Nutrition for Your Race

From 5K to Ultra Marathon

There’s incredible wisdom in the adage, “Nothing new on race day.” When it comes to race nutrition, you should practice your race-day food and fluid strategy during your training. 

Your nutritional needs depend highly on your metabolism, food tolerance, and preferences. They can also vary based on the type of event you participate in (e.g., short, long, or ultra distance; trail or road; running, cycling, or triathlon) and on the conditions (e.g., heat, elevation, etc.).

The guidelines in this article encourage high-carb availability for your race to promote optimal performance. However, if you are fat-adapted, the suggested carb intake might be too high for your metabolism. That’s why practicing your nutritional intake during training sessions or less important races is important. Testing your strategy allows you to gauge your body’s response and adjust to your individual needs.

A recent study analyzing the nutritional intake of 11 trail runners during competition observed an average carb intake of 14.93 g/h, 146.42 mg/h for sodium, and 399.73 mL/h for water, which was lower than the current scientific recommendations for carb and sodium, while at the same level for water.1You should see those guidelines as a starting point but adapt them to your experience through trial and practice. Always start with a lower dosage, and increase progressively as you practice, always basing adjustments on your personal gut tolerance. Consistent practice will encourage GI adaptations, allowing you to increase your carb intake and achieve better performance without GI discomfort. 

Refer to Figure 1 – Macronutrient and Fluid Intake Recommendations For Endurance Training, Event Fueling, and Recovery for a helpful summary.

You can also seek guidance from a nutrition professional to help establish your ultimate race nutrition strategy.

Pre-Competition Nutrition

Proactive preparation

For events lasting less than 90 min, we recommend replenishing your muscle and liver glycogen stores by consuming a carb-rich diet the previous day with a minimum of 6 g/kg and up to 7-12 g/kg of carbs.2,3 

For events lasting more than 90 min, “carb loading” is recommended 36 to 48 hours before the competition. For effective loading, you should consume 8-12 g/kg of carbs per day with an exercise taper.2,3,4 Select carb-rich foods and fluids that are easily digestible to ensure your fuel targets are met. You don’t need to eat more than usual; instead, adjust your diet to include more starches and sugars while cutting back on protein and fat. Good carbs include bread, pasta, rice, potatoes, fruit juices, smoothies, jams, honey, or energy bars. Be careful with your pre-race dinner, avoiding fiber, fat, or spices that may cause gut discomfort during your race. Do not improvise at the last minute! Try your pre-race dinner during your training, ideally the night before a long run. 

Pre-event fueling 

Endurance events typically start early in the morning, so your liver glycogen will be slightly depleted following an overnight fast. To prepare for this, we recommend topping off your liver glycogen by consuming 1–4 g/kg of carbs 1-4 hours before your event.2,3

Again, you may want to practice your pre-race breakfast during your training, so you can find what works best for you. You should limit fat and fiber, no matter what you choose, while still getting enough nutrition density. The best options include oatmeal and banana (if you can handle some fiber and eat your breakfast early enough to allow digestion), low-fiber bread with jam or honey, a fruit and protein powder smoothie, or a sports drink. To be adequately hydrated before your race, drink 0.5L of water 1-2 hours before the race.

Approximately 30 minutes before your race, you may want to sip on a hydration drink, preferably one that’s low in carbs and high in electrolytes. You can also eat some gel, half an energy bar, gel, or a few chews 10-15 minutes before the start.

During-Competition Nutrition

Fueling recommendations per event duration 

If your event lasts less than 45 minutes, there is no need for any carb intake during your race. Your glycogen stores will be enough to fuel your effort. 

If your event lasts between 45 and 75 minutes, you will probably perform at a relatively high intensity and benefit from some carb intake or a carb mouth rinse to achieve better performance. 

Studies have shown that carb mouth rinses without actual ingestion during endurance exercise can stimulate parts of the brain and central nervous system and reduce perceived exertion and increase performance.2,4,5 Frequent carb mouth rinses (every 5-10 minutes) instead of fueling can elicit reliable performance gains without adverse GI symptoms.5

If your event will last more than one hour, you will need to adopt a fueling strategy to maintain your carb availability.

