Why fitness is medicine, and you should learn about Fasting Mimicking Exercise (FME)

Dr Richard Babor, a cancer surgeon, and his new TV show “How not to get cancer” attracted loads of attention. There was some negative reaction because people felt they were being unfairly blamed for getting cancer, because poor lifestyle was pinned as a major cause of cancer. I doubt that was the intention of the show. In fact, Dr Babor clearly started in the intro that “it’s no one’s fault personally” and this is an important point.

Screenshot 2019-07-17 12.03.36

But it is a big public health issue. No one wants cancer, and we want to know if we can prevent it.

The way public health researchers have assessed the situation is to look at cohorts who behave in certain ways and those who do things differently. What we have seen is that things like smoking, poor diet, low fitness and activity, poor sleep and other lifestyle factors account for quite big differences. Maybe half of all cancers could be prevented by healthy lifestyle.

That’s not a personal fault of anyone. But it is a big societal issue. I’m assuming we all want along and healthy life.

We’ve grabbed smoking by the horns over the last few decades. Drinking is improving in some groups. Food guidelines and the food environment have been hijacked by the processed food industry. Fitness continues to plummet, especially in our kids.

This post is about fitness.

It’s about how some of the finer details which can make a big difference.

It includes the extra information that didn’t fit into the few minutes of my appearance on Dr Babor’s show. I’ve been asked a lot to write about this and provide some detail and “how to” of what he did and how he massively helped his fitness by slowing down, doing a little less (but still plenty) and boosting the physiology of the anti-cancer environment.

It’s about the finer details that are important for our long-term health and happiness. I’m assign there are a lot of people who want the best actable information about lifestyle and health, not the “minimum guidelines for couch potatoes”.

Fitness is medicine. So here goes….

The features of the pro- and anti-cancer internal environment

One way of thinking about human physiology around growth and repair cycles is to understand the catabolic versus anabolic states. In catabolism your body is repairing and tidying up what it has – it’s a non-growth, use-what-you-have state. In anabolism, you are growing more – cells divide – you grow, you store.

One view is that most modern humans end up spending far too much time in the anabolic (growth and storage) state, and not much time in the catabolic (repair and use) state. Because the anabolic state is one of inflammation – that’s what stimulates the process, then this chronic inflammation is never stopped and this is the root cause of modern chronic disease – cancer, heart disease and stroke, Alzheimer’s disease and dementia, and diabetes.

One way the catabolic environment might deal with early cancer cells is that they (early cancer cells) are metabolically disadvantaged in this state. Cancer cells themselves are unable to become catabolic.  Early cancer and pre-cancer cells may be more likely to be recycled through autophagnic and apoptotic processes. The anabolic state is pro-cancer because it is a growth-promoting environment – exactly what early cancer cells want. The inflammation and reactive oxygen species might create further mutations to more aggressive cancer type cells.

There’s some speculation above, but I think the evidence points the fact that we could do with getting into the catabolic state from time to time. Regularly even.

The features of a catabolic state (cell repair, use of whats left, stimulated by nutrient stress)

  1. Low insulin and glucose
  2. Low IGF-1 (insulin-like growth factor)
  3. Anti-inflammatory
  4. Low reactive oxygen species
  5. Ketogenic signalling
  6. High immune functioning
  7. Autophagy

The features of an anabolic state (cell growth, storage, stimulated by food and stress)

  1. Inflammation
  2. High reactive oxygen species
  3. High IGF-1

To be clear both states are essential for fully functioning healthy humans. But you do need to be able to access both.

What we need to get catabolic signalling going is nutrient stress. That is, not enough nutrients. This forces the body to stop the growth and scavenge through a process called autophagy (literally self eating) where every cell in the body uses the lysosome to recycle and find old organelles and scraps floating around inter- and even extra-cellularly.

It’s a process essential for optimal function, including probably the early destruction of cancer and pre-cancerous cells (see above).

