive results) in cancer patients using the ketogenic/modified Atkins. I would be interested in finding out more about that as opposed to prolonged fasting (which I wouldn't personally recommend to anyone!)
I can state that the keto diet wasn't great for weight loss as my daughter went from 12kg to 18kg in 6 months! But it was great for her epilepsy!