Interview: Fasting Mimicking Diets for Mast Cell Activation & Allergies

UPDATE: The USC Longevity Institute have kindly agreed to send me a fasting mimicking pack to test so that I can share my experience with you. I’m just waiting on medical approval and then will jump right in. 

Water fasting’s health benefits have always interested me. Recent research showing that fasting can prevent mast cell degranulation (the process that releases histamine into the blood stream from mast cells) in mice [1] and rats [2] were a great find, but sadly I eventually found that water fasting was too stressful for my nervous system.

And then, while perusing the diet and health section in a bookstore, I stumbled onto the research of Dr. Valter Longo, director of the USC Longevity Institute, regarding what he has dubbed the Fasting Mimicking Diet (FMD).

In a nutshell, the FMD is essentially one which recreates the anti-inflammatory, cardiac, cancer and neurodegenerative protective effects of water fasting in a less extreme way, by allowing the consumption of 750-1100 calories for a five day period.

There’s so much press coverage of the general benefits of the FMD that this interview with Dr. Longo focused on exactly how this fasting style benefits those of us with mast cell activation, histamine intolerance and food allergies.

The most exciting take away from my chat with Dr. Longo is that his new research on mice showed that a three day fast (which would correspond to a five day fast in humans) induced a 40% regeneration of immune cells (which include mast cells). He believes that the cells that die off are “faulty” and that the newly minted cells could offer some kind of resolution/positive benefits to immune system conditions, including mast cell activation, histamine intolerance and food allergies.

This corresponds to something I’ve heard mast cells doctors tell folks: avoid your triggers to stop activating mast cells for long enough and they’ll die off eventually. Well, this seems like an incredible shortcut that doesn’t involve massive deprivation.

As an aside, I recently visited with a friend in Portland who has mastocytosis who commented that I eat few meals and don’t snack. Yes, and that’s partially how my symptoms cleared up: having a liquid in the morning and then two meals is a kind of mini fast, causing less inflammation to be released by the digestive process. Not as great as a five day fasting mimicking fast, but still better than constantly stuffing my face through the day as I used to. 

Other super interesting take aways from this interview:

– The amount of protein you’re likely eating is prematurely ageing your cells

– Why a mostly plant based diet is best for longevity and immune system function

– The FMD may soon be approved for immune system dysfunction and cancer treatment

– How to get started on this fast

– The effect of fasting on the adrenals

You’ll find recipes full of foods with antihistamine and anti-inflammatory properties my books Anti-Recipes and The Anti-Cookbook


The podcast interview with Dr. Longo is just below and you’ll find the transcript of our chat under that.


Yasmina: Joining me today is Dr. Valter Longo, whose pioneering research on Fasting Mimicking Diets has been excitedly trumpeted across every major news outlet from the United States to Japan. Dr. Longo has been researching fasting since joining the Laboratory of Calorie Restriction pioneer Roy Walford at UCLA where he studied the effects of fasting and the ageing of the immune system. Now the director of the University of Southern California Longevity Institute, Longo has spearheaded some of the most exciting new research on FMDs, Fasting Mimicking Diets, which allow 725 to 1100 calories daily while still offering the neuro and cardiac protective ageing and anti-inflammatory benefits of water fasting with less stress to the system. Longo’s FMD allows you to consume just enough calories to keep the body running, making it much easier to stick to. I mean, I don’t know about you, but water fasting is really only practical if you are shut up in a Buddhist monastery or sitting in a Zen Garden counting the rocks for the duration. Dr. Longo, thanks so much for joining me here today. I have been reading your research on Fasting Mimicking diets with really, really, great interest. It is something that those in the histamine intolerance and mast cell community speak about a great deal given that food is such a strong symptom trigger for many of us. The skipping meals thing becomes a way of life because cutting the caloric intake seems to have a positive effect on the health, at least in the short term, until we run low on nutrients. At least that has been my experience. So, I have done many water fasts in my life, believing that I am doing something good for my body. While I know that water fasting is beneficial for some, at least in my case, it turned out to be far too stressful for my body. Dr. Longo, please give us an idea of what the Fasting Mimicking Diet is, and how you think, what you think, the medical applications of this will be.