Fasting (i.e. not eating) is the most obvious way of stimulating catabolism. Getting insulin higher (eating carbohydrate and protein) is the path to anabolism.

Fasting and fasting mimicking

Here are the known ways to get that catabolic environment.  It turns out you can get the same (or similar) effects to fasting while still eating as well!

  1. Extended fasting. That’s right – not eating for a few days gets you right there. I’ve done this several times and you feel great. But it does have some drawbacks…Pros:  Save money, get ketogenic signalling going quickly. Cons:  You are not eating, people classify you as “that person”, and you may lose muscle mass and reduce your metabolic rate.
  2. Intermittent fasting. Not eating for longish periods during a day e.g. miss breakfast and lunch. I’ve done lots of this and wrote a book (What the Fast?) all about this. I find it a practical way to cycle in handout of the catabolic state. Pros: Pretty simple, save money, you have more time during the day to do other things. Cons: Still requires will power.
  3. A fasting mimicking diet (keto). I written even more about this in all the What the Fat? books. I like low carb as a base for living. Pros: It’s yummy, you feel full, you get the nutrients you need. Cons: It can be costly, takes preparation, and sometimes you feel a little limited in the pathological food world we live in.
  4. Fasting mimicking Exercise (FME). I’ve written almost nothing about this and it’s about time I did, because exercise training on a healthy diet where the intensity is low (at or below aerobic threshold) has a profoundly useful signalling effect on the body – it stimulates low glucose, insulin, IGF-1, increased ketones, and all the rest of the catabolic pathway. That’s why I’m calling it FME. Pros: It’s free, it’s fun, it’s super easy (the effort level is ridiculously and counterintuitively low), and you get the benefits like increased cardiorespiratory fitness (see below), relief of arthritis and back pain, better mood and mental health, and increase muscle mass and your metabolic rate. Cons: You have to do it, but even when you don’t feel like doing it, you return feeling like it was worth it.

So there is your quiver of catabolic tools. Most of you would have heard of the first three. Here’s to adding the fourth, FME!

Oh, but wait there’s more. Being fit is good for you for lots of reasons. Here’s some epidemiology.

Why fitness is medicine

Screenshot 2019-07-17 12.11.42

It’s long been known that high fitness is associated with better health – living longer and with less disability. But there has always been a thought in public health that we may as well just tell the half of us who hardly move at all (or don’t meet the minimum physical activity guidelines) that any movement is good movement, and that 30 min of anything 5 days a week is enough.

True, it’s enough for the minimum benefit. You are way better off doing something than nothing. So if that’s you, read no further and go outside and get started.

There has also been a school of thought that we have people in society who take their fitness way too seriously. We even give them names like “fitness freak”. (I’ve been called that…)

I submit to you that there are many in society who want to have the full information about what constitutes optimal health and best possible outcomes. This is what this post is about in regards to fitness.

I guess the idea that you can wreak havoc by overdoing it is real. I have over-trained, and achieved less than optimal fitness by being an idiot about it. Hopefully I can show  you the best way to not get into this space.

What recent studies have shown us is that there is no such thing as “too fit”. The fitter you are the better you do on pretty much everything.

Here are a couple of studies to show you this.

First, this study in the Journal of American College of Cardiology shows a linear dose-response between fitness and all cause death, cancer death, and cardiovascular death. The least fit are twice as like to get all of these.

An important feature is the continuous dose-response relationship.

Screenshot 2019-07-17 12.10.58

In the paper “Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing” they followed more than 122 000 people for more than 8 years. what was cool here was that they had enough people in the study to look at the very fit ones. The top few percent they called “elite fit” older adults.