For an event lasting 1 to 2.5 hours, experts recommend consuming 30-60 g/hour to maximize glycogen sparing. The longer the event, the higher your carb intake should be. 30 g/hour should be sufficient for events lasting around one hour, but you should target 60 g/hour for events closer to two hours. 

You should choose carbs that are absorbed and oxidized rapidly, such as glucose, sucrose, or maltodextrin. You can choose between liquids or solids — sports drinks, gels, or low-fat, low-protein, low-fiber energy bars work well. If you decide to replenish with liquids, you can reach the proper levels by sipping a homemade or commercial sports drink every 15 minutes.2,3,4

For an event lasting more than 2.5 hours, a higher carb intake from 60-90 g/hour will give you optimal performance. The upper limit depends on whether you consume a single carb source or a mix. 

If you consume a single type of carb (e.g., glucose, sucrose, or maltodextrin), even though those carbs can be absorbed quickly, they cannot be oxidized at a higher rate than 1.0-1.1g/minute. Due to this, there’s no point in consuming more than 60 g/hour. 

Your strategy should change if you consume a carb mix like glucose and fructose, maltodextrin and fructose, or glucose, sucrose, and fructose. Glucose and fructose are absorbed via different intestinal transporters (SGLT1 and GLUT5, respectively), which means more carbs will be absorbed, resulting in higher oxidation rates (about 1.2–1.3 g/minute). As a result, carb combinations are often better tolerated by the gut. As such, we advise consuming a carb mix of up to 90 g/hour to achieve optimal carb availability for an event longer than 2.5 hours.

With such high-carb intakes, you want to routinely practice your fueling plan during training or less important races to assess your GI comfort and the type of carbs you tolerate best (solid, gel, liquid, or a combination).2 By practicing your fueling strategy regularly, you will enable GI adaptations that optimize carb absorption and mitigate GI distress, allowing you to increase your carb intake gradually. 

For events lasting more than 6 hours (ultramarathons and Ironman races), your nutrition goal goes beyond achieving optimal performance. It focuses on minimizing your calorie deficit and keeping you hydrated to sustain the long hours and finish strong. 

You should aim to consume 150-400 Kcal/hour with 30-50 g/hour of carbs and 5-10 g/hour of protein and fat. You can get these nutrients from various calorie-dense foods (savory foods are ideal for longer races) and drink 450-750 mL/hour (or 150–250 mL every 20 minutes) of fluids combined with electrolytes. If the weather conditions are hot and humid, you should monitor your electrolyte and sodium intake and aim at ingesting 500-700 mg/L of sodium.

GI distress is common in longer races and is often a cause of non-completion. Progressive gut training during your training is critical to avoid GI problems during the race. If you are still susceptible to GI discomfort after gut training, you may want to try a short-term low-FODMAP diet (fermentable oligo-, di-, monosaccharide, and polyol) for 3-6 days before and during your race. Avoiding those types of carbs may help alleviate your symptoms. If you experience GI distress during the race, avoid highly concentrated carbs while maintaining a minimal calorie intake of 200 Kcal/hour and minimizing dehydration.

If you want to take supplements during your race, small caffeine doses (1-2 mg/kg, or 70-140 mg for a 70 kg athlete) have proven beneficial, especially in the latter stages of longer events (> 24 h) when sleep deprivation may impair your performance and compromise your safety. However, data that supports other supplements, such as ketone esters, MCTs, or vitamins, are limited.6


The recommended fluid intake during a race is typically between 400-800 mL/hour, regardless of the event type and duration. However, the ideal intake depends on the athlete’s physical variations (e.g., sweat rates, sweat sodium content, exercise intensity, body temperature, body weight, kidney function) and race conditions (e.g., humidity, environmental temperature, etc.). You should identify your hydration needs during practice by monitoring your urine color (it should be pale yellow) and checking your body weight pre- and post-exercise. With that data, you can customize your race fluid intake based on your experience.2 

