What are the benefits and risks of fasting?

What are the benefits and risks associated with fasting? Fasting over the past few years has become pretty mainstream with various iterations featured in books that grace the shelves of high street shops. Popular versions include 16/8 where you don’t eat for 16 hours and limit your intake to an 8 hour window, 18/6 same but longer restriction period, 5/2 this is 5 days of normal eating and 2 days of 5 to 800 calories. The eat fast eat methods all come under the umbrella of intermittent fasting. Then there are the longer or prolonged fasts and fasting mimicking plans such as Prolon which is a scientifically designed very low calorie plan.

Claims made by proponents of fasting include:-

Improved fat burning

Improved weight loss

Reduced risk of cancer

Optimized hormone levels

Improved cholesterol levels

Improved body composition

Better blood sugar regulation

Reduced risk of heart diseases

Increased activation of stem cells[1]

All sounds pretty amazing doesn’t it? Especially if it’s just a case of skipping breakfast! Except the science is not yet behind the idea of intermittent fasting, in fact a year long study disputes the majority of the claimed metabolic benefits[2][3]

Photo by Elle Hughes from Pexels

That is not to say there are no benefits and that if you personally find it helps with weight loss, calorie maintenance or feel it suits your lifestyle that you should give it up. The science is also not entirely conclusively against intermittent fasting, for example a study of breast cancer survivors found that those who had more than 13 hours between the last time they ate in the evening and the first time they ate in the morning was associated with a 36% reduction in the recurrence of breast cancer.[4] It would seem that our bodies being constantly bathed in calories is not long term good for us. It needs periods of rest and recovery.

However, it looks unlikely that some of the really interesting aspects such as autophagy take place over such short periods of restriction. Autophagy translates as self eating, in this process when the body is not taking in enough calories in particular it seems proteins it will scavenge it’s own system in order to find the necessary proteins. In particular damaged cellular matter is broken down first, this makes sense, if we face financial hardship we will mend or repurpose damaged items while leaving new perfect goods alone.

It is the process of autophagy where the real magic of fasting lies, through this process we can reduce inflammation, reduce our risk of tumors, delay the aging process and increase the production of tumor killing cells.[5]

When fasting is combined with chemotherapy it seems according to some studies reduce the risk of side effects by sending the healthy cells into a protective state while leaving the fast growing mutation cells open to attack.[6]

Photo by Engin Akyurt from Pexels

It’s all pretty exciting stuff really and a great deal of research is currently going on looking at various medical applications of both fasting and fasting mimicking diet. The fasting mimicking diet is the brain child of Professor Valter Longo and allows for a small almost protein free intake of calories over the fasting period.[7]

The caveat in all this is that it takes at least 2 to 4 days for this to take place and not the few hours of restriction we were all hoping for.[8] The ideal period of fasting is around 5 days.

It should be noted that autophagy can also be triggered by long periods of calorie restriction which may be a more suitable path for many, in order to trigger autophagy a restriction of 40% of normal intake is necessary, so for example if your intake is 2000 a day reducing it to 1600 for a few weeks will result in a degree of autophagy[9]. I will likely write a separate post on this another day.

Such longer term periods appeal to me less purely because at the moment training is very important to me which means I eat at or slightly above  maintenance calories which supports my energy and post training recovery. Fast and hard is my preferred method (pun intended) to this and many aspects of life.

I have used Longo’s fasting mimicking plan a few times now, 4 maybe 5 times I can’t quite remember. The last time was nearly 9 months ago! I had planned on before Christmas but family responsibilities, social engagements etc meant I kept having to bump it forward. I set a specific date for Feb, which is next week, put it in the calendar and turned everything that tried to crop up down other than a couple of non-negotiable appointments for my daughter!

I prefer during fasting weeks to turn life down, I did during my first one attempt to train and live as normal and by day 4 I felt awful. I mean really really awful. After that experience the next attempts were undertaken a little more sensibly. I take the week off work and focus on nurturing myself and allowing for rest while I push my cells into a repair cycle. I think it’s reasonable to allow myself time to do this and as it’s 2 to 3 weeks in a year maximum stepping back a little is no bad thing. It’s also one of the many benefits of being self employed! Plus if it gives me chance of

Of course it is necessary to mention that fasting and fasting mimicking plans are not without risk, during the 5 days it is possible to experience fatigue, dizziness, feeling cold and of course hunger. As I mentioned earlier when I pushed too hard I did feel genuinely dreadful and learned my lesson. The biggest risk however is something called re-feeding syndrome which can be deadly

“Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally). These shifts result from hormonal and metabolic changes and may cause serious clinical complications.”[10] It is rare but necessitates that the two days after fasting involve a gentle re-introduction of food rather than rushing to McDonalds for a big mac. It is less likely with the fasting mimicking plan due to the very small caloric intake keeping the digestive mechanisms running. However they still recommend a slow return to nutrition.

