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  • Writer's pictureAnnie Bothma


Updated: Mar 1, 2023

- Annie Bothma, IOPN Sports Performance Nutritionist (EQF Level 7. Masters), Running Coach and Elite Marathon Runner

With the upcoming Two Oceans Marathon (TOM) on the15th of April 2023, I will do a series in collaboration with the MAKING A RUNNER PODCAST that will aim to help you prepare for the start line, covering all you need to know when it comes to nutrition.

In this week's podcast, Nic & Davey will talk you through how to train for the TOM and breakdown the course profile so you can know what to expect on race day.

While, my goal with this post will be get to start thinking about training your gut, not just your legs and lungs! I will also breakdown the basics when it comes to fuelling for endurance training and what you need to pay attention to on a day-to-day basis when it comes to nutrition and hydration.


If you are one of those athletes who only starts thinking about their nutrition the week, or worse, the day before race day, you are missing out on some serious performance benefits and may even run the risk of ruining your race!

Nutrition and training should go hand-in-hand: the day you start training for your race is when you should start thinking about your race day nutrition. In fact, it even goes beyond that, you need to make sure you are fuelling enough day-to-day to sustain the hard training over the upcoming weeks and months ahead.



In my practice, the biggest mistake I see athletes make is to under-fuel their training. Most athletes simply don't understand just how much energy their body needs to sustain them through marathon or ultra marathon training.

In fact, often runners think training for a marathon or ultra-marathon is a good way to lose weight. I hate to spoil it for you, but training for a marathon or ultra isn't the most effective way to lose weight, especially not if you wish to perform on race day! Weight-loss and performance are two completely opposing goals, that should rather be approached at different times. You won't perform at your best while your body is in a calorie deficit.

You need enough energy to run faster and further, but also to recover appropriately after hard training sessions. You won't be able to sustain the hard training that is required to run at your best come race day if your daily fueling practices don't support the training you are doing. In fact, you may not even make it to the start-line, because you may end up sick or injured along the way!


Just like you would not go on a road-trip with an empty fuel tank, it is also not a good idea to go for a long run before having a small meal or snack. Athletes should prioritize nutritional intake prior- and post-exercise; as well as during prolonged exercise sessions. Athletes should avoid fasted exercise sessions, since it does not only compromise your ability to hit your target intensities, but also compromises your recovery after training.

Furthermore, since it has been shown to be extremely harmful for bone metabolism and could increase your risk of developing a bone stress injury like a stress response or stress fracture. Doing fasted training sessions on a regular basis may negatively influence an athlete's hormonal profile, which may especially be detrimental in the long-term for female athletes.


Despite all the conflicting messages you may receive on social media about carbohydrates the science is still clear that carbs are key for maximizing endurance performance. You may hear or read about athletes who went "low-carb" and are still performing well or think if you consume less carbs you will "burn more fat" for fuel. If you look at what the best in the world are doing, dive into the research on carbohydrates or low-carb diets in athletes, you will quickly come to the conclusion that CARBS ARE STILL KING!

Carbohydrates have been proven to be the main fuel source during endurance exercise, especially when competing at a high-intensity and performance is the main goal. Diets high in fat have not been proven to be advantageous for athletes or show any enhancement in performance in endurance events. Long term adherence to a Low-Carb High-Fat (LCHF) diet may have even more negative health implications such as LEA, GI disturbance, compromised bone health and immune system, illness or injury, poor recovery, and mood disturbances.

Training with carbohydrates will help facilitate training adaptations and lead to a better performance on race day. Carbohydrates are the main fuel source at high intensity exercise above 70% of VO2 Max, so if you want to run faster, carbs are the way to go! Basically what it comes down to is, if your goal is performance, even if you are not an elite athlete trying to get onto the podium, you need to eat a diet rich in carbohydrates if you want to get the most out of yourself during training and on race day!


Proteins perform a host of very important cellular functions within the body such as participating in biochemical reactions, transporting and storing substances, maintaining structural integrity, signaling between and within cells, and producing movement. For athletes, protein is very important for recovering between sessions, building lean body mass and adapting from hard training.

Muscle protein synthesis (MPS) is the metabolic process that describes the incorporation of amino acids into bound skeletal muscle proteins. Building skeletal muscle requires a daily rate of MPS that surpasses the increase in muscle protein breakdown. In the hours following exercise, an increase in MPS that ensures a positive protein balance is dependent on the ingestion of protein. In addition, the rate and availability of essential amino acids, and the leucine content of the protein source are key factors that determine the magnitude of MPS post-exercise.