While it is critical to stay well hydrated during your event, drinking too much dilutes sodium levels in the blood and can result in a dangerous medical condition called hyponatremia. You should complement your fluid intake with electrolytes (sodium, potassium, calcium, magnesium, and chloride) to compensate for the electrolytes lost in sweat. Sodium intake, in particular, should be between 300-600 mg/hour (1.7–2.9 g salt). As for total fluid intake, those numbers are specific to each individual and should be customized based on your own experience.2 

Post-Competition Nutrition

Good nutrition after your race is critical for better recovery. You want to refuel, replace muscle glycogen, and provide protein for muscle building and repair. You may eat a light meal right after your race or opt for a recovery snack (e.g., your favorite drink or bar containing a mix of carbs and protein) when you finish. Whichever option you choose, you should follow it with a full meal within two hours after your event. Enjoy your recovery meal, and make sure it contains carbs, protein, and vegetables. You should also drink enough water to replace approximately 150% of the fluid you’ve lost based on your body weight.


This article concludes our series on optimal race nutrition. Hopefully, you are better informed on how your nutrition can influence your performance and better equipped to implement your own nutrition strategy for your upcoming training and events. As always, we are here to assist you throughout this process. Please reach out with any questions. Our team can work with you to customize a nutrition plan that will best support your training, your races, and your health.


  1. Jiménez-Alfageme R, Aguirre López L, Mielgo-Ayuso J, Martínez Sanz JM. Análisis de la ingesta nutricional en corredores de montaña durante una prueba deportiva [Analysis of nutritional intake in trail runners during competition]. Nutr Hosp. 2021;38(2):321-327.
  2. Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019;11(6):1289. Published 2019 Jun 7. doi:10.3390/nu11061289
  3. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine joint position statement. Nutrition and athletic performance. Med Sci Sports Exerc. 2016;48(3):543-568.
  4. Casazza GA, Tovar AP, Richardson CE, Cortez AN, Davis BA. Energy availability, macronutrient intake, and nutritional supplementation for improving exercise performance in endurance athletes. Curr Sports Med Rep. 2018;17(6):215-223.
  5. Getzin AR, Milner C, Harkins M. Fueling the triathlete: Evidence-based practical advice for athletes of all levels: Evidence-based practical advice for athletes of all levels. Curr Sports Med Rep. 2017;16(4):240-246.
  6. Tiller NB, Roberts JD, Beasley L, et al. International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr. 2019;16(1):50.

Nutrition for Optimal Recovery

Preventing Relative Energy Deficiency

As you embark on an intensive training season, be on the lookout for signs of overtraining or Relative Energy Deficiency in Sport (RED-S). Symptoms may include fatigue, loss of performance, mood disturbance, illness, or injury, and they can be damaging to your exercise performance and your health. But as you train, it’s important to remember that RED-S can be difficult to avoid because you may start experiencing it before you notice any symptoms.  

Like most endurance athletes, you probably have a well-thought-out training plan with rest periods between sessions and recovery days that should prepare you to be at your best on race day. However, even the most detailed training plans can’t account for the fact that you are a unique individual with your own range of motion, psychological state, illnesses, nutrition, hormones, genetics, and nervous system activation. All of these factors influence how you respond to training. A heavy training schedule can create excess stress on your body, which can be exacerbated by other stressors, such as work pressures, family commitments, or lack of sleep. If you combine these stressors with a sub-optimal diet that fails to cover your energy needs or provide enough nutrients to support an increased energy demand, you may be at risk of overtraining or relative energy deficiency. 

This article will discuss Relative Energy Deficiency in Sport (RED-S), how to identify its symptoms and help you understand the potential health consequences. We will also explore how proper nutrition can help you mitigate the risks, recover well, and stay healthy during your training season.

