Spoiler alert: You don’t need to drink bulletproof coffee, you don’t need to shovel carbs down your throat and you don’t need to “convert” to ketogenesis.

The key to maximizing endurance performance, or performance in general, is getting the required adaptations from ALL sessions, you could be shooting yourself in the foot, unwittingly, read on to find out more.

This is a topic that gets hotly debated by many, mostly people on polar opposite ends of the spectrum in terms of high fat and high carb advocates, with both side putting forward their centerpiece argument, be it mitochondrial biogenesis or mTOR pathway activation. Both sides are correct, but it is important to note that both sides are equally as dogmatic and pedantic as they are correct, in technical terms, and nobody wins. Once again, the answer lies in the murky grey area as to how to use carbs & fats in your sporting or fitness endeavors to get the absolute most out of it. In summary, the low carb approach can be looked at almost in the same light as ergogenic aid (a supplement), there are certain sessions where it is beneficial, it has drawbacks if over utilized and it is not magic in isolation, also the results are less likely to benefit increasingly elite athletes.

So why can’t we go low carb for all the time? You can, if your training regime consists solely of easy aerobic work, you don’t train everyday and your not really buzzed about your performance, as your recovery will be impeded, thus your progression will be. If you have no tough sessions, nothing with a hint of intensity, no actual performance goals, and you don’t mind feeling sluggish, then go bananas (or avocados, rather), do all the fasted cardio you can manage, but just consume your carbs after training, don’t hold out on glycogen repletion. If you have an actual race season, some performance goals and you work all elements of your aerobic and anaerobic system (any reps, hill sprints, intervals, weights, threshold work etc.) then you cannot* do those workouts off of no or low carbs. *Technically you can, BUT your rate of perceived exertion will be much higher, your oxygen cost for a given intensity will be much higher and you won’t be able to actually go near the high end of your aerobic capacity, your exercise tolerance will also drop a bit. With increasing intensity, less blood flow gets to your adipose tissue, meaning less fats are metabolized (lipolysis rates go down when intensity rises), when the PH of your muscle drops as a by product of acid formation, transporters involved in getting long chain fatty acids into mitochondria are inhibited, also in part due to a depletion in free carnitine, which acts to buffer excess Acetyl Co-A produced, to allow for maintained intensity (Acetyl Co-A accumulation down regulates how your body makes more fuel available for work). These things all result in you feeling like your parents stuck a limiter after 4th gear in your car. If you want to get the most out of the tough work your doing, if you need to power up a hill or indeed you have a race (which has short bursts of sprints, climbs etc. which often dictate race placings), that isn’t the time for low carb. I hope that makes sense, in essence, if your workout is hard, or intense, only carbohydrates can match the rate of feul burning needed, and won’t be inhibited by the by-products of high intense exercise.

Also bear in mind, for those of you reading this, who are shaking their heads, tutting and repeating over & over that “I am an endurance athlete, I ONLY use fats, because the intensity is LOW”, to you guys/gals, I say, you couldn’t be more incorrect. Fat oxidation is optimized between 45-65% of your VO2max, easy running or jogging would be just about over that range, so unless you plan on strolling race day, or your Sunday long runs are actually strolls, you are using carbs also. Now, it is a sliding scale, and it is still possible to train low carb, I’m just making a point, that carbohydrate metabolism is ALWAYS involved, from low to high end of range. Elite marathon runners will belt around 26.2 miles at 85-90% VO2max, non-elites wont get quite that high, but not from it, you guys are simply slower at running, the intensity may not differ though, triathlon would be similar, there is a case for Iron-man being an exception (which I disagree with, but that’s another blog entirely). So even for longer “slower” events, this still applies.

So when CAN we use the low carb approach, and how do we do it? Great question, let’s take a look. If you are in off season, which is winter for cyclists and most runners, then this is the time to do it, reason being is that you have no races upcoming (no important ones), and the majority of your training is easier in terms of intensity, so recovery has a little more wiggle room at this time of year. Carb fasted sessions take a bit longer to recover from in terms of glycogen depletion and repletion, which in turn can suppress your immune function, and can make subsequent bouts of exercise feel more difficult or be poorly executed. For these reasons, it is silly do it in race season, or in a block of high intensity, where recovery and session performance are PARAMOUNT to adaptations and athlete confidence. So keep it for easy weeks, off season & cross-training. Pick which sessions to try fasted or low carb based off of the following criteria:

1) How long is the session, if its <100 mins, go for it. You have enough body glycogen at low intensity exercise to last approx 100 mins, I wouldn’t push it past that. If your run is longer, take a gel at THIS point and complete the rest of your session.