When it comes to protein we need to consider the three T's:


  • The recommend amount of protein for endurance athletes is 1.2-1.7g/kg of body weight.

  • Vegans need to consume a higher quantity of plant-based proteins per meal and at snacks (compared to animal-based proteins) to compensate for reduced digestibility and low-biological value.


  • Plant foods commonly contain a lower concentration of essential amino acids and leucine content, as well as a reduced digestibility compared to animal proteins and are therefore inferior for increasing rates of muscle protein synthesis (MPS) compared to animal protein sources.

  • It is advised to consume a mix of plant based foods such as grains, legumes, nuts and seeds on a vegan diet to ensure that all essential amino acids are present throughout the day, and that adequate BCAA's are consumed to support recovery and adaptation from training.


  • Try to consume 0.3g/kg of protein or around 25-40g of protein from a complete protein source containing all the essential amino acids after training.

  • Consume frequent doses of protein at meals and snacks throughout the day.

  • This is a practical way to ensure a full spectrum of essential amino acids is available within circulation to support MPS. This should include pre-sleep feeding in the evening, as recovery and muscle protein synthesis continues through the night.


The role of fat in the diet is an area of much debated discussion and whether saturated fat consumption are truly that harmful is not universally accepted. Indeed, in some cases, high-fat diets have even been promoted for health or weight-loss reasons. Interestingly, research has indicated that low-fat dieting might negatively influence sex hormones in males and females, which may be of particular interest to athletes needing to maximize lean body-mass gain and adaptations from hard training.

When you are considering the health benefits of dietary fat, it is perhaps more important to think of the quality and quantity of fat that is being consumed. Achieving recommended values of 0.5-1.5 g/kg per day (or roughly 30% of daily caloric intake) is a good estimate for athletes to aim for. Ideally the majority of this should come from unsaturated-fats like olive oil, avocados, nuts and seeds.

Special consideration also needs to be ensured adequate amounts of omega-3 fatty acids are present in an athletes diet. The consumption of omega-3 fatty acids has also been likened to improved cardiovascular health, reduce inflammation, increased immunity and reductions in chronic disease. Of particular interest to athletes, may be the effects omega-3 acids may have to increased nitric oxide production and improved heart-rate variability.

Your body cannot produce essential omega-3 fatty-acids on its own, you must get them from your diet. The best-known sources of omega-3 fatty acids are fish oil and fatty fish such as salmon, mackerel, trout, and tuna. Therefore, if you are a vegan athlete or just don't like eating fish, you may need to consider adding an omega-3 supplement to your routine.


Athletes should aim to be fully hydrated before they train or compete, because the body cannot adapt to dehydration. If you don't start exercise in a well-hydrated state your training quality will suffer and so will your performance on race day.

Dehydration will significantly impact the athletes performance by:

  • Reducing blood-volume

  • Decreasing blood-flow to the skin

  • Decreasing sweat-rate

  • Decreasing heat dissipation

  • Increasing body core temperature

  • Increasing the rate of muscle glycogen use

Dehydration will also increase GI distress during prolonged exercise in the heat which will result in less blood flow to the intestine by reducing total blood volume. This will further impact the athlete’s ability to fuel and hydrate sufficiently creating this vicious cycle of depletion and accelerating the increase in dehydration. Of course, this will also significantly impact the athletes performance and may even lead to a dreaded DNF!

Dehydration will also have negative effects on the gastrointestinal system such as:

  • Nausea

  • Vomiting

  • Stomach pain

  • Bloating

  • Decreased appetite

A decrease in performance will be noticed at around 2-3% of body-fluid loss and could increases the risk of developing heat illness. On the flip-side drinking too much can also be harmful leading to hyponatremia. Hyponatremia refers to a diluted blood sodium concentrations, and can have very serious or potentially live-threatening consequences.

For this reason it may be beneficial for athletes to rehydrate during training and racing with sports drinks appose to just plain water to counteract fluid losses. Sports drinks that contain sodium and other electrolytes, as well as carbohydrates, This is ideal since the presence of small amounts of glucose and sodium tends to cause an increase in the rate of water absorption compared with pure water alone.

Benefits of fluids with added sodium and other electrolytes:

  • Increase palatability.

  • Maintain thirst (and therefore promote drinking)

  • Prevent hyponatremia (diluted blood sodium)

  • Increase the rate of water uptake.

  • Increase the retention of fluid.