Screenshot 2019-07-18 14.51.19

Here’s what they found:

Results  The study population included 122 007 patients (mean [SD] age, 53.4 [12.6] years; 72 173 [59.2%] male). Death occurred in 13 637 patients during 1.1 million person-years of observation. Risk-adjusted all-cause mortality was inversely proportional to cardiorespiratory fitness and was lowest in elite performers (elite vs low: adjusted hazard ratio [HR], 0.20; 95% CI, 0.16-0.24; P < .001; elite vs high: adjusted HR, 0.77; 95% CI, 0.63-0.95; P = .02). The increase in all-cause mortality associated with reduced cardiorespiratory fitness (low vs elite: adjusted HR, 5.04; 95% CI, 4.10-6.20; P < .001; below average vs above average: adjusted HR, 1.41; 95% CI, 1.34-1.49; P < .001) was comparable to or greater than traditional clinical risk factors (coronary artery disease: adjusted HR, 1.29; 95% CI, 1.24-1.35; P < .001; smoking: adjusted HR, 1.41; 95% CI, 1.36-1.46; P < .001; diabetes: adjusted HR, 1.40; 95% CI, 1.34-1.46; P < .001). In subgroup analysis, the benefit of elite over high performance was present in patients 70 years or older (adjusted HR, 0.71; 95% CI, 0.52-0.98; P = .04) and patients with hypertension (adjusted HR, 0.70; 95% CI, 0.50-0.99; P = .05). Extreme cardiorespiratory fitness (≥2 SDs above the mean for age and sex) was associated with the lowest risk-adjusted all-cause mortality compared with all other performance groups.

In actual plain English this means that

  1. The fitter you were the better
  2. The elite fit had 5 X less chance of dying than the least fit people.
  3. This effect is akin to the effects of smoking
  4. There is still a large effect even from moving from the high fit to the elite fit group

Yes it’s a prospective study. There may be confounders, but it’s unlikely with the effect sizes this large and the known biology involved. In my opinion, the totality of the evidence easily meets Sir Austin Bradford-Hill’s criteria for causal inference.

Why exercise works – exercise physiology

Just as an important note, I think we should do a bit of exercise physiology. First is the concept of Hormesis. Hormesis is the theory that sub-toxic stress is good if we can adapt to it. We end up adjusting our biology to cope with that stress.

We rebuild bigger faster, stronger, more resilient to that stress.

Lose dose radiation is good for us, the toxins in plants may be good for us, cycling between heat and cold stresses in a sauna is good for us, and exercise if we adapt is a stress which can produce a resilient,. stronger system, What doesn’t kill us makes us stronger right?

All good so far. But I think we should be thinking about exercise in two separate stressful modes. They are stressful for completely different reasons.

The first I’ll call anabolic exercise. It’s short and high intensity. You burn glucose and you damage the cells in the body. They respond. This is why weight training, HIT (high intensity interval) training are important and useful. It’s also why you shouldn’t over do this, and should periodise your exercise and allow recovery between hard efforts.  It’s my view that many exercisers do too much anabolic exercise and do not allow enough recovery. The damage you create is inflammatory and acutely is good for you. Chronically it’s bad. This is what leads to burnout, sickness, and injury.

What we hardly talk about is catabolic exercise. It’s typically very easy aerobic exercise that creates stress through nutrient stress pathways. That’s why I call it Fasting Mimicking Exercise. It reduces glucose, insulin, IGF-1, inflammation, improves immune function, and generates ketogenic signalling pathways.

Both types of exercise are stressful. Both have hormetic effects. Both are useful.

If you want to exercise catabolically, then you need to know about the Maximum Aerobic Function or MAF.

Introducing MAF

MAF is where you move from exclusive use of the aerobic energy system to include the increasing use of the anaerobic system. Exercise below this level is easy, feels easy – even if you are unfit – you will just go slower the less fit you are.  in practical terms it’s where you have any hint of puffing at all. It’s a pace you could carry on with indefinitely.  It’s my view that most exercisers don’t go easy enough to achieve this level.

