Fasting Mimicking Diet, type 1 diabetes & endurance running  

There’s a catchy title hey? The Fasting Mimicking Diet, or FMD, has been researched and developed by Dr. Valter Longo. It is less of a diet and more of an intervention. By restricting caloric intake and managing macronutrients (protein, carbohydrate, fats etc) within a particular ratio, the practitioner (you, if you’re giving this a go) triggers certain beneficial stress responses in the body.

I first heard of this intervention by listening to Longo on Rhonda Patrick’s Found My Fitness podcast. I highly recommend the audio over the video, perfect for a run or long drive. Her conversation with Joe Rogan was the first time I’d heard of her, and I’ve listened to her regularly since.

And here is Patrick’s first interview with Longo, laying the basis for his research approach back in 2016.

The basic principle is this – given that the human body displays many beneficial regenerative processes during prolonged fasting (more than 3 days), and given that we’re seeing a global epidemic of ill health especially in westernized civilizations, it is possible that the body has evolved over a very long time to benefit from a recurring limited availability or intake of food that has only become a non-occurrence within a very short period of time, relative to human existence.

But, fasting on only water for much more than a day has a very low compliance rate. Even in patients who are out of options, Longo found that adherence to prescribed 5-day fasts was low. That’s right, people are less scared of dying than of missing out on chocolate.

So he developed the FMD as a way to achieve the physical benefits of a fast without the total suffering and inconvenience of zero food for 5 days.

“Alright, I’m interested, but what are these benefits?” you ask. Great question.

Essentially – reduced inflammation throughout the body, reduced insulin resistance (these two go together almost always), reported doubling of stem cells (see The Longevity Diet, Longo), renewal of high per centre of white cells, weight loss.

Those are the least complex immediate benefits and more than enough reason to want to try the process for yourself, whatever your state of health. The FMD is recommended as a twice yearly act of maintenance for people in good health and something that can be done 6 – 12 times a year by people with deeper health issues ranging from type 2 diabetes to much more serious conditions. In The Longevity Diet, Longo details the benefits of the FMD when used in conjunction with chemotherapy with some statistically significant results.

Longo explains the action of the FMD on the body with an analogy about ancient armies. Paraphrasing, if the Carthaginian army were to fight the Roman army it would be hard to tell them apart because of similar uniforms. However, explains Longo, if someone were to shout ‘Kneel down!’ in Latin, the Romans would understand and drop to one knee, leaving the Carthaginians exposed to arrows (chemo) fired by archers (doctors). Healthy cells in the body react to the FMD by shielding themselves, whereas deranged or dead cells are left exposed and easily identified by processes of regeneration or elimination.


For myself, the idea that autoimmune conditions have been genetically existent for millennia but only really exploded in the last century was novel. This was probably the trigger that made me want to try the FMD. Also, breaking my finger in a trail-running stuff-up on Boxing Day, more stem cells sounded like a great idea. Longo’s notion that periods of sustained not eating are something the body has evolved to, not only benefit from, but also need for healthy maintenance is a compelling hypothesis.

Originally I was going to get hold of the PROLON meal kit that has 5 days worth of food, exactly the same as the meal kits used in clinical settings by Longo and his team. But when I was referred to the Australian supplier they weren’t just out of stock, they require a doctor’s note if you tell them that you have any kind of health condition. They did not respond positively to being told that for someone selling low calorie mealboxes they could really try act less like someone’s intrusive parent. My general tip would be to try not patronising self-reliant people with your cliched perception of their health condition and see how far that gets you.

So, having saved $USD250 I went with Plan B. (Most of this money goes into a healing and research oriented foundation which is great, but I also think the pricing is oriented toward the affluent ‘I wanna live beautiful forever’ west coast US market). Talking with Kerry Suter from Squadrun about how he had done the FMD on his own terms I settled on a basic meal plan. Kerry’s golden nugget of advice was to create a white list of things I would eat rather than a blacklist of things I couldn’t eat. This mental approach is, I think, key to being successful with as little stress as possible in undertaking the FMD. Daily, I would put my intended food intake into the MyFitnessPal app (thanks for tips and other great tips Hailey) and make sure it was close to 700kCal for the day.

Taken from The Longevity Diet by Dr Valter Longo, this is the definitive overview of what goes into the FMD. Buy the book, it’s an invaluable resource full of useful advice and beautifully expressed insight.

Longo’s FMD calls for 1100kCal as a way to ease in on day one and then 800kCal days 2-5, with sensible and gradual reintroduction of higher calorie meals from day 6 onward. But by setting my daily goal at 700kCal it was easy to not go over the recommended intake and jeopardise the total benefits that only really start to kick in from Day 3. Day 1 was physically challenging, with a growling stomach well aware of how much I wasn’t eating. Day 2 was more about the distraction of food billboards and pictures of meals online. After that it was actually easy.

Other elements of Vongo’s research also reinforce, mentally, the value of the process. Two groups, one which undertook a 5-day FMD, one on a standard diet, were given the same amount of total calories over a month. The group that had undertaken the FMD lost more weight than the one that hadn’t. A commonsense interpretation would simply be that the intervention restores certain processes in the body so that it works better after the FMD than before.

Listening to Satchin Panda discuss circadian rhythms and their impact on health, from Day 3 I also kept my eating within a 10-hour window from first non-water mouthful of the day to last. Longo is anti-coffee but I did go with short black decafs that I don’t think did any harm. The tocopherols in decaf apparently stimulate autophagy (cleaning up by the body of dead or broken cells) so I felt like that was a beneficial compromise between what I wanted to have and what I wasn’t meant to.