Dr. Longo: Yeah, it’s right up in high in calories, you have between 750 and 1100 calories a day, are high nourishment, and they’re really like a medicine. They are all plant based. So there’s no drugs in it. But they’re really like a medicine. And we really foresee that very soon, I mean we’re talking to the FDA very soon, and we think that people are going to go to the doctor, and the doctor already saw the patient and is going to say, “Oh, you know, you have this condition I am just going to put you on three cycles of this and we’re going to monitor, in your case, the histamines and the other immune cells that are implicated in the disease, and that’s it. Together, with immunology, with the doctor, they can come up with a plan to see if this works. Of course, it comes with instructions of all these things, the exclusion criteria, all the things we use in clinical trials are going to apply. Now, we didn’t want to wait until the FDA approval because that is going to take another six or seven years. But because it’s food, once we finish the trial on seventy to eighty people, which is pretty much done, then I think that with the supervision of the doctor, these Fasting Mimicking Diets can be recommended to the patients and they are not there to treat or prevent diseases until they are FDA approved for that purpose. Now certainly the doctor can decide what diet they put their patients on and if they decide that this is the diet that they want to recommend then that is in their call.

Yasmina: So, I would love it if you would please share with my readers your finding on FMD’s, specifically their effect on the immune system and mast cells.

Dr. Longo: We actually published another paper about a year ago more specifically looking at the immune system, although this paper that we just published also did so. And in that paper, we showed that mice undergo a long period of fasting, three days which is about, we believe, the equivalent to five days for humans, we showed that first a decrease in the number of white blood cells and then following the receding an increase in this white blood cell number. And this was caused by stem cell based regenerations. So, in other words, about forty percent of the of the mouse white blood cells were destroyed during the fasting, and then upon the receding they will rebuild a regenerated to show that the mice ended up with a new set of cells, basically. So, obviously now we followed up with this study with the Fasting Mimicking Diet, basically showing that it is effective also in old mice in rejuvenating the immune system of old mice. And we believe that is, of course, by a similar mechanism, which is determined on homopathetic stem cells. And so the good news, I think, for any disorder of the immune system, and I can’t really discussed it very much, because we haven’t published the other paper, but we certainly are working multiple disorders, several autoimmunity based disorders, and I think the good news is that is by getting rid of the the old cells or damaged cells, and generating new ones, of course, you have something that tends to eliminate the problems, and possibly the problems that you are interested in.

Yasmina: Something that news reports on your findings really honed in on is that the benefits of the FMDs last for some time, even if the subjects went back to their previous eating habits, which, in some cases, wasn’t very healthy at all. Can we really go on this fast once a month and then go back on a standard American diet? And I also wondered if you believed that if people choose, instead, to adopt a healthier diet, will there be a better chance of rebuilding healthy immune cells?

Dr. Longo: Yeah, so, you know obviously we were very interested in that and my, one of the gurus of restriction was my mentor Roy Walford a long time ago at UCLA, and I always. I never went in his direction which was chronic calorie restriction and the reason was that I thought nobody was going to do it, A, and B I also felt that there was going to be side effects and by pushing a system to the limits all the time, you’re going to get benefits but also side effects. Now Walford was a great guy and his research on calorie restriction was of tremendous help of to understand basic mechanisms but had those problems. With that said, then obviously we think that A) there is an ideal diet but B) there is a reality, and the reality is that a lot of people are not going to do an ideal diet, in fact the great majority of Americans probably will never do that. And so we now know because the mice for example were on an 18% protein diet, relatively unhealthy diet and we just switch them twice a month to four days to the new diet and starting middle age and this worked extremely well; both with the regeneration of the immune system with lifespan extension with reduction in inflammatory diseases, etc, etc. Now in humans we started with the first 19 patients and the controls and we see the same, certainly all the same, changes in these people, also are not asked to make any changes. Basically they’re just asked to return to whatever it is they did before and just do this for five days once a month. They got a box containing all the food and they used that and then they went back to normal. So, then we know that it works with that change. It doesn’t mean it wouldn’t work better if you did switch to a diet that is also ideal in between.

Yasmina: Given all your work with the immune system, what do you consider to be the ideal diet?