Adequate micronutrient intake is important for all athletes who wants to stay healthy and perform at their best, but it does not need to be hard. In fact, if you are eating a balanced diet and consuming enough calories for your physical activity level and to support your health, you are most likely meeting your daily micronutrient requirement already.

Just simply, adding a little bit of color to all your meals and snacks is an easy way to help you get a variety of micronutrients in your diet. Slice a banana on top of your peanut butter toast; add some spinach to your post-workout smoothie; add some sliced tomato next to your eggs; and throw in some berries to your oatmeal. It does not have to be hard or fancy to get more nutrients into your diet.



Just like you won't start training for a marathon the week before the race, you shouldn't just start thinking about nutrition the week leading up to the big day. Neither would you wear a pair of brand new shoes on race day...So, why would you try out new gels, drinks or other food the days prior to on race day?!

In the same way you train your legs and lungs to handle the steep climbs on Chapman's Peak, you also need to train your gut to take on nutrition while you are busy running. Over the course of months you train your muscles to tolerate more training, but you also need to train your gut to tolerate food and fluids while you exercise. By gradually increasing the amount of fluids and food you ingest pre- and during exercise you can also increase the amount you are able to consume. This is a strategic approach that may help increase the gut’s capacity to absorb carbohydrates during exercise. This may reduce the residual volume in the intestine and reduce the risk of GI discomfort or problems during exercise.


Prolonged exercise sessions is actually a stressful experience for your gut. Just like your muscles take a beating when you are pounding the pavement for hours on end without stopping, your gut will also take some of the damage. When you are training, blood-flow gets shunted away from the gut to the muscles making it harder for your body to digest and absorb nutrients for energy.

The good news is that carbs can protect your gut. Frequent and consistent consumption of carbohydrate during exercise is a protective strategy against GI disturbance, as a result of the increased chyme production.

Increased intestinal carbohydrate transport activity and carbohydrate post-absorption stimulate nitric-oxide induced vasodilation, the most potent stimulator for increasing postprandial microvascular blood flow in intestinal villi. Carbohydrate intake during exercise has the ability to maintain splanchnic perfusion and improves intestinal permeability in response to exercise stress and NSAID administration.


It would be beneficial to identify your individual carbohydrate intake tolerance levels in terms of the quantity and quality during exercise before race day arrives. Figuring out what works best will reduce the likelihood of GI issues ruining the race. Test out many different brands to find out which ones you like and would allow you feel and perform at your best. These should be easy to digest carbohydrate-rich options with minimal fat, fibre and protein as these slow down digestion. Sports foods such as gels, energy chews, sports bars and sports drinks are suitable choices and easy to carry on the run course. If you are planning to ingest more than 60 g of carbohydrates per hour, use multiple-transportable carbohydrates, like a combination of glucose and fructose, to fuel your run.


Don't let your nutrition be the thing standing in the way to achieving success on the big day! Reap the rewards of your training by optimizing your daily nutrition so you can recover faster and train even harder!

Set yourself up for success by training your gut during the months leading up to race day. Allow your gut to adapt, just like your lungs and legs, by experimenting with pre-race and race-day nutrition and hydration multiple times during training before the big day arrives.

Stay tuned for the upcoming episodes in the TOM SERIES on the MAKING A RUNNER PODCAST and subscribe to Annie's Athletes to not miss a post.

If you would like to work with me to nail down your nutrition as an endurance athlete or you need a running coach to help you prepare for your upcoming race, please click on the link below to learn more about the services I offer.



  • Craig Sale, Kirsty Jayne Elliott-Sale, "Nutrition and Athlete Bone Health," Journal of Sports Medicine, 2017, available online at

  • Alex E. Mohr, "The athletic gut microbiota," Journal of the International Society of Sports Nutrition, 2020, available online at

  • Wiley Barton, "The microbiome of professional athletes differs from that of more sedentary subjects in composition and particularly at the functional metabolic level," 2016, Nutrition Journal

  • Nicholas P West, Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomized control trial in athletes, West et al. Nutrition Journal, 2011, available online at

  • David Rogerson, Vegan diets: practical advice for athletes and exercisers, 2017.

  • Asker Jeukendrup, Micheal Gleeson, Sport Nutrition, Third Edition, 2019

  • Rachel Link, The 7 Best Plant Sources of Omega-3 Fatty Acids, 2021.

  • Burke, Carbohydrates for training and competition, 2011

  • Murray, Fundamentals of glycogen metabolism for coaches and athletes, 2018

  • Hearris, Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptation, 2014

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