How do fasting day food choices affect IGF-1 reduction

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How do fasting day food choices affect IGF-1 reduction

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  • I’ve been doing 6:1 fasting for four months now.
    I chose 6:1 to avoid losing weight.
    I had blood tests on my first ever fasting day and had IGF-1 of 103ug/L (13.36 nmol/L). The lab results suggested the suitable range was 75 to 263ug/L.
    For 4 months I have fasted every Monday, by eating 40 grams of raw almonds and a raw tomato for lunch (<300kcal) at 1:30PM, and then 70 grams of porridge oats boiled in water (also less than 300kcal) for dinner, straight after burning about 230kcal on the Exercycle.

    My IGF-1 level is now slightly HIGHER, at 106ug/L.

    I am wondering if my choice of food when fasting is affecting my IGF-1 levels, and how I should change my routine to achieve a lowering of IGF-1, since my understanding is that many of the health benefits from this diet that do not come from achieving a healthy body weight, come from lowering IGF-1 levels, or at least are accompanied by lower levels of IGF-1.

    Hi, it is probably not your fasting day diet that increases IGF-1 but your overall protein intake through the week as a whole.

    Keep protein intake to 0.8g per KG bodyweight and it should drop.

    Thanks for responding Jono, but your answer leaves me perplexed.

    If, as I understand it, most of the non weight-loss benefits of fasting come from lowering IGF-1 levels, and IGF-1 levels are mostly controlled by overall protein intake over the week, then WHY am I going hungry every Monday?

    Would I be better off just moderating my protein intake and eating 7 days a week?

    Difficult to answer that one, the body is a very complex organ which is not yet fully understood and I am not a doctor, just an educated layman. However, it does appear that lowering protein intake to recommended levels does lower IGF-1 in humans. (In animals/mammals) calorie restriction does the same but for humans it appears are tied to protein intake also to reduce levels.

    See this from Dr Luigi Fontana.

    Obviously you can lower IGF-1 this way alone, however, I see many, many more benefits from fasting at the same time. And remember that whilst fasting you are not ingesting protein!

    I fast daily now for between 16-20 hours leaving me a 8 to 4 hour eating window, dependant on how I feel that day, during this eating window I eat 2 meals. I find it easier to manage protein intake this way as I can easily track how much I ingest in just 2 meals. The meals have to be good ones though, balanced as these are your only opportunity to get your calories/vitamins/minerals etc.

    I think overall it is better to fast (whichever method of fasting you choose) AND control protein intake and I am certainly feeling good on it and my weight is stable now. I came down from 80 KGs and now am around 66-67 KGs, and more muscular to boot.

    I think at the end of the day, the documentary was great, the book is great but each of us really just has to find our own way as we all have different needs and available resources/time. There is some great info out there and some rubbish, try looking at Brad Pillons site, Eat, Stop, Eat his site is full of great information. Also the IfLife talks about different fasting methods.

    Hope this helps you and good luck on your journey as that really is what we do. I do not ever see myself not fasting but how I do it may change over time as we find out more about the body and its workings.

    Thank you once again Jono, for taking the time to answer. From reading about studies relating to the work by Dr Fontana and others, it appears that lowering IGF-1 levels is indeed a very worthwhile cause, AND that the TYPE of protein may be as relevant as the amount of protein, in influencing the IGF-1 levels in us humans.

    Animal protein, and animal-like protein (soy) would appear to help maintain unnecessarily high levels of IGF-1, whilst the recommended levels of plant based proteins would generally appear to help lower it.

    I never thought I would ever consider a vegan diet, but with some family history of early death by cancer I’m motivated to try it, plus the 6:1 fasting, for 3 months to see how it affects blood test results.

    Hey NZRusty, I can see that you take this subject very seriously indeed and apparently with good reason and it is a pleasure to be able pass on any small knowledge I might have gained to help you achieve your goals, especially given your name sounds like I could get a free holiday in New Zealand as a result!

    I had started to read a little of the differences in animal and plant proteins but not gone very far down that route……. it appears that I may need to do so soon. I had not previously considered vegetarian/vegan as I like a bacon sandwich too much ;o)

    For me this site (and sites like it) are a God send, every person on here is on a journey to an almost completely different lifestyle and to think that only 12 months ago not many of those journeys had even been started. I put above that I was ‘just an educated layman’, now I think not true, I am just a layman, still lots more to learn.