Dr. Longo: The ideal diet is a plant and fish based diet that is low in protein, about 0.37 grams per kilogram body weight and that may increase a little bit in proteins after age 65 or 70, depending on the need, and then a diet that is high in nourishment meaning a lot of greens a lot of vegetables, not so much fruit, a little bit but not very much and a diet that is rich in nuts, rich in olive oil, legumes rich also. I guess that some people might have allergies to it, a lot of the times these allergies are just temporary ones if you’re used to having a bad diet and you switch to legumes you might have some issues but in a lot of people those tend to go away. That doesn’t mean they’ll go away in all people, so for some people they’re just going to have to find the food that they’re okay with, but I will say the great majority of people can be on this diet and can be very happy. Let’s not forget that some of the populations from around the world whether its Loma Linda in California or Okinawa or Southern Italy or Greece, they’re pretty much on this diet, different versions of it, Okinawan’s eat sweet potatoes and Southern Italians eat green beans and the Californians probably eat other type of greens but overall they have very similar diets and not surprising they’re among the longest lived in the world.

Yasmina: Could you please give us a breakdown of the macro nutrient ratio of the Fasting Mimicking Diets used in your studies?

Dr. Longo: We don’t like to talk about that because when we do that everybody…we did that…we made the mistake seven years ago when we were doing this for cancer and the result was, which is very very scary, everybody went home and tried to do medicine at home. And then we started hearing back the problems, a nurse didn’t do it the correct way and got liver damage out of it, another person that passed out and hit the shower and was rushed to the hospital. Another one that passed out in the shower too. And this is a very powerful but it also it can greatly benefit you if you do it correctly but it can also hurt you if you don’t. I know that people think it’s food, how can it hurt you, but it can hurt you. I think very soon we’re going to have this available in a package from a company called L-Nutra that makes it, I don’t make any money out of it, so people can relax and not worry that I’m doing this to make money cause i donate everything. But I think it’s very important that it’s standardised and that’s what we’ve done.

Yasmina: As I mentioned earlier, water fasting turned out to just be way too stressful for my body and studies show that stress is a mast cell and histamine trigger. Are there people who are just not suited to FMDs? Has stress been an issue in any of your studies on fasting?

Dr. Longo: Well, I’ve done it both ways and so has my lab and my parents and my brother, my sister, and yeah water only fast, i’ve only done it one time and i’ll never do it again. It was just psychologically torture I was just [inaudible] the biggest one in the world for fasting and you know we always joke around but they. I told them, most people are going to think of this as torture. But I’ve done the Fasting Mimicking Diet and it’s just a completely different thing. Now you can eat three times a day and you can have snacks and you can have bars and you have soups and etc etc, so it really. I, as well as 95% of the patients in the trial, only 5% dropped out, and I, as well as them, felt that it was actually very easy and actually you may want to send your readers to the BBC site because we had Peter Bowes the journalist of BBC in the trial so he wrote a 3-part story of his experience in the trial and yeah so then people can read that and it’s an interesting story that he wrote.

Yasmina: There’s a lot of talk in the blogosphere and most Facebook groups about fasting causing stress to the adrenal glands. Have you seen any evidence of that?

Dr. Longo: Well, this is one of the reasons why we spend a lot of time doing clinical trials and also collecting data from the big clinics so now we’re trying to get safety data from the Buchinger clinic. They fast about 5000 people a year and, as far as I know, I’ve seen really no evidence of adrenal damage. That does not mean there are clinics are for profit, so that doesn’t mean that we know yet. There haven’t been clinical trials done. So, those need to be done but certainly in our trials of 80 people we did not see any issues with the three cycles of the Fasting Mimicking Diet. Now, of course, water only fasting and fasting mimicking are completely different things. And I suspect that many more side effects are going to be seen with improvisation. For example, gall stones, very well established, there are papers on that, particularly if you have a high protein fasting diet, so that if you include proteins in the diet and you otherwise fast but also the water only fast possibly could contribute to gall stones, particularly in women over 40 and who are obese. So yeah, there’s probably all kinds of problems, they’re going to be rare, particularly with the Fasting Mimicking Diet but we need to do more studies and this is why the FDA process is important, because, you know, when we do the thousand people trials these things all come up and then eventually you need a phase four when you monitor thousands of people. And those things should definitely come up if they’re real. I doubt there’s going to be any adrenal issues with the Fasting Mimicking Diet, but we need to keep studying it and make sure there’s none.