Relative Energy Deficiency in Sport (RED-S)

  1. What is Relative Energy Deficiency in Sport (RED-S)?

RED-S is the imbalance between your food intake (energy and nutrient availability) and what your body requires to support your exercise and life-sustaining activities. It can be due to excessive exercise, inadequate nutritional intake, or insufficient recovery. 

When the energy availability is too low, the body enters into an “energy-saving mode” in which hormone production and metabolic processes are impaired, affecting all systems throughout the body (reproduction, growth, cardiovascular, immune, skeletal, and muscular). 

Over time, this imbalance can adversely affect all aspects of sports performance (see Figure 3 – RED-S Potential Health Consequences and Performance Effects). An athlete continuously training with low energy availability may experience poor performance, mood disturbances (anxiety, depression), poor cardiovascular health, increased injury risk, poor immune health, and hormonal and metabolic disruptions. Impaired bone health is another significant implication of RED-S: hormonal disruptions impact bone mineral density, increasing fracture risk. I may also prevent young athletes from reaching peak bone mass and cause irreversible bone loss in senior athletes.1

Potential Health Consequences of Relative Energy Deficiency in Sport1 


•Menstrual Function

•Bone Health



•Growth and Development





Potential Performance Effects of Relative Energy Deficiency in Sport1

•Decreased Glycogen Storage

•Decreased Muscle Strength

•Decreased Endurance Performance

•Increased Injury Risk

•Decreased Training Response

•Impaired Judgment

•Decreased Coordination

•Decreased Concentration



Figure 3 – RED-S Potential Health Consequences and Performance Effects

  1. RED-S or Overtraining?

You may be more familiar with terms like “overtraining” or “training overload,” which describe athletes who have “burned out” due to excessive training load and insufficient recovery. Overtrained athletes typically experience health decline, fatigue, performance drops or plateaus, mood disturbances, and increased injury and illness. 

You may notice similarities with the symptoms for RED-S. This is because the underlying issue is the same: affected individuals have metabolic and physiological imbalances that interfere with normal health functions and limit their performance. In many cases, overtrained athletes are misdiagnosed, and the symptoms they experience are due to under-fueling.2 In many cases, it’s simply a matter of terminology where sports dietitians refer to RED-S and sports scientists refer to overtraining. In both cases, achieving optimal nutritional intake can help alleviate those disturbances. 

  1. Assessing RED-S symptoms: Are you at risk?

While energy deficiency can be created intentionally (e.g., deliberately restricting calorie intake to lose body fat), it’s often unintentional — especially during heavy training periods where it can consume all the calories your body needs to function, let alone exercise. You may not see any symptoms at first, but they will appear if you continue under-eating relative to your training for several months. 

As your body tries to compensate for the excess loads, your sympathetic nervous system activity will increase. The first signs you may notice are a reduction in heart rate variability or an increase in resting heart rate. You may also produce more cortisol (the stress hormone) and notice that you need more carbohydrates during exercise. Of course, you may just notice that you feel more fatigued after your workout. For women of childbearing age, loss of menstrual periods is a typical sign of RED-S. Struggling to improve sports performance or persistent fatigue are also good indicators. 

Other signs of RED-S include:


•Anxiety or Depression

•Weakened Immunity

•Muscle Aches 

•Higher Susceptibility to Injury 

•Disrupted Sleep

•Altered Appetite1 

If you notice any of these signs, you should re-evaluate your training load, your periodized nutrition, and your recovery. Don’t wait for your performance to drop or for an injury to happen before you take action! 

Optimize Your Nutrition for Best Recovery

  1. Check your energy balance. 

Start your nutrition evaluation by looking at your approximate energy intake compared to your energy expenditure. According to the International Society of Sports Nutrition (ISSN),3 a regular diet is between 1800–2400 kcals/day (or 25–35 kcals/kg/day for a 50–80 kg individual), but you may expend 600–1200 kcals or more for each hour of exercise based on the intensity. So depending on your training load, you may reach a total caloric expenditure of 2000–7000 kcals/day (or 40–70 kcals/kg/day for a 50–100 kg athlete).