    I wish you sincere good luck on your journey and I do hope that it is a long one in lifespan. You appear to be looking in all the right directions given available knowledge today.

    A friend of mine a few weeks back commented that we may be one of the last generations that actually has to die, not sure I want that (would be a nightmare for my grand-children having to put up with and support me) but a longer health-span rather than life-span, I could go for that. Fasting and protein (animal or vegetable) restriction it is for me I think until I learn otherwise. Oh…… and obviously lots of exercise ;o)

    Good Luck

    Hi again Jono. Definitely from New Zealand, and it sure is a place worth visiting 🙂
    I reckon you should stick with the ‘educated’ tag unless you can show me an educated expert who actually knows everything in their area of “expertise”.
    Seems there’s plenty of resources on the net informing on adequate nutrition without animal products in one’s diet, so now I will try it for a few months and report back with blood test results, and any noticeable health related changes (except for getting older).
    Your friend may be right that we are “one of the last” generations that actually has to die, but it seems to me that it would ne more helpful to be “one of the first” that doesn’t !
    Best regards and good luck with your own journey.

    Hey NZRusty. If it’s IGF-1 levels you want to control via fasting then another thing to consider (alongside the protein limitations already mentioned) is 5:2 rather than 6:1. From what I’ve read you don’t really get much of an effect on IGF-1 from only 6:1 as your body isn’t in a fasting state often enough/long enough. This isn’t to say that you don’t get many of the other benefits of IF whilst on 6:1 but if it’s specifically IGF-1 levels you’re concerned about then 5:2 seems to be the way to go… Good luck!

    I can’t put my hands on the article I saw about this right now (I’m pretty sure it was mentioned in Michael’s documentary too) but it has always been my understanding that the IGF-1 benefits only kick in on the 5:2 diet if you actually fast (proper fast with nothing but water/other no-calorie fluids) for more than a certain length of time. I’ve read 14 hours and 16 hours as the magic numbers – so I always assume the worst case scenareo and go for 16 at a minimum.

    Unfortunately IGF-1 testing is not something that the NHS would be overjoyed to provide for no particular reason, so I’ve no idea how mine has been affected by the diet. Maybe those who are getting tested could let us know if the longer ‘genuine fasting’ period has the desired effect.

    I agree with your comments TracyJ that the benefits of IGF-1 only kick in at 5:2, it might be possible to maintain them at a low level on a 6:1 but only after they’ve already reached that level.

    I’m reading “Fasting and Eating for Health” by Joel Fuhrman MD, it was first published in 1995 and most of the references are no longer available so it is not possible for me to examine the detail. He doesn’t specifically mention IGF-1 but he does talk about “Repair Mode” and says that it happens best after three days of total fasting, the maximum that he recommends without medical supervision. He does have another book published earlier this year but the first edition seems to have sold out, I was advised by the bookseller only yesterday that it is now in stock and a copy is on its way to me, hopefully the new edition will consider the latest research and have some useful references.

    In reading your comments, Jono, you appear very knowledgeable and also noted Fontana’s comments re: protein intake. I’ve been limiting carbs, which has been easy (and I’m on a 5:2 plan), but trying to also now limit protein is proving very difficult. Is anyone else doing this and, if so, any thoughts or suggestions? I was surprised how much protein I’d been eating.

    Otherwise, I was curious as to your thoughts on “limits” – i.e., given I’m on a weight loss program, do you think I should figure the 0.8g/kg of protein for my goal weight or for my current weight? I haven’t found anything online about this (other than one somewhat questionable source saying average the two…which seems sort of a cop out). My thinking has been that I should calculate for my ideal weight and stick to it. I do love my fast days for it’s at least twice a week that I don’t have to fight my protein limit (note that Fontana also suggested coming in a bit under 0.8g/kg…like 0.73g/kg to lower IGF-1).

    As for protein type, I believe Fontana also said that vegans had to keep their protein levels low as well…that, even though plant protein may not be as bio-available as animal protein, high levels will still spike IGF-1. Last but not least, dairy is apparently the worst as it’s specifically designed to promote growth (i.e., IGF-1). Not sure if I can give up cheese or cream in my tea quite yet. 🙁

    Hey NZRusty. How did you go about obtaining your IGF-1 reading? Did you go through your GP ( I am in NZ )
    Thanks if able to respond.