2) If it’s ONLY easy cardio, go for it. If your questioning this, read the article again.

3) Can it be done first thing in the morning, or after breakfast, if so, do it. It’s okay to train fasted, or to have one meal as a low carb meal (or low GI – you more so don’t want any insulin response for “low carb” training). I don’t think it’s a good idea to opt for low carb protocols for a whole day, as it tends to be restrictive and you cut out many staple foods, risking the overall health composition of your daily diet (remember, I’m a dietitian… health first!!)

If you satisfy all the above criteria, go mad, and enjoy it. Low fat sessions can improve your ability to efficiently oxidize fats, and it can cause elevations in circulating PGC-1a, an enzyme that leads to mitochondrial biogenesis, basically the powerhouse units of your cells get bigger and more in number, meaning you can tack on points to your aerobic capacity.

For more information, or advice regarding how you can optimize your training around your life, goals and needs, get in touch. I specialize in endurance athletes and am confident that if you haven’t already addressed this topic, that nutrition can add dividends to your sporting performance. Get in touch via the website or email me at:

Thanks for reading,


Practical application series


            Supplements and ergogenic aids are all the rage at present, and represent a multi-billion-dollar industry that sits on a house of cards and is fuelled by one thing; hope. When we reach for a supplement, what we are looking for is a better outcome, an improvement, a shortcut to a desired endpoint, for some, they believe it is the only answer to a problem. This paradigm partly arises due to the fact that the supplement industry is not heavily regulated, in terms of amounts of active ingredients, and in terms of the strength of the evidence used to support a “scientific claim”, and how misleading that term can actually be. However, there are a list of evidence based and supported supplements, that do have merit in certain circumstances, let’s discuss!


            First, to clear up, there is a difference between a medically contextual application, and a general health/sporting application, sometimes there isn’t a distinction drawn between those two lines, and as someone who works on both sides of this fence, it bothers me. Let’s take for example BCAA’s, branched chain amino acids, and how they are widely promoted for their anabolic potential and supporting muscle growth. BCAA’s are metabolized in muscle, but muscle protein synthesis doesn’t occur unless ALL 20 amino acids, adequate calorie intake and anabolic signalling are in place, BCAA’s only consist of approximately 3 of 20 amino acids. BCAA’s are also found in higher concentrations in actual foods, such as meat/poultry, than in actual serving dosages of BCAA’s themselves! IN the sporting context, it doesn’t make sense to take them in the first place during exercise, as muscle protein is the last thing you will metabolize during a workout, as long as you have adequate calorie intake, overall protein intake and fuel appropriately, they are irrelevant in the equation. Now, in medical contexts, BCAA’s can be used very effectively in patients with liver failure, or cirrhosis, who have compromised ability to metabolize protein, thus supplementing intakes, they can also be used as an adjunct to aid in prevention of sarcopenia in conjunction with proper diet & exercise. Note that these scenarios do NOT apply to most people.

            Also, to note, study methods are vital to know, a study method that focuses on one cellular pathway, or metabolic interaction, may miss the point, as above, the example of BCAA’s increasing anabolic signalling, is misleading, as a rise in mTOR or insulin does not mean muscle protein synthesis, as discussed above. Signalling does not equate to physiological effect. Some studies also don’t report how they control for diet, or calorie intake, which means the results are always open to scrutiny. For example, if you took the time to read about a supplement that purported to increase performance and decrease muscle loss, you may find that the control group, were starved overnight, and the study group are given a supplement, as a lecturer once told me, if you had a control group that were starved or fasted, and a study group that licked a lollipop, there would be a difference! Sometimes, results don’t actually mean anything.


            There are 5 main evidence based supported ergogenic aids, which we will cover, along with some sports foods and nutritional products, and we will look at the context in which they are appropriate. Caffeine, creatine, nitrate/beetroot juice, Beta-alanine and bicarbonate are the supplements we will evaluate, and we will look at whey, carb powders/gels and iron supplements in addition.