MAF shouldn’t confused with the anaerobic threshold which is what you sustain in a very hard 30-60 min of intense exercise and above this you can’t speak at all. We are not aiming for this level of hard. In fact, most of us should avoid this except for the occasional high intensity interval training. Its my view that this is where most people exercise when they exercise. No wonder they are tired and find motivation an issue.

I first heard about MAF from Mark Allen (6 time Hawaii Ironman winner) in 1995 at a pro race briefing at the Hawaii Ironman triathlon world championships. I was also a pro athlete there and thought that I may as well ask him what he did to be so awesome.

He was surprisingly forthcoming. He told me about the methods of his coach Dr Phil Maffetone. Allen trained with a heart rate monitor. He did most of his work at or under his MAF threshold. The MAF heart rate is simply:

MAF heart rate = 180 – age

  • Add 5-10 beats for high lifetime fitness and being fit
  • Subtract 5-10 for sickness, low fitness

Exampleme (Grant, aged 50) = 180-50 = 130 add 10 beats for lifetime experience and high fitness = 140

Example (38 year old female, not very fit) = 180-38 = 142  low fitness = 138

Allen explained that this give him all the fat burning and fitness benefits he needed to be the old champion without all the inflammation and burnout, injuries and tiredness others got. He further explained that Dr Maffetone insisted he maintain a low carb high fat diet to further the process, because high carb, sugar diets made it harder to get the catabolic fat burning benefits from the MAF training.

That was interesting, and completely contrary to what I (a trained scientist) knew about exercise training and nutrition. Remember, I was in the land of Gatorade and threshold training.

So I flipped off his advice as lies and propaganda and keep drinking Gatorade and eating pasta and trained as hard as I could. I got inflamed, sick and fat. Allen went on to win another title!

It was another 17 years before I came to understanding the genius of Maffetone. He was miles ahead of us. Decades later!

Read more about Dr Phil Maffetone here 


Dr Phil Maffetone – a pioneer on catabolic exercise

The MAF test

Now comes the key to this, and what I did with Dr Babor among others. Monitoring your fitness progress using the MAF test is a critical factor in understanding if your exercise is working the way it should. If you exercise and you aren’t getting fitter then what are you doing?

You can read much more on Dr Maffetone’s MAF test on www site here

Maffetone has you walk, jog, or run (depending on your fitness) at your MAF heart rate for 5 miles measuring the time it takes to do each mile. It’s super easy because you are at such a low heat rate, so the test itself hardly feels like a test.

Here are the improvements in MAF test results of a marathon runner over several months. It’s impressive stuff.


Improvements in MAF mile times for a marathon runner using MAF training principles and the MAF test

The test monitors your progress. The MAF pace training improves you without the stress and risk of hard exercise.

OK, well we are not all marathon runners so let’s move down some levels. First here’s me over a two-month period doing a Thursday run. I opted not to do the 5 X 1 mile test, but just went to a hour or so run-walk on the same circuit. I had a break between lectures on Thursday so went out to get some space. The run was up and down hills and off road in places. I had to walk almost all of the hills to stay under 140 HR.

You will see I improved using MAF training by an incredible 11 min over two months. In other words, I ran the same circuit with the same heart rate 15 percent faster just doing easy jogging and walking. This translates into faster paced running too. I cracked out a 1.25 hr half marathon just doing this. I had been trying prior to this, and too hard. I was only able to run a 1.34 half marathon despite harder training before this.

Weekly run (hilly bush loop form AUT Akoranga campus around Tuff’sCarter and through Kauri Glen bush) Run time

@ <140 BPM

1st March 72 min
8th March 69 min
18thMarch 66 min
22ndMarch 64 min
29thMarch 63 min
6th April 62 min
13th April 64 min
20th April 62 min
27th April 61 min

Dr Babor

In the “How not to get cancer” show I prescribed Dr Babor a MAF exercise program based on fasting mimicking excess principles. I adapted Phil Maffetone’s “MAF” test but used kilometres. It takes less time and yields just as much information. And In my part of the world, who knows what a mile is anyway. A km is way easier to figure out, and it’s how we measure pace when we run/walk

His results astonished even me. In test one on the running track outside my office here at AUT Millennium he managed about 8.30 min per km. That’s pretty pedestrian.

