Back in the day, (I'm talking the late 90's) I first stumbled upon a dreadmill under the guidance of a gym instructor called Andy. After a short period of getting to know my new gym programme, I realised it was pretty much the same as every other members. And like the others, I noticed that the results didn't match my expectations. So, I set about my now infamous year of exercise experiment.
You may think that I have always been motivated to research and disprove things prior to engaging in them. You'd be wrong, I came from a sports background, and in the land of sports you do as everyone has done before you. Whilst riding for Team GB I ate pasta like I was advised, and drank random drinks like a good little athlete. However, when I had a crash and injured my knee (someone crashed into my car), my weight gradually crept up and my knee began to deteriorate rapidly, (at this point I was only in my early 20's) so I did what everyone else does...I joined a gym to get fit. This was the beginning of my now famous n=1 experiments.
- Repeated measures.
The randomisation came from asking a member at the gym to pull 4 sealed options out of a hat;
- Resistance Exercise
- Cardio first followed by Resistance
- Resistance first followed by cardio
The repeated measures simply came from repeating each option more than once to try and replicate the result.
Now let me make this implicitly clear, back in those days I had begun work as an Engineer at Rolls Royce. I approached this in a methodical way and not as a true scientist (although science isn’t as rigorous as it should be these days), so do not take this as gold standard research.
Despite criticism of n1 studies (such as you need a large group), I still believe to this day we all should to some degree, utilise n1 self experimentation as a strategy for individualising our own healthcare. As opposed to relying upon an authoritarian doctrine that is aimed at the masses. (1)
Admittedly I didn't record it as well as I would if I were to redo it (not a chance in hell), but at the end of the period I was 4lbs lighter overall with little difference between the options in terms of results (in fact no noticeable difference). You could conclude (as the gym instructor tried to tell me), that muscle weighs more than fat, only I wasn't more muscular. You could argue that I was a little less flabby but I was fat (my mum called me chunky).
This led to the almost famous (it may not be Paris Hilton status but its been widely discussed in some forums on the net, and I did get known as the 6000 calorie diet man for a short period) n=1 diet experiment. I’ve already blogged about this here The No Diet Diet
Marks Daily Apple
It’s pretty weird to read about yourself online (I only found the top two today whilst searching for some others that I already knew of) and when reading about the 6k calories a day experiment and some of the comments about it, it makes me really concur with Ray Peat when he talks about the importance of taking things in context. Anyway, I digress (I do a lot of that).
So, back to the exercise. I was always curious about those heart rate target zones on treadmills. The guidance on the machines basically stated that low level activity, keeping your heart rate closer to 'normal' was the fat burning zone, and as you progress further away to the higher heart rate zones, you are looking at performance benefits and not fat burning, so probably more for athletes.
Using fat, particularly in a gym was seen as the more desirable option, in fact it was the only option. The vast majority of people going to the gym are there for the specific purpose of burning fat. So why would anyone go there and want to use glucose as fuel? That there was a vending machine selling energy drinks seemed laughable, seeing as it was the antithesis of what people are in the gym to do...this was a serious business and fat was and is the fuel of choice in most commercial gyms.
However this troubled me from the very beginning, and all my studying up until that point (still relatively little compared to now) showed me that glucose was the body’s preferred fuel for anything more strenuous than rest. Lay in bed and you can use lipolysis, in which fats are broken down to release fatty acids for fuel. (Click this link for a little more detail on which tissues prefer which fuel) During a resting state, 85% of your muscles fuel needs are met by fatty acid catabolism, as you move away from resting state this percentage progressively decreases. I just couldn't understand why why everyone was (and still are) completing such punishing exercise regimes with such a fearsome intensity. Why when it was clear that fat was used as low intensity fuel, did they push themselves so hard? Even the gym machines hinted at this very fact...
To understand your body and how it works, a little better, I’m going to science for a bit, I’m attempting to keep it relatively simple, but it is a fairly complex topic, for slightly more detail please follow this cellular respiration link. Bear with me, it will be worth it as you will get to know your body better and in turn will not have to listen to the nonsense being peddled by various body coaches and personal drainers.