            Caffeine works as an ADP receptor agonist, it doesn’t give you energy per se, it simply stops you from feeling more tired. Depending on the dosage, it can also cause central nervous system excitement and raise cortisol levels. Caffeine has mixed effects on people, due in part to built up tolerance and to genetic variants of gene CYP1A2, which dictates how it is metabolized in the liver. Caffeine doses of 3-6mg/kg confer performance benefits when consumed 60 mins prior to exercise, however opting for the lower dose of 3mg per kg wills still offer ergogenic benefit, and will decrease the likelihood of gastric distress the higher dosage can lead to. Increasing the dosage of caffeine past 9mg/kg does not continue to offer increasing benefit, due to the varied responses to caffeine, and tolerance variation, it is worth trialling out for yourself your race tactics, in training, so as to avoid any unexpected stomach issues, anxiousness or sleeping issues. Don’t worry if you’re a habitual coffee addict, your general caffeine intake will not impede the effect of the lower dosage. Evidence states that caffeine can be beneficial with the aforementioned doses if taken in a 2.5hr period prior to exercise or during, towards the latter end of the race. Caffeine doesn’t give you more energy, as some would say, it simply stops you feeling more tired, and makes you more alert, stokes the nervous system making it easier co-ordinate hard efforts, however, the psychological phenomenon is just as valid as a physiological change, in terms of aiding performance. For reference, a standard coffee had approx. 80mg of caffeine, and a gel would have anywhere from 30-80mg.


            Creatine has stood the test of time, and the hype is real. Creatine helps the body resynthesize phosphocreatine at a high rate, and also increases phosphocreatine stores. which is useful for any sport or training sessions involving explosive effort and maximal outputs. For explosive work, or anything max effort up to 6 seconds, you use your ATP-PC system, however this naturally runs out very rapidly, creatine helps replenish this, ultimately allowing one to do higher volumes of maximal and intense work, which is what leads to the strength and performance gains. Creatine has its best effects in efforts lasting under 30 seconds, it doesn’t necessarily make sense for an endurance athlete to load up on creatine, as gaining a lot of lean muscle may affect power to weight ratios, VO2 max ratio, in which case, the weight gain may neutralize any strength gains. However, early season or off season, when in general prep phase, creatine may be good to take with gym sessions, long term creatine use may avoid the weight gain noted with loading protocols, and can alter cell signalling to promote glycogen storage in cells, which may benefit the ultra-endurance athlete. Bog standard creatine monohydrate is king, no need to get fancy with it, increasing price doesn’t increase effectivity. Opt for lower doses of 2-5g per day long term as opposed to the 20g per day loading phase doses recommended for power athletes, increase your water intake, if you want to take creatine. I would recommend optimizing protein intakes, training to your max, optimize fuelling in sessions, and then, if you need extra, as an endurance athlete, to go to creatine.


                Beetroot juice has gotten a lot of press as a superpower in the media, and whilst that claim is likely to be quite an overestimation, there may be some efficacy to it, let’s take a look. Nitrates are the components in beetroot juice that offer up the benefits. Nitrates work by increasing vasodilation and oxygen uptake, which also happens naturally when you exercise. The jury is out due to mixed results and insufficient data. Some evidence dictates that intakes of nitrates offer benefits in the 2-3-hour periods post consumption, with bolus intakes of 310-560mg investigated. Elite athletes or anyone in good nick, who has a VO2 of over 60ml/kg/min, may not experience much benefit, as there is already little room for improvement, and some researchers warn that the side effects such as upset stomach may outweigh the potential gains when risks are weighed up too. This would be one to try in training, and would not be the first line of action for increasing sports performance.


                This supplement may not be too familiar for endurance athlete populations, but will be for gym goers most likely, and is known widely for its ability to give you a tingling sensation in your face, also known as skin paraesthesia. Taking beta-alanine increases muscle cell (myocytes) carnosine content, which has buffering and anti-oxidant properties, and has been shown to increase maximal exercise tolerance. There are positive intake and performance correlations across training level and elite status athletes, though the correlation is markedly weaker in increasingly elite performers. Doses of 3.2-6.4g/day split into equal doses every 3-4 hours for 4-12-week periods show efficacy, however, this is likely not realistic and does not mimic what typical consumers can or would be willing to do, making it a supplement that is likely difficult to adhere to. Some research also showed huge intra-individual differences in cell content of beta-alanine during dosage periods, as beta-alanine stays elevated for long periods of time in the body, meaning supplementing needs to be individualized and that likely more data is needed.