This surprised me because he was going for 90 min hard runs and feel quite tired for his exercise.

Over the next four months he did a similar or slightly less volume, and kept his heart rate under his MAF threshold. He used a heart rate monitor to do so. This meant walking up lots of hills.

Look at the improvement (some due to learning to do the test better perhaps) but he was running 3 min/km faster for the exact same heart rate!

All this by slowing down, and getting catabolic.

As Mark Allen told me. I think this works better when augmented with a low carb diet. That’s the ultimate fasting mimicking, catabolic way to live and therefore the “anti-cancer” combination Dr Babor was looking for in his show.

Kilometre Test 1 July 8th

@ <134 BPM

Test 2 Oct 23rd

@ <134 BPM

1 8.19 5.05
2 8.35 5.24
3 8.53 5.39
4 8.48 5.42
5 8.42 5.49

Matt Kerr: High performance

I wanted to finish with an actual high performance example. This is Matt Kerr, whom I coach. He’s an elite triathlete. He’s lean, he’s fit, he’s fast.

But he was training too hard, and eating too may carbs in my opinion.

We tested him on our more advanced equipment at our Human Performance labsat AUT Millennium. You get a lot of information about fat burning, catabolic and anabolic exercise, and pace with this sort of testing.


Matt Kerr doing testing in Human Performance labs with us at AUT Millennium

Here’s Matt’s metabolic flexibility curve at high carb, high intensity training at baseline. Remember he is extremely fit. He’s just come off some good shorter racing. But he’s a carb burner. He hardly ever burns fat, and doesn’t do that very well.

Although fit, he had a series of winter injuries I think related to poor training and diet.

He was maxing out at  0.52 g/min of fat burning and doing so at 135 w of power on the bike. That’s slow. That means he relies on carb burning. It means that almost all of the 20 hours training a week he does creates an inflammatory, low immune function, high ROS environment. That’s a recipe for sickness, injury and poor performance especially in long races.

Screenshot 2019-07-19 10.37.31

Matt he carb burner. MAF training with this profile is les effective because you burn sugar at low intensity

I threw Matt onto a keto diet, MAF train for almost all of his sessions, and included some fasted long rides at a very easy pace.


Screenshot 2019-07-19 10.37.21

Test 2 – a marked increase in Matt’s fat burning (new solid red line) at a given power on the bike. He turned from a carb burner to a fat burner – which makes his MAF training even more FME

He could now oxidise 1.1 g/min of fat and could do so at 240 W on the bike. That’s fast and it means training and racing is a clean burning low inflammation, low ROS, high immune function environment

He ended up placing in the top 10 at Ironman NZ in his first race over that distance, in 9 hr 18 min.

OK, this won’t mean much to most of you. For those in that game, its an incredible result. The results for myself, Dr Babor, and Matt show that the same principles apply across all sorts of individuals. I’ve used this with young and old, fast and slow with the same results.

You see, we are all human and we will respond to the stress of catabolic FME. You can’t fail with this if executed properly.

Tools you will need

(disclosures – I have no association with any of these products or companies other than I have bought them and use them myself)

There is just no way around this. If you want to do this method you need an objective measure of effort and heart rate is the easiest. You will need a heart rate monitor of some sort. My preference is an actual smart watch with wrist-based HR. Here’s my Garmin 235 which is the cheaper, but still expensive….

Well there is a way around it. If you can’t afford a heart-rate monitor, just measure the rate by taking your pulse with a watch after different types of exercise to get some idea where your MAF range lies. Believe me its hard to get that really to the level of accuracy you need, but possible I guess.

My watch downloads to a smart app. It’s fun and easy to use.