For optimal health and performance, we recommend staying in energy balance for most of the training season, limiting caloric deficits to 250-500 kcal/day, and saving fat loss for the off-season. You should assess your food intake versus your energy expenditure for a short period.4 A simple approach could be to use an app like My Fitness Pal to track your weekly food intake and estimate your energy expenditure using a device such as a sports watch, smartwatch, or Fitbit. If you observe significant energy deficits, you should address them by increasing your food intake, reducing your training load, or a combination of both.1

  1. Tailor your carb quantity and timing to your training.

You should always consume enough carbohydrates to meet the requirements of your training program. To accomplish this, we recommend ingesting 6-10 g of carbs per kg of body weight per day during training phases that require one to three hours of moderate to high-intensity exercise per day. Carbohydrate consumption at this level will restore your pre-exercise glycogen stores for the next day.5,6,7

You should also try to schedule your carb intake around your training sessions to ensure high-carb availability for high-intensity or long-duration training. You can do this by consuming carbs before and during those sessions: 1-4 g of carbs per kg of body weight 1-4 hours before the session, and 30 to 60 g/hour of carbs for workouts lasting more than one hour. You also want to optimize the replenishment of muscle glycogen stores between workouts, especially if you train daily or twice a day. Carbohydrate intake in the first hours following exercise is essential to maximize glycogen resynthesis. If your recovery time is less than four hours, you should implement a speedy refueling with 1.2 g of carbs kg per hour for the first few hours post-exercise. The highest glycogen synthesis rates are obtained when ingesting carbs at 15-30 minute intervals in the first 3-5 hours of your recovery period.5,6,7This is an excellent time to include high glycemic foods, including sport nutrition products such as bars, gels, or drinks.

  1. Optimize your recovery nutrition

In addition to the recommended carb intake, the following foods can help your recovery.


Protein is beneficial for proper recovery as it boosts glycogen repletion and stimulates muscle protein synthesis. 

•You can boost glycogen repletion by reducing your carb intake to 0.8 g/kg/h and combining it with 0.2–0.4 g/kg/h of protein.

•Post-exercise protein with a high leucine content (700–1300 mg) within the first two hours can stimulate muscle protein synthesis and recovery. Maximal stimulation of muscle protein synthesis can be reached with a protein intake of approximately 0.25–0.30 g per kg of body weight per meal.5

•Consume frequent meals during your recovery period to ensure optimal muscle glycogen repletion and protein synthesis due to high plasma glucose, insulin, and amino acid availability.6 


If you cannot tolerate high carb doses, consider adding caffeine (3 mg/kg, up to 8 mg/kg), as it will boost glycogen repletion by up to 66%.5Caution is required, though, as caffeine can be toxic when consumed in high doses. 


Intense exercise will increase oxygen consumption in your muscles, raising free radical and reactive oxygen species (ROS) levels. An excess in oxidant load will delay recovery. To counter this effect, consume high-antioxidant foods (such as cherry juice, berries, pecans, broccoli, or dark chocolate) to improve recovery.5


Omega-3 from fatty fish (e.g., salmon, sardines, mackerel), seafood, grass-fed beef, or nuts have anti-inflammatory effects that have proven beneficial against inflammation and oxidative stress caused by intense exercise.


Studies have shown that supplementing with creatine can enhance recovery from intense exercise by increasing glycogen storage and muscle protein synthesis. Creatine is also known for its ergogenic effect in endurance sports.7,8

  1. Consume nutrient-dense foods and watch for potential deficiencies.

Opt for good quality, nutrient-dense foods, such as vegetables, fruits, legumes, whole grains, nuts, seeds, fish, meat, eggs, or dairy products, to obtain the vitamins and minerals needed to support your activity levels.