    Hi Rochelle

    For myself personally I would go to the lower end of the scale. Also note you can eat as much salad/vegetables as you want, so no real need to go hungry, apart from the fasting part that is ;o)

    When not fasting the only thing I restrict is protein, all other foods I love in abundance. Nowadays for me a ‘meat and 2 veg’ meal is more like a ‘bit of meat and 4 veg’ meal. I still have loads of energy, if not more and almost never get hungry when not fasting.

    Good luck and hope this helps. Sometimes it is best to look away from the weight-loss targets for a while and just enjoy the healthier foodstuffs when eating, for me the weight just dropped off almost without thinking about it.

    Like the name by the way, I live near La Rochelle in France!

    Hi there Elliott and NZ Rusty, Good to see we Kiwis are looking after our health.

    Am interested in the IGF – 1 test as well. Whenever I ask my GP for any of these blood tests, I am fobbed off. I wanted to find out if I was insulin resistant as opposed to the fasting glucose test. Not a goer apparently. So how did you get the protein test NZRusty.

    Jono, you should come and visit our great little country. We have a bit of an infinity with the French but assume you are not a native?

    Hi Jono,
    I lived in France for 13 years and still run a business there near’re not so far away. BTW: I am now on Coconut and Almond milk as I hate soya or rice milk, but I can’t find it locally in France.
    I have been 5:2 ing since the documentary. It was my husband who first saw it and started doing the diet to lower IGF1 levels. I joined in straight away but have to confess that it was the weight loss as much as the IGF1 that attracted me.
    The weight loss was wonderful as I have only had three quarters of a stone to lose and I just couldn’t do it any other way and keep it off. Great..but I really do want to lower IGF1 as well.
    Husband , who is a dentist and therefore a bit scientific( also plays rock and roll and is not at all dentist like) has always maintained that it is the lowering of protein intake that lowers the IGF1. It seems from NZRusty’s experience ( and others) that fasting alone won’t do it.
    I AM CONFUSED. Does fasting contribute AT ALL to lowering IGF1?? I understand the benefits of not being overweight, and the diet certainly helps with that.
    But the major push of the doc was about the fasting state, putting your body into repair mode. There was mention of lowering protein intake but it was fleeting and unclear. Dr M tried all forms of fasting until he settled on the 5:2 as a sustainable way of keeping various not so good markers, and IGF1, down. He has bacon and eggs for breakfast on fast days and didn’t put any emphasis on controlling the protein levels.
    Is it as simple as ..if you don’t stick to the RDA of protein for life then your IGF1 levels will stay where they are now?
    And if so…as several people have asked, why are we fasting apart from our weight??? HELP !

    Hi Sarowland,
    This thread seems to have become a bit stagnant but I spotted your comment about why are we fasting if it is not about weight.

    For me it is about the repair mode factor. In particular the drop in insulin resistance and the rather tenuous evidence ( in mice) that the brain grows new neurons during the fasting period. My interest is due to hereditary diabetes in my family and my husband’s development of early onset dementia. Neither of which I am interested in acquiring!! Heaven knows if it will work.

    I have only 3 more kgs to lose really so the weight is not too much of an issue. Changing my eating is though. I have terrible bursts of comfort eating and when I look back over my diaries, that has been the case for years. I hope the damage I have done is reversible.

    It would be great if Michael was able to shed more light on this, wouldn’t it?

    It really would !All the other benefits are great, but the IGF1 thing is still unclear to me. Is it just protein restriction or does 5:2 help as well?
    I had my father in law living with me through his last 2 years of cancer and dementia, and I’m with you on anything that could help prevent either or both !

    As for mad comfort eating.. I really empathise as I am the same. Actually I was much more controlled on the Slimmer’s World diet and have gone a bit bonkers on 5:2.The temptation to binge is overwhelming because you can tell yourself you can fast it off.
    However SW was a 7 day a week undertaking. At least on 5:2 there is more enjoyment! And my weight has stayed off even if I have had to so the odd extra fast
    Only 3kg to go…well done. That’s the hardest to lose and what 5:2 can achieve for you I have found. I notice you don’t get much sympathy if you only have half a stone to lose, but as I say, I am really pleased as I have never been able to get that last bit off at 57 years old, until now. Keep going and you will succeed even with a bit of mad eating !

    Hi Saroland

    The way I have read it is thus. Eat less protein and lower IGF-1, stay to RDA levels and you ‘could’ lower IGF-1 by up to 25%. This is not the end of the story though.

    Lowering IGF-1 in itself does not put the body in repair mode per se as it is still processing other food types and as such is still in an active state. It is only the fasting that appears to put the body in repair mode.

    Further reductions in IGF-1 whilst fasting as because you are having NO protein during a fast. (Or I do not anyway, to me a fast is a fast of up to 24 hours with no calories at all). The beneficial effects of complete fasting decrease on a sliding scale after 24-28 hours it appears so longer fasts would be less beneficial anyway, at least on that sliding scale. Longer the fast, lower the effects over time.

    Fasting up to 16-24 hours means 2 things to me.
    1. No protein is being ingested and thus no IGF-1 spikes at all, hence a drop over time of up to 50% in IGF-1 as seen on the documentary both on prolonged fast and 5:2.
    2. Body goes into repair mode as food stores run out, around 12-16 hours-ish. This fasting is what kicks off repair mode.

    Whilst the 2 are linked at seems to me they are separate, one gets lower IGF-1 and the other gets even lower IGF-1 and sends the body into repair mode.

    The whole point of the fast diet for me is ‘the fasting’. Appears to be the only way to get all the benefits and it certainly adds to the lower IGF-1 in protein restriction by lowering it even more.

    Now, fast properly AND stick to daily protein RDA and you should become super-human ;o)

    Hope this helps.

    Hi Elliot and Lizy. Sorry for the slow reply but life’s been rather hectic.
    To get the IGF-1 tests, I just asked my GP. She advised I would have to pay and then added it to the blood test slip of paper.

    I just got mine tested again after 3 months of being vegan and trying (not too fastidiously) to limit my overall protein to about 0.8 grams per kilo. I’ll post the results when they come back.

    I note some people are suggesting that 5:2 is required to have much impact on IGF-1 levels. I’m struggling to maintain my weight on 6:1, so I think 5:2 would be a bad idea. I eat the same on every fast day: 40 raw almonds at 1:30pm (over 18 hours since last meal) and 72 grams of oats cooked in water at about 6pm.

    More to follow when my test results come back ….

    Hi Sarowland, thanks for the reply. Our body image and the way we feel about it seems to be so tied up with our childhoods and our emotional intelligence. Something that is a constant battle to acquire and maintain. As I sit here and reply to you I have this conversation going on in my head about whether this way of eating is going to be of benefit long term or is it yet another fad that I have bought into. Jono, seems to have that under control and I admire his (?) self discipline.

    However having gotten into my 60s without taking medication or being too overweight, I should be counting my lucky stars rather than bemoaning my less than enthusiastic will power. If nothing else these forums have introduced me to a lot of inspiring people and some very interesting science.

    Good luck with the protein. I have been trying to follow Jono’s suggestion. Not too difficult if I am behaving myself:D

    Hi Elliot and Lizy
    im also in NZ and just had my IGF-1 tested. You dont need to do it via a GP you can also do a self referral at a labtest collection centre. Details are here

    The above article might be of interest re the reduction of IGF-1.

    Thanks so much nzbaldey. I live in Hamilton so not too far to go to get the test. I will ask my GP as well just in case she is feeling inclined.

    Hi Lizy and Jono. Thank you Jono…I know you are right, it’s just hard sticking to the RDA protein ! Just to throw you a curve though, I tweeted Dr M about the protein thing ,who (rather thrillingly) replied. Being a tweet it was v short , but he said yes..stick to the RDA, and he also said it’s important to have some protein (about 18 gr) on a fast day. But I still don’t know if he stuck to the RDA daily for those initial 6 weeks he was doing 5:2, after which he got a huge drop in IGF1. My husband thinks I am being obsessive, but I just would appreciate some feedback from him on the details including how much plant protein is too much. As there is protein in most things, you’re up to 45 gr in a flash even if you are eating only vegan foods. I am sorry to be such a neurotic bore Jono !!!
    Lizy. I really don’t think it’s a fad because protein or no protein there are so many health benefits to fasting as we get older. And it really has enabled me to attain and maintain a weight I thought I was past being able to revisit and it’s a wonderful feeling! Just keep telling yourself that 2 separate days a week of exercising that elusive willpower ( and I have pitifully little myself) means 5 days of relative normality rather than us obsessing 7 days a week about what we are eating. I was a fat child and it does stay with you but getting the weight off is such a boost and so much easier on 5:2 I find even if it’s only 3kg. The feel good factor is bigger than you think! Lots of luck…keep posting..

    Hi Sarowland,

    I take your point with your ‘curve ball’, however, like I said, a fast for me is 24 hours max nowadays. So if I fast from 6PM one day to 6PM the next or 6PM to 1PM the next I still eat everyday and I have protein with each meal, just not as much as I used to do. And remember not all plant protein is complete protein, so unless you eat 2/3 plant groups that combine into a complete protein the effect is not the same. You need all 9 essential amino acids in the correct quantities to make a complete protein.

    On a 16-20 hour fasting day I will eat 2 meals one around or after lunchtime and one in the early evening and on a ‘full’ 24 hour fast day I will eat one meal in the early evening, but each meal will have some complete protein in it, just I find it easier to track intake on one or two meals a day.

    I think this is the real beauty of intermittent fasting, do what feels good for you. For me every day is a fast day, it is just a matter of how long and one meal or two. I try to throw in a 24 hour fast once a week but when fasting every day it is not like going 6:1.

    I run, cycle, do various strength related bodyweight exercises/routines, play football with friends etc. all with lots of energy and usually in a fasted state. I remember as an experiment I went 48 hours without food not long after starting 5:2 and felt absolutely great, felt completely empty and light but with loads of energy, but I then realised after much reading that I did not need to do that all the time to achieve my aims.

    For me personally daily fasting seems to be the way, but we are all different and obviously work, lifestyle and family commitments can dictate what is best for each of us. I did not want to unduly influence my 10 year old son so missing breakfast and/or lunch especially when he is at school was easier and I almost fell into daily fasting, I always had an evening meal with him. Now he just understands that his Dad does not need to eat all the time but he does as he is still growing.

    My best advise is don’t worry about it all, just do it your way. You will find YOUR way, you will also make mistakes, eat the wrong things etc. I still do, but I do not mind, but that is how we learn. I had a great full English breakfast with friends last weekend, first breakfast I had eaten in any form in about 7 months and I loved it, wrote the day off as non fast and got on with it again the next day, no problem, no regrets.

    I wish you luck, just go for it, you will find your way.

    Thank you Jono…I am still doing 2 fast days a week so I just have to get better at the( especially animal) protein reduction part.
    Your comment about eating 2/3 plant groups that combine into a complete protein was very interesting. Do you have any pet web sites with more info about that?
    Wish my exercise commitment was as good as yours!

    Hey Sarowland

    Most foods contain most of not all of the 20 amino acids, but they vary in quantities of each. It is 8-9 which cannot be synthesised within the body that are ‘essential’ and a food that contains each of these in the right amounts is considered a ‘complete protein’.

    Most plant food contain loads of aminos and a surprising amount of plants and unrefined foodstuffs are or are equivalent to complete proteins, that is they either do or very nearly do contain enough of each.

    I do not have pet web sites on foods as such, I am fortunate my wife is a great cook and I eat a very varied diet. So tend to get all I need from that. The other side of that coin is I have a 10 year old son, so burgers/chips/pizza etc. can also feature on the menu ;o)

    Best is to Google Protein in Plants and go from there. Or and follow the reference links for a starting point.

    You will be very surprised how much will power you have once you have your own defined path to follow. But do not get hung up on protein, your body will tell you when you need more/less of something.

    I have learnt 2 very important lessons in the last year since first seeing the fast diet documentary.

    1. You do not need to eat nearly as much nor as often as you think you do. Especially with a varied diet.

    2. Regarding muscle tissue as we get older…… Use it or lose it. It really is as simple as that. You can run marathons into your 80s or 90s but only if you keep the tissue active so it is not lost over time. And this process starts in you late 20’s early 30’s so it is never too soon.

    See, your journey to YOUR way is starting already ;o)

    Hey Lizy,

    I am also based in the Waikato (Cambridge) my gp is useless and wouldn’t get it done for me. Today I was in Hamilton and dropped into angelsea clinics path lab. I asked them and they were very accommodating – without a gp referral it cost $55 which I was happy to pay.