Photo by Krishnajith from Pexels

There are a number of scientists working in the realm of aging and longevity all with different ideas and methods, however one area in which they all seem to agree is that short periods of fasting (5 days for full benefits) are one of the most reliable methods of reducing disease risk and promoting a longer healthy life. Nothing in life is guaranteed, but if a short period of discomfort can shift the odds in my favour I’m all for it! See you on the other side!

[1] https://www.doctorkiltz.com/16-8-intermittent-fasting/

[2] https://www.nytimes.com/2022/04/20/health/time-restricted-diets.html

[3] https://www.nature.com/articles/s41574-022-00638-x

[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4982776/

[5] https://www.cell.com/cell-metabolism/fulltext/S1550-4131(15)00224-7

[6] https://www.cell.com/cancer-cell/fulltext/S1535-6108(16)30265-3

[7] https://www.valterlongo.com/fasting-mimicking-program-and-longevity/

[8] https://www.medicinenet.com/how_long_do_you_need_to_fast_for_autophagy/article.htm



Last picked for every team

Some people excel at sport and athleticism from an early age, it is woven into their DNA. They take to any physical activity they try with ease and grace. The kind of people who won every race at sports day and captained every team. Then there’s those like me who were quite literally picked last for every team in PE, I swear to god if my classmates could have chosen the school bench over me they would. To be fair it would have probably done a better job at the time.

I was skinny, knock kneed, had an undiagnosed hypermobility spectrum disorder and the serious lack of muscle tone that goes with it. As is often the case when we are awful at something I avoided it like the plague, I don’t know if things have changed but in my day PE teachers had no interest in those without natural athleticism never mind the reasons why.

To be entirely honest my experiences at school with regard to fitness were not just negative they were actually traumatic. I was openly bullied for my lack of physicality and knock knees and viciously name called. I’m not sure though out of the laughter or the pity clap I would sometimes get coming in dead last for something…again which one was worse. I still won’t even so much as take part in a 5k race in public as a result, the idea of any type of competition fills me with horror to the point where I actually feel physically sick.

Why am I telling you this? It’s not for pity or sympathy, I am honestly quite fine. The past is the past. I want you to read this if you like me had no natural ability and let you know that it does not and never did exclude you from looking after yourself physically. No matter how rubbish you were at PE you can still benefit from various forms of movement. Heck you might even enjoy it. I certainly do, in fact I can’t imagine a life where I don’t get up and exercise pretty much every day. I am so grateful that I discovered first yoga and Pilates in my 20s which I found I actually quite naturally built for and being the antithesis of competitive sports allowed me to tune in with my body and learn to love moving it. It was this love of movement I took into CrossFit and strength training, the difference being in that situation I was pretty rubbish to begin with. However many years later of keeping at it I am actually

pretty strong and certainly fit.

That for me is the important aspect, being fit and healthy, being strong enough to squat down to the ground with a heavy back pack and stand back up, being able to walk briskly up hills without losing my breath, being limber enough to fold into my legs with no discomfort, being able to lift heavy suitcases over head for other passengers on trains. These are the things that matter to me. That and the sheer love of movement, oh heavens it is simply glorious to just move, there is a delight in using your body that is with language almost inexpressible. As though different movements all have their own flavor and to engage in more than one is like a banquet for the body. Plus as a result I honestly feel better at nearly 50 than I did my entire adult life.

Don’t let a perceived idea of not being athletic dictate to you that exercise isn’t for you, it is for everyone from those like my husband who are naturally talented in a particular field (running) and thrive in competition to those like myself who myself who had to work at it. In fact I think those of us who are not naturals potentially benefit even more as there are often underlying conditions that make us that way which are improved by movement.

Exercise is for all of us and is certainly one of the keys to health and longevity.

If you are considering getting moving and would like a little support either in person or virtually get in touch.