Meal intake was essentially
Breakfast: half a can of organic lentils with half a medium avocado and a teaspoon of olive or coconut oil, plus multivitamin and Omega-3 capsule.
Daytime: 45-50g raw cashews, plenty of water, and a constantly present thermos of peppermint or ginger-lemon tea.
Evening: half a bag of Pitango pumpkin and ginger soup, sometimes with a ripped up handful of kale for extra fibre



Day 1 – weight 93kg
Day 5 – first run of the week (I didn’t want to jeopardise the experiment by going hypo early in the process by having to take in extra calories). 8km run/walk on treadmill with incline over 65min. Energy felt consistent, steady sugars, not even hungry afterward, ate first food of day 2 hours later. Same on Day 6.
Day 6 – 87.5kg. Beginning of crucial refeeding and recovery process.

3 weeks later – weight holding steady at 89kg.

Running during FMD

I chose not to run during the main period of the FMD, because I didn’t want to get to day 3 when things were finally starting to happen and have to scoff jelly snakes in the middle of a forest somewhere just to be able to make it home, having also disrupted the entire process only to have to start again.

I did run on treadmill on Day 5. Straight out of bed, unfed, on a 4% incline I ran/walked about 8km in 65 minutes. There was no feeling of tiredness in the body, and as expected joints were actually quite open and moving well. This is a typical observation during a multi day fast. Sugars slowly began to increase after about 45 minutes (more likely 25 minutes, Freestyle Libre is the best option in my world for measuring sugars but needs to be used with an understanding that the number on the screen reflects what sugars were a quarter of an hour ago, and that trends mean more than single values). I felt no need to eat until 2 hours after running. It’s interesting listening to Rhonda Patrick that the whole idea of needing to get protein into the body within a narrow window right after training has also now been debunked.

Day 6 also featured a morning treadmill run, fasted from sleeping. I added faster intervals, 300-400m at 14-18km/h, punctuated by hiking and jogging. The total time and distance for the session was the same as for Day 5. I sweated profusely early but did not feel any degree of unwillingness from my tissues to suffer. If anything I was conscious that the core work I did last year leading up to Hardrock 100 has been badly neglected and needs a revisit. Again, sugars climbed in the latter section of the run, on the basis of monitor lag, adrenalin, and Levemir diminishing with passing of time.

Training fasted, especially exerting and suffering fasted, has been identified as a beneficial stressor, increasing mitochondrial efficiency. I could finally understand our friend Andy Hewat’s commitment to long fasted morning runs, and will be including this approach in my training from now on. Metabolising natural fat stores requires less water than digesting and metabolising carbohydrate, so there is a decrease in thirst before carbs or introduced and also from blood sugars not rising to the level that every type 1 recognises as a cottony and unquenchable thirst.

Levemir intake during Fasting Mimicking Diet starting 7/1/19

Day 1 5u morning, 4u evening

Day 2 3u morning, 2u evening

Day 3 2u morning, less than 2u evening

Day 4 1u morning, less than 2u evening

Day 5 less than 2u morning, less than 2u evening

Insulin intake was tapered off during the week with sugars becoming increasingly stable. Typically I take 10 to 20 units of Levemir as basal insulin per day with anything from 12 to 30 units of Novorapid. By the end of the week I was on 3-5 units of Levemir maximum with 4-6 units of Novorapid during the day and sugars almost entirely flat between 5 and 7 mmol/L (multiply that by 18 if reading this in the US).

Besides weight loss and increased insulin sensitivity, I also saw the elimination of puffiness in my left ankle. This had been going on for some time and is par for the course with long running and probably also with getting older. I think that doing something restorative for the body as a whole and in particular the lymphatic system contributed to this, and inflammation has not returned.

Kerry – possibly using another Longo analogy, talks about a steam train with engine problems struggling to make it to the next station. By ripping up the old chairs and tables and rotten window frames from various carriages and burning them alongside coal, the train can make it to its next stop where it gets fitted with fresh furnishings and can set out renewed. This is simply what the body does when directed to recycle its own failing tissues, with resultant regeneration.

I’ve had no previous experience of broken bones but after a medical registrar told me my finger would take longer to heal because of diabetes (this is also someone who did not identify themselves as a registrar, leading me to believe they were a qualified specialist until we went to book a follow-up appointment, ha! – always check on that stuff) the physio 4 weeks later would tell me that I had actually healed very quickly. Possibly a coincidence, but…

In short, the Fasting Mimicking Diet is – in my opinion, obviously – a great tool for improving health in a number of ways. There are immediate benefits that are physically observable, but also the way that I thought about food – often absentmindedly grazing or eating totally denatured junk food – changed during and after the process. It’s strange that so many people feel comfortable with what can easily amount to over-medication or radical interventions like surgery, but flinch hard at the idea of restricted calorie intake in order to kick off natural and well documented beneficial health processes.

For fatigued long runners, type 1 diabetics, and anyone not happy with the way their body is working I would definitely recommend the FMD. I’m looking forward to a second round in March and a third in May, as Hardrock 2019 draws closer.

(this is here in case you’re a type 1 or dealing with diabetes and specifically interested in how blood sugars on low insulin and almost no exercise reacted to the FMD with the insulin and food intakes described above).



5 thoughts on “Fasting Mimicking Diet, type 1 diabetes & endurance running  

  1. Really interesting – i’d want to do with basal insulin during the five days?
    ( also, I have sent you an email on messenger, but not sure if you use that? Think you should get my email address privately on here, can’t find one for you! )

  2. Very interesting, did the reduced insulin effects stay for a while after the diet and if so for how long?

    1. My insulin intake is generally relatively low because of regular exercise. Rather than noticing lowered intake under normal conditions, I notice elevated requirements during prolonged desk bound periods. Some increased sensitivity lingered, but more along the lines of only taking 8-10u Levemir per day versus 12-14u.

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