Yasmina: Indeed, I’ve read some incredible water fasting horror stories. I’ve always found it strange that people at home would, on their own, while at their weakest and probably most starved of nutrients would embark on a water fast. I mean, it has it’s benefits of course, but going it alone with no medical supervision is probably unwise for many. But is there anything interesting you’ve come across with regards to histamine or IGE allergies as relates to fasting?

Dr. Longo: We know that during fasting there is a release of cortical steroids, and the good news is it’s all timed and it’s all done in a natural way so it’s a level of cortisone basically that is able to shut down a lot of the immune responses that are not needed but then it goes away. So although we haven’t looked at allergies yet, we suspect that this is probably going to have a strong effect in allergies that are chronic allergies and conditions where you have an immune system that is misguided.

Yasmina: I’ve seen that USC has developed a kind of package diet that includes all of the foods that you would need on an FMD properly calibrated with the macro nutrients and everything. When will this be available for sale?

Dr. Longo: It’s ready to go, it’s just a matter of launching it. I think in the next three months it should be available. People can keep checking with L-Nutra, the company, and they can send emails to ask when it’s ready. Eventually, we hope to train people at USC through a certificate program and still have people that are much more familiar with it because they understand. I’ve been doing this for ten years telling people, “Go find a doctor,” and they come back to me two days later and say, “There is no doctor like you.” And so I think that doctors are starting to see more integrated medicine. So I think people can just go to an integrated medicine centre in their city and say, “I want to do this, I really decided on this, I know this is clinically tested in a top university and I just want to do it.” And I think it shouldn’t be that hard to find an integrated medicine doctor that is willing to follow the patient while they’re doing this. So you just go there and tell them…or they can contact us and we can get in touch with the doctor or conduct a Nutra (?) and then they can set up all the paperwork needed to do it.

Yasmina: That’s wonderful. Thank you so much for joining me for this interview today Dr. Valter Longo, Director of the USC Longevity Institute, talking about his pioneering work on Fasting Mimicking Diets and the AlNutra System.

Dr. Longo: You’re very welcome.

Yasmina: Now please, everyone, before you go out and try and do this yourself at home, please know that the calorie macro nutrients need to be in a certain ratio and messing that up can lead to gall stones, fainting, or more serious health issues. To me, the main benefit of the FMD is being able to lead a somewhat normal life while fasting. Dr. Longo believes that light exercise is possible while on FMD. I’m personally really looking forward to getting on one of those fasts the moment that Doctor’s are trained up and I’m definitely going to check out the products once they’re released, and begin the “Doctor Hunt.” That’s going to be interesting. Don’t worry, I’ll be updating you all as soon as that happens and I’ll report back on the results immediately. You’ll find my favorite non-fasting liquid recipes in the Anti-Detox book at my website, the These are my go to recipes when feeling like I need to hit the reset button. You’ll also find super-duper high nutrient anti-histamine anti-inflamatory ingredient rich recipes in the Anti-cookbook and Manfood for those with healthy appetites also on my website. And you can download my free e-booklet on how I reintroduced foods from the freebies page on my website. Just look for it in the main navigation on my homepage. Thank you so much for joining me here today, I’m Yasmina Ykelenstam; the Low Histamine Chef.

Thanks for listening to the Low Histamine Chef Podcast. Don’t forget to sign up for Yasmina’s mailing list over the to get your free copy of the 32 page food re-introduction e-booklet. Until next time, thanks for listening.

You’ll find recipes full of foods with antihistamine and anti-inflammatory properties my books Anti-Recipes and The Anti-Cookbook


Please remember, even antihistamine and anti-inflammatory foods can hurt us, please always exercise caution and consult a medical practitioner before adding new foods. 





Check out these other Healing Histamine blog posts


Yasmina was an award-winning broadcast journalist with a decade of experience covering war zones for CNN and the BBC. She devoted her journalism skills to researching and writing about histamine. Click here to learn about her. Each post is carefully and fully referenced with the latest scientific research. Not sure where to start? Here’s a four week meal plan and overall Histamine Reset.

4 Week Histamine Reset

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