Why I am walking a minimum of 15000 steps a day for a year

And I would walk 15000 steps, and I would walk 15000 more…Just to be the one who walked 15000 steps a day or more. You are very welcome for the brain worm I’ve implanted, now lets get on.

Photo by Tatiana Syrikova

As I mentioned in my post on Blue Zones aside from eating a diet devoid of processed food and high in vegetables plus fruit the centenarians moved a huge amount throughout their entire lives. In fact they on average only rest for 8 to 9 hours a day and that includes sleep, most of it is low intensity gardening, walking place to place with distances of 7 to 9 miles not being uncommon. Compare that to the UK where the average step count is a paltry 3000 to 4000 a day[1]

Photo by Alex Azabache

Movement throughout the day or Non-Exercise Activity Thermogenesis (NEAT) has a huge impact on weight, insulin sensitivity and metabolic health.[2] But I exercise I hear you cry, the question then is if we go to the gym a few times a week does that actually make up for spending the rest of the time sitting? Apparently not, if after a bout of exercise, the rest of the day is spent sitting or driving you are still losing out on your primary method of thermogenesis (calorie burning) and as a result are still at risk of a number of metabolic diseases[3]. In fact even in elite athletes sedeantary time outside of training leads to increased abdominal adiposity[4] leading the researchers to conclude

“These findings indicate that athletes with higher amounts of sedentary behaviour presented higher levels of total and trunk fatness, regardless of age, weekly training time, and residual mass. Therefore, even high moderate-to-vigorous physical activity levels do not mitigate the associations between sedentary behaviour and body fatness in highly trained athletes.”[5]

As the average age of the cohort researched was 22 this is a little concerning!

It’s not a huge surprise, then that as a nation we are getting bigger, and we are also in general getting sicker.

As hunter gatherers we would have averaged around 16 to 17000 steps a day, we would also have carried chopped and engaged in other physical activities, there are tribes who still live like this although they are becoming a rarity, when moving this much and this often-cardiovascular disease is rare[6] Perhaps it is not the type of exercise or movement we engage in that matters but how often we move, it will come as good news to those who don’t enjoy exercise that you don’t need to engage in vigorous activity either to benefit, you just need to move often. Although I would always recommend both strength training and mobility training for optimal aging.

Photo by SHVETS production

In more recent times such as the 1950s women were estimated to burn around 1000 calories on top of their basal metabolic rate (the calories needed just to exist) through walking, cleaning, cycling and other activities.[7]  While men depending upon their profession could burn more through their work and commute to and from work. Few people had cars, most lived close enough to their place of occupation to walk to and from work and children would be unlikely to get to school any other way than by foot.

Now I am not suggesting we relinquish cars, washing machines and all return to working as Shepherds (though it does sound pretty idyllic) but it is clear we move less than we ever have and the truth is it is not doing anyone any good.

Photo by Rachel Claire

I came to the realisation that I was not immune from this sedentary behaviour, I like to think I am relatively fit for my age, I strength train, use a stationary bike 4 or 5 times a week, CrossFit regularly, practice yoga and walk the dog. But the truth is that although I exercise daily and walk the dog on top the rest of the day I am sat down, I am working towards my PhD which is of course desk work and I now teach and train people primarily from home.

Like a lot of people then my movement has dropped. I want to stay as healthy as I can for as long as I can and do what I can to promote a long healthy life. I decided then mid October to walk a minimum of 15000 steps a day. This is based on research on postal workers that found 15000 steps was optimal for blood pressure reduction, cholesterol reduction and many other health benefits[8] I decided initially on a period of 9 months which would take me to my 50th birthday. I then changed that to a year. I believe that to fully appreciate the benefits of any change we have to commit to a reasonable period of time as these types of changes don’t happen quickly. I am particularly interested in changes to my blood pressure, since surgical menopause it sometimes creeps higher than I would like. Not high enough for a doctor to be concerned they reassure me, but outside of the bounds I would be comfortable with. According to the American College of Cardiology a higher step count is linked to lower blood pressure.[9] I would also like to see a reduction in cholesterol, on my last check my levels were at the upper end of ok.