Your exercise increases your oxidant load, and you should therefore choose minimally processed foods and avoid foods that may increase oxidative stress. A diet rich in fruits and vegetables is particularly beneficial as they are high in antioxidants such as vitamins C and E.9

Eating a variety of foods from each food group is an excellent way to ensure you consume all the essential nutrients. Generally speaking, you should not exclude whole food groups unless you have a medical condition. 

As an endurance athlete, you’ll also want to be careful to avoid common deficiencies, including iron, vitamin D, calcium, and some antioxidants such as vitamins E and C.9


Iron is essential for oxygen transport throughout the body, and, according to experts, athletes have more significant iron requirements than the general population, with female athletes requiring up to 70% more. As a result, iron deficiency is common in endurance athletes, especially females. Causes for iron deficiency are various, including heavy menstruation, inadequate dietary intake, gastrointestinal losses, and intravascular or sweat-related training losses. If you’re unsure whether you have an iron deficiency, you may want to get tested. If you are deficient, increase your intake of iron-rich foods (e.g., liver, legumes, red meat, shellfish, seeds, dark chocolate, spinach, amaranth) or supplements (under the supervision of a health or nutritional professional).9

Vitamin D

Vitamin D helps regulate many metabolic pathways, improves bone health, reduces inflammation, and supports optimal muscle function. Low Vitamin D in athletes (<30 ng/mL) has been associated with increased bone stress injury and heightened inflammatory responses post-exercise. Maintaining proper levels reduces these risks considerably. If you are prone to stress fractures or feel muscle pain or weakness, get tested regularly and be careful to notice signs of RED-S.

Pro tip: We get our vitamin D from sun exposure, but our lifestyle may limit this exposure — especially during the winter. If you’re deficient, you may want to increase your sun exposure.1,9


Like Vitamin D, calcium is critical for bone health. It is also vital for muscle contraction, nerve conduction, and clotting functions. Calcium deficiency increases the incidence of bone stress injury and contributes to low bone mineral density and low energy availability. It is recommended to consume 1500 mg per day of calcium along with 1500 to 2000 IU of Vitamin D for optimal bone health.1,9If you suspect deficiencies, always consult a health or nutritional expert before taking any supplement.


Maintaining energy availability, adjusting the quantity and timing of your nutritional intake based on your training sessions, and eating a nutritious whole-food diet can help mitigate the risks of RED-S or overtraining. 

If you are concerned about any of those aspects, please contact us. We will be happy to create a tailored nutrition plan to help you stay healthy, stay on track with your training, and be at your best every day so you can confidently approach your race day. And if you want to learn more about the ideal race-day nutrition, be sure to read our next article!​​


  1. Mountjoy M, Sundgot-Borgen J, Burke L, et al. International Olympic Committee (IOC) consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Int J Sport Nutr Exerc Metab. 2018;28(4):316-331.
  2. Stellingwerff T, Heikura IA, Meeusen R, et al. Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared pathways, symptoms and complexities. Sports Med. Published online 2021.
  3. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition. 2018;15(1). 
  4. Casazza GA, Tovar AP, Richardson CE, Cortez AN, Davis BA. Energy availability, macronutrient intake, and nutritional supplementation for improving exercise performance in endurance athletes. Curr Sports Med Rep. 2018;17(6):215-223.
  5. Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019;11(6):1289. Published 2019 Jun 7. doi:10.3390/nu11061289
  6. Fritzen AM, Lundsgaard A-M, Kiens B. Dietary Fuels in Athletic Performance. Annual Review of Nutrition. 2019;39(1):45-73.
  7. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine joint position statement. Nutrition and athletic performance. Med Sci Sports Exerc. 2016;48(3):543-568.
  8. Wax B, Kerksick CM, Jagim AR, Mayo JJ, Lyons BC, Kreider RB. Creatine for Exercise and Sports Performance, with Recovery Considerations for Healthy Populations. Nutrients. 2021; 13(6):1915.
  9. Bytomski JR. Fueling for Performance. Sports Health. 2018;10(1):47-53.