                This has been shown to slightly increase performance in short, high intensity events, translating to 2% improvements for events lasting less than 60 seconds. Sodium bicarb. Has similar properties to beta-alanine, but has an acute spike between 75-180 mins post consumption, meaning it would need to be trialled out repeatedly to figure optimal timing with doses of 0.2-0.4mg/kg. Also, unlike beta-alanine, this product buffers extracellularly, i.e., in the blood stream, as opposed to inside the cells. Sodium bicarb. Is very likely to lead to stomach upset and vomiting, and consuming 3-4 smaller doses per day for 3-4 days prior to the event can have the same effect, without the side effects. If that is not possible, two split doses in a 4-hour period pre-race taken with carbs, will help ease gastric suffering.


            The rest I have yet to mention are in my opinion, cupboard staples. As an endurance athlete, or active person in general, your intake needs for protein are just higher, to the tune of at least 1.2g/kg per day, which is not always easy to eat. Whey protein simply makes it easy to do, and for people getting all up in arms, higher protein intakes do not cause kidney failure, or damage your liver. If you are healthy, and have no pre-existing conditions, high protein intake is fine, and whey powder is simply dried milk. Casein is a good option prior to bed, as it is slow release, and may improve your sleep quality a tad. If you are in a power sport, injured or in a heavy training block, protein needs re higher again. Making it easy means it’s practical, means you’ll do it for longer.  

            Carb powders and gels are almost ergogenic aids, we’ve just known about them for so long. If you plan to perform maximally, or are doing anything involving long distance with some hills and sprints (cycling/triathlon), you will smash your glycogen levels and rely on glycogen stores to get you from A to B. Doing some training fat fuelled is good for metabolic conditioning, but you don’t do it race day, or in key sessions, in a similar vein, it would be like wearing ankle weights in training to get stronger, and lining up with them on race day. Carb units will help maintain exercise tolerance, increase time to fatigue, decrease muscle catabolism and improve recovery, talking to a sports nutritionist about how to toe the line between optimal carb & fat fuelling will get you the best of both worlds, alongside practicing your fuelling protocol for training scenarios.

            Iron levels, haemoglobin and red blood cells are all vital for oxygen transport, get a blood test, see where you’re at, you can likely raise it, if you can, do. Get your red meat, green veg and adequate protein and calories in the hatch, and consider an iron supplement for a course, and take a break. Repeat bloods are a good idea to see how your progressed, as red blood cells have a lifespan of about 12 weeks, so changes don’t really occur for about 3 months.

            Now to the bad and unnecessary, and these are ones I see quite a lot, the first being high dose Vitamin C or antioxidants, the effervescent type, which I see people taking on the way to training. Think about this, antioxidants help to alleviate oxidative damage, so they may limit the metabolic stress and acid build-up that occurs with exercise, theoretically making you perform better and recover better, or so the legend goes. Let me put it this way, if I were to attach a small hidden motor onto your bike, you would perform much better, and recover better, training would be easier, but what would be the point? Unless your goal is to sit on an uncomfortable seat for hours on end and move as fast as possible, in which case you should get a motorbike. If you take something that takes away or drastically reduces the stimulus (localized muscle fibre damage and oxidative stress), you don’t get anything to adapt to or recover from, and you have more or less wasted your time. Taking high dose antioxidants takes away the gains you get from training, not totally, but to a certain extent, also, it isn’t worth the potential diarrhoea, and to note, you don’t need high dose vitamins to boost your immune system, you need adequate vitamins, only a deficiency or overload will cause issues. In terms of totally unwarranted, it is electrolyte tablets, if you eat fruit and veg, you get many of your electrolytes, and you likely sprinkle salt on your food, you don’t need electrolyte tabs. Sodium is the major concern, as it is lost in sweat, but sports drinks/gels and powders contain it, and normal Western civilized folk actually consume in excess of sodium intake recommendations, you simply don’t need the tablets, especially if you are doing something that is less than 90 mins in duration. If you are doing an ironman, or huge stage cycle, you may lose some more potassium that would need replacing, however, many sports fuels contain this in minor amounts, and potassium deficiency is incredibly rare. Bottom line, ditch the electrolyte tablets, stick to sports products with electrolytes and carbs (TORG energy/HIGH5/Tailwind etc.)

            I hope this helps, there are many more supplements, there are tonnes of totally useless ones, and potentially some more that could make this list in years to come, just because a bottle says something, or the claim seems super legit, does not mean it is. Always think, is this relevant for me. For help tailoring a supplement guide to support your goals, get in touch!

Thanks for reading,