The rules I set myself were as follows:-

  1. Any “steps” count for example if I cycle 15k on my bike erg my watch will register around 5 to 6000 steps. This is helpful as due to caring responsibilities I cannot always leave the house. It is important that any goal we set is achievable and fits into the life the live not the life we would like to live. Equally all steps around the house, shopping etc count. It is simply the total step count at the end of a day.
  2. I am aiming for 90% compliance across the year, as with everything consistency is more important than perfection. There will be times I have responsibilities to others or it might be inappropriate to go for a walk, or when I am too unwell.
  3. I will continue to exercise and eat pretty much as I was, this for the year is the adjustment I am making.
  4. Each day has a target of over 15000 regardless of the previous day, I am not averaging across the week. So, for example if one day is 22000 steps it is irrelevant to the following days activity, I still aim for the 15000 steps. My logic on this is that if I lived in pre-industrial environment I would still need to fetch water and food that day regardless of what I had done the previous day.

I am currently at the end of 4 months and on average have exceeded my target with an average of 17000 to 18000 steps a day and within the 14 weeks have missed only one day.

That day was the day we were traveling on holiday and although I was at 11000 steps it was way too late when we arrived at our accommodation to try explore a new place. Still 1 day missed in 14 weeks is pretty good if you ask me. Things I have learned during this time trying to get over 15000 steps:-

November, December and January
  1. Some days it’s really easy, I will be on the bike in the morning, walk the dog, train a couple of clients, run some errands and before I’m at 1 pm I have already hit the target.
  2. Other days it’s really hard, as in oh my word how many more do I have to do today, how am I not there already and do I really need to go back outside? Really?
  3. For me it is important to be entertained, to fit in the bike and/or walking it is part of my relaxing time, what this means is when I am on the bike I watch tv. I particularly enjoy shows with subtitles as being on the bike means I am captive in my focus, currently I’m working through a selection of Korean sci fi/supernatural dramas. Walking it’s podcasts or books, I will only listen to those books or watch those shows when I’m biking or walking. That way I actively look forward to getting back into my book and the walking is almost subsidiary. If you walk occasionally in the countryside on a beautiful day it may well be enough to just listen to the sounds of nature, if you are planning on walking every single day, in the rain, in the dark, in the snow often next to noisy dirty roads in order to fit it in the sounds around you may seem less attractive. Find something to entertain you!
  4. Having this challenge has meant I have walked on days I would not have otherwise, when I am tired or under the weather. In the past I would have asked someone else to walk the dog, but I remind myself that if I lived in a hunter gatherer community or was a shepherdess I would only take days off if I literally could not move. You would not just stop for feeling a little under the weather. Granted those days are not dynamic walking but I am up and moving. This week for example I have a nasty sinus thing going on, I am not well enough to train or do much really but walking is so much of a neutral activity now I have been able to slowly shuffle around and get my steps in.
  5. I don’t actually weigh myself as it’s  not a metric I am particularly interested in but I have lost weight, some clothes have become looser and snug waist bands now are somewhat baggy.
  6. My cardio has improved significantly, I walk brisker than ever with little effort and don’t feel at all breathless up hills

I am leaving measuring blood pressure etc till much later in the experiment, I will be getting I believe a full MOT at 50 which will be a good time to check over all my health stats and as it will be 9 months since I started this experiment will be a good time to assess how I am doing!

If you are reading this, start tracking your day to day movement with phone, watch or pedometer and find out how active you are outside of formal exercise.

[1] https://www.bbc.co.uk/news/magazine-33154510

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6058072/

[3] https://journals.lww.com/acsm-essr/Fulltext/2010/07000/Too_Much_Sitting__The_Population_Health_Science_of.3.aspx

[4] https://www.tandfonline.com/doi/abs/10.1080/02640414.2014.926382

[5] https://www.tandfonline.com/doi/abs/10.1080/02640414.2014.926382

[6] https://link.springer.com/article/10.1007/s42978-020-00091-0#:~:text=Male%20and%20female%20hunter%2Dgatherers,in%20the%20tribe%20%5B29%5D.

[7] https://metro.co.uk/2022/06/15/this-is-what-diets-and-lifestyles-were-like-in-the-1950s-16826401/

[8] https://pubmed.ncbi.nlm.nih.gov/28138134/

[9] https://www.acc.org/latest-in-cardiology/articles/2020/03/18/15/42/step-it-up-higher-daily-step-counts-linked-with-lower-blood-pressure-acc-2020?fbclid=IwAR1Aoh0MT2d7VxdfDfubRKRL8RDAUTCfJBW_JcXFI2y8NAkOjYWt0kV6-2s