Glycolysis - Step One
It yields two Adenosine triphosphate (ATP).
Citric Acid Cycle - Step Two
Electron Transport Chain - Step Three
Unfortunately we live in a world where it is hipster to restrict both things in the belief that you can biohack yourself to a better body and life.As such what we commonly see in those that produce energy inefficiently via glycolysis, is an Increase in the blood levels of adrenaline, cortisol, and lactate (aka stress hormones) and issues with sugar and insulin regulation.
These are common issues that I see on a daily basis in those displaying symptoms such as diabetes, obesity, cancer, and general degeneration/ageing. These victims, I mean people, also tend to have a decreased respiratory quotient, which means they exhale less carbon dioxide on either my capnograph or my indirect calorimeter (used to measure resting metabolic rate). Measure any of these against a small child and you'll typically see that ageing and disease (along with obesity) correlates with a switch to using fats (free fatty acids to be exact) for fuel instead of glucose. You also tend to see alterations in body temp and pulse, but we've discussed that many times before and will again in the future – but just for a quick reference, body temperature and pulse tend to decline too.
What does all this translate to? Well, in the absence of oxygen (such as when you go against the clock at CrassFit, or take part in the Race for Life (an ironic name if ever there was one), you push yourself into a hypoxic state (i.e. you starve yourself of O2, effectively strangling your cells) as you pant for breath. This causes a stress state, which your body helpfully responds to with adrenaline (and later cortisol), to assist in the hunt for energy. The adrenaline liberates free fatty acids and tissue into your blood supply to use as fuel. Hurray, you've now achieved your goal, you're a fat burner. But quite probably not in the way you want to be.
This is because the utilisation of free fatty acids (fat burning) does have some major drawbacks. Firstly, less carbon dioxide is produced, and as I mentioned earlier, CO2 is a diagnostic measure of resting metabolic rate. So right away the evidence is building that breathless exercise is tanking your metabolism (because it is using fat as a fuel, rather than glucose, the same as when you do ‘low carb’). Sure we've all heard the stories that exercise boosts your metabolism, and yeah it does produce that effect temporarily, but as Dr. Peat once said, a better way to achieve that would be a warm bath. I recognise that this doesn’t make for such an interesting Facebook status but its better for you in the long run.
Another factor in this temporary increase of ‘buy now, pay later’ metaboism is the previously mentioned increased adrenaline levels which stimulates metabolism via the stress reaction. Do you want to rely on stress to keep your metabolism raised? Believe or not, some people do attempt it. Some people are living with the consequences of doing exactly – Sarah is a prime example, trashed her body with years of dieting and stress and now has an inflammatory bowel condition, more about that another time.
Anyway, back to the CO2. Without it you would really struggle to use glucose and oxygen properly. Think of middle to long distance runners and long distance cyclists, they are a group known for training at altitude, where CO2 concentrations are higher which aids recovery and performance. They're also prone to a little EPO (erythropoietin), but that is a whole different story. Dr. Brown who has been used by Nike athletes, is infamous for diagnosing sub-clinical hypothyroidism in athletes, which is is a funny coincidence seeing that you also need adequate thyroid hormone to produce CO2. (As a side note, it is always worth paying attention to the methods athletes will use to both enhance performance and protect their health, such as Maria Sharapova who was recently caught using a drug called Mildronate/Mildonium, which basically aims to help you maintain cellular respiration, something that you can do yourself if you stop participating in endurance exercise and maintain an adequate supply of energy.
The more you use fatty acids, the more you damage the cell and prevent it from being able to generate energy via the three steps mentioned above. This is again a factor in sport, as it takes time for an endurance athlete to adapt and become proficient in performing using free fatty acids rather than glucose. As such, it usually takes till 30+ before these athletes start peaking. And one of the things they train for, is to increase their lactate threshold (more on lactate/lactic acid another time).