My trusty Garmin Forerunner 235

You can also connect to Strava – a sort of social media for fitness. Its really fun. I have all my friends and family on it. OK, not for everyone but it is cool. Your friends can give you “kudos” which sounds corny but is great.

I also bike lots, swim and surf a bit, and walk a lot. All of these pop up on my smart watch and Strava. Here’s yesterday’s bike in the trainer (I use Zwift, a game type program which is also heaps of fun – you can see my setup in the video at the end of this post).

OK you don’t need to have all the tech stuff I do. But I do love this stuff and it’s a great investment, if you can afford it, in your health and well-being.

How much money do we spend on sickness in our society?

We should dish this stuff out at the doctor. Imagine you go to the doctor and come back with a Garmin 235, a bike, a smart trainer and a Strava account!!

Probably we would save the country money and improve our lot as a society?

Screenshot 2019-07-17 16.54.32

My Strava output after a Zwift session

Practicalities and final words

Society needs a new perspective on fitness. We need to take it regularly, seriously, but not too hard.

Let’s give up on the term, fitness freak!

If you are going to go this way then get others involved otherwise you’ll be so slow they’ll leave you behind while they all rush off into inflammatory, anabolic exercise land. You have to get your head around the fact that this is slow and easy, and that counterintuitively you get the real benefit by slowing down.

You want the whole peak performance – to be the best you can be – so yes, do the weights and high intensity as well, but not too much.

How much volume is too much? That totally depends on where you are starting from. But very fit humans can easily manage a few hours (or more) of MAF./FME a day. You don’t have to do that unless you are in training for an Ironman triathlon or similar. So start with what feels easy and take it from there. Just keep the heart rate down. Walk when you need to, and leave your ego in a brown paper bag on the kitchen bench before you go out the door. You can collect it when you get back.

I’ll leave you with my short video on “fitness is medicine” (watch out for Bluey, my border collie who is the main star) – enjoy and see you out there (going slowly!)



7 Comments on “Why fitness is medicine, and you should learn about Fasting Mimicking Exercise (FME)

  1. I am a 78 year old female and have been interested in natural health for most of my life. However would appreciate any suggestions you may have so that I can maintain a healthy life. I do not use any prescription drugs. Many thanks, June

  2. Thank you for this well-composed, useful and enjoyable article!

  3. Yea – nice one Grant, I enjoyed that. Especially your video.
    It appears that the MAF heart rate equates to about zone 2 (endurance training) that is often spoken about in bike riding circles.
    I wonder if we can modify the MAF test for an indoor bike trainer (or treadmill for that matter).
    Especially now that we in NZ are into winter.
    What do you think?

  4. I was quite amazed to read this and suddenly understood what I had been doing wrong and right during the last 40 years!
    I could never train hard for long distance running. I would always get a “stitch”. I then discovered that if I went slowly enough, I could go on for hours. By doing the slow, long jogs, I got better and better until one day I accidentally discovered my Resting Heart Rate was down to 55. That was 20 years ago. I will get back to MAF training now, since I understand exactly what it is. Now 74 years old on LCHF diet, since I was diagnosed with T2DM in 2015, now “in remission” I think with Hba1c of 5.4%. I have your book(s). Great stuff! Thank you! Keep it up!

  5. In the study cited, the only question I have is the use of “hazard ratio”. This appears to be similar as relative risk, right? Which tends to exaggerate effects of different variables; from years reading epidemiological nutritional studies, my antennae twitch when I see the words “relative risk”. This didn’t help a whole lot: https://www.quora.com/How-do-you-explain-the-difference-between-hazard-ratio-and-relative-risk-to-a-layman

    Otherwise, it’s a wonderful article and has inspired me to order a heart rate monitor. I’ve been low-carb for about 10 years, but a few months ago got a breast cancer diagnosis so I’m trying to clean up my act in terms of exercise and more-strict keto. As it is I only eat one meal a day.

Leave a Reply to totaram Cancel reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: