After 5 months on the diet I would say the opposite to your friends .my husband and I have both commented in the last week how our immunity has improved. No colds or other seasonal illnesses….our osteopath also confirmed this has been the case of others 5:2 s he sees.
I’d be interested in scientific studies on this. Maybe Michael has some references I seem to remember from the book and the Panorama Program it has been shown IF in mice leads to increasd immunity?
We are Australians not vegetarians although we eat a lot of veges from the garden. We fast on Tuesday and Thursday although we do change for social occasions and have lost 24 and 21 lbs in the 22 weeks on 5:2. My cholesterol has gone from 5.9 to 4 and my liver function 100% improved although I don’t drink alcohol I had hepatitis A twenty years ago. Interestingly I have been on thyroxine for 20 years with almost no change but after 3 months on 5:2 the dr reduced my thyroxine dose as my body was metabolizing so much better I didn,t need as much.

For the last 20 years or so I seemed to get every virus going, especially throat infections, and I’d take ages to recover from them. It got to the point that I wouldn’t book anything a long time in advance – especially if I needed to try to get reasonably fit before hand like a ski-ing holiday. I was under a fair amount of job-related stress for most of this time which obviously didn’t help. I was twice diagnosed with post-viral fatigue syndrome which took up to 6 months to recover from. Most recently I suffered from 2 panic attacks, 6 months apart, and needed cognitive behavioural therapy to help avoid future such attacks. At one point I ended up having 6 operations in 4 years, including getting my tonsils out – damned painful as an adult. Overall my health was a mess and I was getting fearful of going to public events for fear of catching something else. I had loads of blood tests, none of which ever produced any conclusive results at all.

Almost exactly 6 months ago I started doing the 5:2. I’ve lost 2.5 stones; my waist is about 7″ smaller – and I haven’t had to visit my GP, nor been off sick at any time, for the whole period. It may be coincidence but I am convinced that the 5:2 has given my body time to repair DNA/cell damage and that my immune system is working better than it has for over 20 years.

I certainly feel better and more energetic than I have in decades – recently starting a much less stressful job no doubt also helps, but that was only 1 month ago and for the previous 5 months I was unemployed and wondering if I’d get a job at all. Hence I believe the 5:2 has not only got my weight back to where it was about 38 years ago when I was 12, but has also made my overall health better than it has been in decades. I recommend it to everyone.

I just hope the 6:1 will have the same beneficial effects.

I rarely get ill and started the 5:2 diet as an experiment.
I’ve been doing it since June/July this year.
Within the last month, I’ve had a cold & cough and norovirus,
plus an injured tendon on the top of my foot,
stopping me from running for a few weeks so far.
I’ve been running for 1.5 years and haven’t had an injury that persistant yet, as I am careful not to overdo it.
I can’t claim the 5:2 diet is the cause,
but have definitely been wondering if it is lowering my immune function & physical resilience.
I haven’t changed other areas of my life and could probably do with earlier nights, especially on fast days.
The post by Donald makes the most sense to me:
I don’t enjoy being hungry two days a week and sometimes can only do one day properly,
the second being like a “semi fast”. I don’t see the point in causing that much stress to my body.
I’d like to see more varied, long-term evidence for this way of eating.
As a mostly vegan beginner-runner, not significantly overweight, no previous health issues other than depression; over 40 and female, I wonder if it’s not so much the fasting I need,
as to be more mindful of my eating habits all week through, without causing myself the stress of starving.
I also abhor calorie restriction as a way of life (I’m not referring to the 5:2 diet here because once I know the amounts of things I can eat I don’t count anymore)
It just might be that fasting is good for certain body/lifestyle types, or people with stronger mental health and not such a good idea for others. I would love to know if the 5:2 diet IS responsible for the lowering of SOME participants’ immunity – perhaps further research with be more thorough and conclusive.

Interesting question. A couple of ideas. 1) the less we eat the more important the nourishing value of the food for our body constitution. Finding and fulfilling the depletion holes in our immunity. 2) Fasting is a detoxing and detoxing is a process of releasing accumulated toxins in the body. The more toxins released the worse we feel. And if we are not properly removing them the bigger the havoc they create.

@bigbooty
Quote: “If you let it stress you then it WILL stress you. It is the stress which is playing havoc with your immune system not the fasting per se’.”

I’ve remembered this from dr Fung:
https://www.dietdoctor.com/suggestions-improve-sleep-fasting

“Should you fast if your cortisol level is high?

