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.

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. 🙁

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 Jono,
I lived in France for 13 years and still run a business there near Poitiers..you’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 !

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 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 http://www.labtests.co.nz/index.php?option=com_content&view=article&id=28&Itemid=135.

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 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.

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 http://en.wikipedia.org/wiki/Complete_protein 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)

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.

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 http://www.juststand.org/ 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

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.

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 (http://nutritionfacts.org/2013/02/14/animal-protein-and-igf-1/). 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…

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:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2673798/

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

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.

See:

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.

Thanks Rusty for the info !!!

@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: http://dx.doi.org/10.1016/j.cmet.2014.02.006