    Can’t wait to receive the results 🙂

    Hi t, thanks so much for that info. Christmas has sort of gotten in the way. Right at this moment am sitting at Matarangi on this lovely sunny day and contemplating a boogie. Fasting has not been a priority but have done heaps of beach walking. Happy new year.

    Hi All,

    Here’s a recap of my experience with IGF-1 levels.

    Before start of 6:1 fasting, 103 ug/L (recommended range 75-263)

    After 4 months of 6:1 with no other diet changes, 106 ug/L

    After 4 months of 6:1 with no animal protein or soy protein, and an attempt to limit overall protein input to the RDA of 0.8 grams per kilo of body weight. A substantial drop to 63 ug/L.

    I made no other deliberate lifestyle changes, although my diet now includes more nuts and seeds than before (eaten every day)

    Tres Bien NZRusty,

    To say the least very encouraging results. I read your expanded version in another thread and it appears you could well be right about animal/vegetable protein.

    Well done and I wish you continued success on your journey.

    I am currently investigating standing/sitting/exercising, scary stuff. See for an example

    It seems the more time we sit/are inactive the more we die (quite literally). It appears to me also that exercise and activity are also very closely related to diet/fasting. A lack of one can undo the other and indeed they compliment each other. After only 30 minutes of sitting down we can be in a degenerating state and longer hours of daily sitting is not reversible by 20-30 minutes of jogging either.

    Only way is to ensure you move every 20-30 minutes for about 2 minutes or spend more time stood up/moving. This was a real eye opener to me and has prompted me to buy a stand for my laptop so I can work stoop up/moving.

    Good luck

    Hi, reading this thread with interest. I’m also 57 and was not especially overweight to begin with (BMI hovering at 25-26 for past 10 years, 26 when I started 5:2 in November)but it’s come down to 24 now and I’m aiming to get to around 20 so that I don’t have to worry about getting back into that overweight range. I really don’t want to go into older age carying excess weight and developing all the usuals that go with it (high cholesterol, diabetes, joint problems, etc). I work with a group of people who are middle aged and often overweight and I see at firsthand that many of them have problems just moving around (heavy breathing while walking!)
    On the subject of protein, I’ve been a non-meat eater most of my adult life – after 8 years as a pure vegetarian I began to eat fish when a naturopath advised me to get more protein. Eating fish improved my health a lot. But as a non-carnivore, I have tended towards eating too many carbs – pasta’s always a lazy option.
    When I do my fast days, I generally eat the same thing – egg for breakfast and fish with veges for dinner. And I’m finding that this is influencing my taste throughout the rest of the week – I steer away from carbs and sweet things now (not entirely of course…)and physically crave the protein foods. It’s psychological too – I’m in the mindest of wanting the most bang for my bucks from each eating event and protein seems to supply that 😉 For the first time in over 30 years, I’ve had thoughts about maybe eating meat…
    I’m interested too in the science of the fast – I usually only have a break from food for 12 hours, maybe I should be trying to lenghthen that. It drives me crazy that people express interest in this diet and ask about what they should eat throughout the day in order to cope – I tell them it’s not about what to eat but about not eating (doesn’t go down well.)

    Interesting experiment NZRusty and helpful to those struggling to get high IGF-1 down. It is important to be very careful not to drop IGF-1 below recommended range as IGF-1 is essential for cardiovascular health and anything requiring anabolic processes like hormones, this is why some animal protein is included in most diets across the world.

    Eating high carbs and omega 6 fats in seeds and most nuts compound vascular risks because these foods accelerate oxidisation of tissues and also push up inflammatory hormones in the body. Focusing mostly on monounsaturated fats and relatively small amounts of fish oil are much more heart friendly.

    Frostiemama – Are you medically qualified to give this advice? If not please let us have your sources.

    I’ve been tracking protein intake, per Fontana’s reduced RDA, but have since seen reference to the difference in the manner in which plant protein (versus animal protein) is metabolized …i.e., that animal protein drives igf-1 whereas plant protein has, at least in some studies, actually lowered it ( Should I be tracking animal proteins and not worry about plant-based? I’ve not been able to find any data on that – i.e., what the rda (per kg body weight) would be for animal protein alone. If anyone has any info/studies on this, I’d be very interested to see them. Thanks…

    @rochelle do the animal proteins include fish.. is fish different..? More like plant proteins..??

    Thanks Frostiemama, I was wondering if I had been too successful if IGF-1 reduction. As per NigelWaring’s comment, do you have any sources you can cite for your comments around carbs and omega 6 fats?

    Hi Rochelle, I wish there was more information available about protein sources vs IGF-1 levels. To save time I cut protein levels AND cut out animal protein at the same time, and that certainly worked (for me). Best thing might be to experiment with your own diet and hopefully post the results here.
    Best of luck.

    I cannot find solid study material that confirms the long term effects of fasting on IGF-1.

    On the contrary, there seems to be no long-term effect:

    Also, IGF-1 alone doesn’t mean much.IGF-1 : IGFBP-3 ratio matters most in humans.

    I have been doing 4:3 since 3rd of January. I collected my blood test results on the 14th of March….and my IGF-1 was 198. In other words, intermittent fasting has not significantly reduced IGF-1 – well, at least not for me ! I still have animal protein on my feed days but substantially less than before I started fasting !

    Hi Bodhidharma, I tend to agree that Doc Mosley’s connection between fasting and IGF-1 levels appears erroneous, at least in the context of 5:2 type fasting.

    All I’ve read lead me to try 0.8g protein per KG of body weight and to make that all non-soy vegetable protein.

    That sure worked for me, with a drop from 103 to 63 of IGF-1. It would be great to hear if it works for others, but I guess it seems like a rather drastic diet change to most people.

    About your earlier point that IGF-1 alone doesn’t mean much.IGF-1 : IGFBP-3 ratio matters most. Is it generally the case that lowering IGF-1 improves the ratio?

    Do you have a source for information about this? I always suspected that just looking at IGF-1 levels was an oversimplification of things..

    Thanks for your input, Rusty.

    Thanks Rusty !!!

    I came across your post ( and I’m glad you posted !! ) after being puzzled about my IGF-1 still staying high. My 4:3 over 2.5 months was longer and more severe compared to Dr. Moseley’s 5:2 and only over 5 weeks according to his doco. His IGF-1 dropped 50% whereas mine went nowhere.

    No, I don’t have any further source of information about this. Can you please advise me the source for the 0.8g protein per kg of body weight idea – and why the IGF-1 to IGFBP-3 ratio is what matters.

    Thanks in advance.

    Hi Bodhidharma
    The above link is one of many that discuss issues around the generally accepted RDA for protein of 0.8g/Kg.

    There’s a YouTube link close to the top of this thread that makes interesting viewing.

    On the issue of IGFBP-3, I see I was confused in attributing its mention to yourself. That was mentioned in the post above yours, by BradSoltani. I know nothing of this issue.

    The thing that interests me is whether restricting your protein intake to 0.8g/Kg is the solution to lowering IGF-1 levels, OR whether restricting your protein intake to that level of non-Soy PLANT BASED protein is what is needed.

    I do not know the answer, just that the plant based route has worked for me.

    As an aside, vegan food is kinda boring, so it sure helps cure any urge to eat to much :-))

    I don’t have any answers, both fasting combined with exercising seems to offer the best benefit. Yet there are still benifits of IF 5:2 type approaches. Below is just my uneducated guessing on how they may rank at lowering Igf-1.

    Order of effect on Igf-1
    96 hour fast multiple times a year.
    96 hour fast followed by 4:3 and exercise.
    96 hour fast followed by 5:2 and exercise.
    96 hour fast followed by 4:3
    96hr fast followed by 5:2
    4:3 with exercise long term

    Weight loss
    5:2 with exercise
    Behavior benefit

    One paper that’s just come out clearly links high dietary intacts of protein (particularly animal protein – meat, milk, eggs) with increases in IGF-1 and subsequently higher rates of cancer. High protein eaters in the study were 4x more likley to get cancer, than the low protein eaters.

    However, there is a important twist: this effect only occured for people under 65 years old. For older people it was actually healthier to eat more protein as IGF levels fall with age, and then presumably muscle wastage and increased falls and decreased mobility and the like have a greater impact on life expectancy.


    Cell Metabolism
    Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population
    Morgan E. Levine, Jorge A. Suarez, Sebastian Brandhorst, Priya Balasubramanian, Chia-Wei Cheng, Federica Madia, Luigi Fontana, Mario G. Mirisola, Jaime Guevara-Aguirre, Junxiang Wan, Giuseppe Passarino, Brian K. Kennedy, Min Wei, Pinchas Cohen, Eileen M. Crimmins, and Valter D. Longo

    Mice and humans with growth hormone receptor/ IGF-1 deficiencies display major reductions in age- related diseases. Because protein restriction reduces GHR-IGF-1 activity, we examined links between protein intake and mortality. Respondents aged 50–65 reporting high protein intake had a 75% increase in overall mortality and a 4-fold increase in cancer death risk during the following 18 years. These associations were either abolished or attenuated if the proteins were plant derived. Conversely, high protein intake was associated with reduced cancer and overall mortality in respondents over 65, but a 5-fold increase in diabetes mortality across all ages. Mouse studies confirmed the effect of high protein intake and GHR-IGF-1 signaling on the incidence and progression of breast and melanoma tumors, but also the detrimental effects of a low protein diet in the very old. These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.

    There is some evidence that the amino acid, methionine, which is particularly present in animal protein (meat, eggs and milk) could critical to keeping IGF-1 levels high – even though soy is high in Met, it’s still relatively low compared to other sources. This opinion piece summarizes things well:

    The low-methionine content of vegan diets may make methionine restriction
    feasible as a life extension strategy
    Mark F. McCarty *, Jorge Barroso-Aranda, Francisco Contreras
    Medical Hypotheses

    Recent studies confirm that dietary methionine restriction increases both mean and maximal lifespan in rats and mice, achieving ‘‘aging retardant” effects very similar to those of caloric restriction, including a suppression of mitochondrial superoxide generation. Although voluntary caloric restriction is never likely to gain much popularity as a pro-longevity strategy for humans, it may be more feasible to achieve mod- erate methionine restriction, in light of the fact that vegan diets tend to be relatively low in this amino acid. Plant proteins – especially those derived from legumes or nuts – tend to be lower in methionine than animal proteins. Furthermore, the total protein content of vegan diets, as a function of calorie content, tends to be lower than that of omnivore diets, and plant protein has somewhat lower bioavailability than animal protein. Whole-food vegan diets that moderate bean and soy intake, while including ample amounts of fruit and wine or beer, can be quite low in methionine, while supplying abundant nutrition for health (assuming concurrent B12 supplementation). Furthermore, low-fat vegan diets, coupled with exercise training, can be expected to promote longevity by decreasing systemic levels of insulin and free IGF-I; the latter effect would be amplified by methionine restriction – though it is not clear whether IGF-I down-regulation is the sole basis for the impact of low-methionine diets on longevity in rodents.


    Thank you for the information!

    Putting it into some framework for discussion, we can see why 5:2/4:3/ADF may help longevity – they seriously reduce protein intake on the diet days and thus reduce overall protein intake.

    It also suggests that those over 65 need to ‘supplement’ their diets with additional protein if they are also following one of the IF diets.

    It has long been known that too much protein (over about 35% of calories from protein) is associated with physical distress, which disappears when protein intake is reduced. Current dietary standards recommend you get about 20-25% of your daily calories from protein. The information you have given does not address how much protein is ‘too much’, so it is not clear to me, at least, whether current guidelines are too high.

    Finally, we are at a point in time where other research is showing the importance of fats in the diet and the harmfulness of carbs. If a person is going to reduce calories from protein, then it would appear their fat intake might have to increase.

    All very interesting!

    Thanks Rusty for the info !!!

    Read Forks over Knives and The China project. This is nothing new.
    Happy fasting!!!

    @simcoeluv: Glad the information was helpful.

    The groups in the Cell Metabolism were divided into three groups: Low (<10% protein by calories); Medium (10%-20% calories by protein); and High (>20% protein by calories).

    It was the Low vs the High group had a 4x reduction in cancer incidence.

    I am not sure I buy the idea that carbohydrates are bad for you, so long as your overall BMI remains healthy.

    The paper can be downloaded for free here:

    Thanks RadiantFlux. That’s just the kind of research results that offer encouragement for continuing on my current path.


    In 15 years I can ramp up my protein intake and hopefully enjoy a healthy old age with all the delicious food back on the menu.

    Thanks again, you’ve made my day.

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