Similarly, in the average dieter/gym user it takes a while to adapt, but given the right environment (limit sugars, limit calories, increase exercise, use unsaturated fats, increase protein intake by way of protein shakes and millions of egg whites) by the time you're an adult then you should be doing a fantastic job of slowing things down and becoming that beast that is the hangry FAT BURNER (by now, Im hoping that you are coming to the realisation that the FB (Fat Burner) promise isn’t all it is cracked up to be!)
Philip Randle, Peter Garland, Nick Hales, and Eric Newsholme proposed what became known as the Randle Cycle in 1963 (2), in which they proposed that a glucose-fatty acid cycle described the competition for fuel selection, specifically between that of glucose and fatty acids. Randle et al were able to identify that one nutrient was able to inhibit the other (3). In short they identified the biochemical mechanism by which fatty acids inhibits the use of glucose and the route which any number of Instanity, Zumba, CrossFit Wodders and numerous others wish to live their days, in an adapted state in which they assume a higher moral ground whilst living sub-standardly. That the randle cycle provides a highly plausible explanation of diabetes pathophysiology, in which energy metabolism becomes dysfunctional, makes you wonder why any Paleoer that can read would aspire to “fatty acid syndrome”. The inhibition of glucose by fatty acids blocks the cells ability to use glucose, which does look pretty damn similar to the description of diabetes, in which the ability for insulin to enable glucose uptake by muscle is inhibited.
Why though would glucose be spared by the body if it is the preferential fuel? Simple, the act of depriving the cell of glucose, such as in a fasted state (hello all you pre breakfast trainers), activates lipolysis and the inhibition of glucose oxidation provides a glucose-sparing effect that works as an essential survival mechanism for the brain during starvation. Yes thats right...fasted training means nothing more than starving yourself and having to use a survival mechanism to assist. It’s the physiological equivalent of driving on the spare wheel.
You may claim you don't get breathless (and this may well be true, but that could just mean that you’re hyperventilating at rest), and that you don't starve yourself on your high protein, high fat, low carbohydrate diet. Yet exercise and a high fat intake have been shown to inhibit glucose use. The unoxidised glucose is even rerouted to glycogen which correlates nicely with the increase of glycogen evident in the muscles of those suffering both diabetes and starvation (2).
“The antagonism between fat and sugar that Randle described can involve the suppression of sugar oxidation when the concentration of fats in the bloodstream is increased by eating fatty food, or by releasing fats from the tissues by lipolysis, but it can also involve the suppression of fat oxidation by inhibiting the release of fatty acids from the tissues, when a sufficient amount of sugar is eaten.” ~ Dr. Ray Peat
Woah whoa whoa, so you mean to tell me that there is a way of halting this cell damage by simply eating glucose? (4), and it’s never too late to abandon the "lifestyle" and return to so called "dirty eating" aka being functionally nourished and happy?
The inhibition of lipolysis freaks people out, we have been conditioned to believe that we need to burn fats, by people who are making a living out of not understanding basic biology. It never made sense to me to force our bodies into any state. From my initial days of study as a PT, restoration of metabolism always seemed logical and safe. Would you force a baby to eat fried bacon and bulletproof coffee, with a side of boiled egg whites, to put it into a fatty acid state? I certainly hope not.
We can never use just one fuel, some tissues will prefer fats and some glucose. And so the best thing to do is to give the body a mix of both and then it has everything available at its disposal. Simples.
2. Randle PJ, Garland PB, Hales CN, & Newsholme EA. The glucose fatty-acid cycle. Its role in insulin sensitivity and the metabolic disturbances of diabetes mellitus. Lancet 1: 785–789, 1963.
3. Randle PJ, Newsholme EA, Garland PB. Regulation of glucose uptake by muscle. 8. Effects of fatty acids, ketone bodies and pyruvate, and of alloxan-diabetes and starvation, on the uptake and metabolic fate of glucose in rat heart and diaphragm muscles. Biochem J 93: 652–665, 1964.
4. Taegtmeyer H, Hems R, Krebs HA. Utilization of energy providing substrates in the isolated working rat heart. Biochem J 186: 701–711, 1980.