My cortisol level is 913, but it should be between 150-660. I’ve read that hunger increases cortisol. Are there optimal ways of fasting? Is fasting longer than 24 hours acceptable?

My insulin levels are also high, and I’m working on it with LCHF.

Thanks,
Sabina

Dr. Jason Fung: Yes, fasting may increase cortisol, which is one of the counter regulatory hormones that is meant to increase glucose in the blood during fasting. Whether it is safe depends upon your medical history, and you would need to discuss with your doctor.”

And here about some patients of Dr. Kresser:
https://chriskresser.com/intermittent-fasting-cortisol-and-blood-sugar/

“So, while I agree that IF is part of our heritage, and that it can be helpful in certain situations, I don’t believe it’s an appropriate strategy for everyone.

Why? Because fasting can elevate cortisol levels. One of cortisol’s effects is that it raises blood sugar. So, in someone with blood sugar regulation issues, fasting can actually make them worse.

I’ve seen this time and time again with my patients. Almost all of my patients have blood sugar imbalances. And it’s usually not as simple as “high blood sugar” or “low blood sugar”. They often have a combination of both (reactive hypoglycemia), or strange blood sugar patterns that, on the surface, don’t make much sense. These folks aren’t eating a Standard American Diet. Most of them are already on a paleo-type or low-carb diet. Yet they still have blood sugar issues.

In these cases, cortisol dysregulation is almost always the culprit. When these patients try intermittent fasting, their blood sugar control gets worse. I will see fasting blood sugar readings in the 90s and even low 100s, in spite of the fact that they are eating a low-carb, paleo-type diet.”

Sorry. Now I see that you are also “mostly vegan”. Long term, that may also have negative health consequences, if your diet is not proper balanced.

@adaline I think most people think that doing IF is going to fix everything overnight. It wont and its a very long road to recover for your system. I remember my initial fasts and they were unpleasant. Bad taste in my mouth, lower back pain (I suspect kidneys), diarrhea, etc. It took months to stabilise. Perhaps sneak up on IF and give your system a chance to get used to it. Try 16 hours, that really shouldn’t be too hard, its the equivalent of having your breakfast slightly late. Have dinner the night before at 6pm. Go to bed. Wake up and don’t have breakfast until 10am. Heck I sleep in on Sundays till 10am and I don’t even consider that to be a “fast” but its been 16 hours. Then slowly try and increase the time intervals. Try going to mid day. Then till 2pm etc. If it doesn’t work for you then stop. But try doing it for several weeks before saying it doesn’t work.

My opinion is that it comes down to stress. Mark Mattson likens fasting to exercise, and it’s a very good analogy because fasting and exercise trigger the same metabolic processes.

If you exercise too much, you’ll start getting injuries and get sick. Conversely, we all know a good amount of exercise helps the immune system. Just the same with fasting. I would speculate that people who start getting sick with fasting have some combination of

1) not enough reserves (e.g. fat) to get them through the fasting periods,
2) insufficient nutrient density on feeding days
3) too much exercise
4) too little sleep
5) too much stress

If I were getting sick and injured more than usual while fasting, I would take a break from it or switch to 1/week, and incorporate meditation and other stress reduction. I love the Headspace app for meditation.

Vegan/vegetarian diets aren’t for everyone. I was a vegetarian for 20 years until I developed/discovered intolerances for wheat, dairy, and beans. I wonder if the people experiencing problems have a very high carb/starch diet. Perhaps substituting more eggs, dairy, and veggies would help.

@lemna – good points made there.
I think my recent bouts of “ailment” come down to a combo of all those five points.
Seems I was winging it on 4 points, but the fasting was maybe the last straw – ultimately it may’ve helped reassess some unhelpful tendencies.

I agree that veggie/vegan might not be for everyone. I don’t do well on meat dairy at all, conversely! I know a lot of vegans go for the high carb option – at best I am quite well balanced but you may have a point you know, about carb/prob correlation – I’ll keep an eye on that as I do love to have healthy starches.

@adaline & @bigbooty – thanks for all you recent quotes and posts -will read asap! I am also intuitive in my approach to eating/fasting/exercise but probably push things at times + probably over-feast on feeding days, but it’s a new trial so just observing my tendencies, not beating myself up.

@bigbooty – ah, the cold showers. I’ve done a regular cold water paddle in the bath every morning in the past – increasing to sitting in it then I’m not sure I got to full immersion! I also tried cold showers. Currently live in north yorkshire on a key meter – cold showers just seem like hell to think about at the moment! 😀

Thanks again everyone.