Nutrition for Metabolic Adaptation and Performance

Carb Periodization Explained

As we discussed in our previous blog, carbohydrates are the most recommended energy source for endurance athletes looking to achieve optimal performance during competitions and intense training. In recent years, however, we’ve seen more athletes turning to low-carb diets to increase their fat-burning capacity at moderate intensity and reduce the need for carbohydrates during long training and races. Others use this dietary approach to improve their body composition. Still others follow the low-carb method to avoid a high-carb diet that can result in metabolic imbalances and lead to chronic inflammation, high blood sugar, or insulin resistance. However, many of these low-carb diets are also high in fat. This poses a problem because a high-fat approach also has its drawbacks, the most obvious being compromised training quality, reduced performance at higher intensities, and diminished ability for muscle cells to oxidize glycogen efficiently.1

Periodized nutrition offers an excellent alternative to the extremes of low-carb or high-fat diets. This base phase of this approach, which is now encouraged by the sport nutrition guidelines, limits your carbs during your off-season — when your training intensity is low and can be fueled by fat — but increases your carb intake as you move into your build and peak phases, where your training requires higher intensity and longer duration. You can go one step further and adjust your carb intake for each session depending on your training goal. This practice, known as carb periodization, can produce favorable metabolic adaptations that increase fat oxidation at higher intensities, enhance exercise performance, and improve metabolic flexibility. 

Periodized nutrition offers an excellent alternative to the extremes of low-carb or high-fat diets. This base phase of this approach, which is now encouraged by the sport nutrition guidelines, limits your carbs during your off-season — when your training intensity is low and can be fueled by fat — but increases your carb intake as you move into your build and peak phases, where your training requires higher intensity and longer duration. You can go one step further and adjust your carb intake for each session depending on your training goal. This practice, known as carb periodization, can produce favorable metabolic adaptations that increase fat oxidation at higher intensities, enhance exercise performance, and improve metabolic flexibility. 

By following this periodization, you will adjust your carb intake to your training requirements and experience the benefits of optimal performance, improved training quality, and positive metabolic adaptations.2

With those enhancements in mind, let’s explore carb periodization with a focus on low-carb training, the mechanisms and metabolic adaptations in play, the potential benefits you can get from this practice, and how to incorporate it into your training and nutrition routine.

What Is Carb Periodization?

Carbohydrate periodization is the manipulation of carbohydrate availability on a day-to-day or meal-by-meal basis according to the intensity, duration, and goals you have planned for an upcoming workout. Adjusting your carb intake can enhance the desired outcome for that session.

•If you want to perform optimally, train at high intensities or for long durations, ensure high-quality outputs, reduce symptoms of fatigue and overreaching, and maximize your recovery, you should train with full glycogen stores. To accomplish this, your pre-training carb intake should be high, and you may need to supplement with additional carbs during exercise. (The standard recommendation is 30-60 g of carbohydrates per hour). You should also consume carbs post-exercise to allow glycogen restoration and proper recovery. 

•If you want to train your gut, you can increase your daily carbohydrate intake or boost your mid-exercise carb consumption to improve your gut absorptive capacity and reduce GI discomfort.

•If you want to train your race nutrition, you should implement all aspects of your race nutrition strategy (food, gels, drinks, supplements, timing, etc.) in your training session.

•If you want to enhance the metabolic adaptations of your skeletal muscle that will develop your fat metabolism, improve your metabolic flexibility, and possibly enhance your time to exhaustion during exercise and your performance, you should periodically train with low-carb availability. 1,2,3

The chart below indicates the metabolic adaptations you can expect from a workout depending on your exercise duration, exercise intensity, starting muscle glycogen, and pre-exercise nutrition.

Figure 2 – Metabolic Adaptation

Because training low has potential advantages for your performance and health, let’s explore this approach, how to include it in your training and how it can benefit you. 

Low-Carb Training 

  1. Mechanisms in Play at a Cellular Level

Low-carb training appears to enhance some molecular signaling pathways in the muscle cells, specifically those associated with adaptations that can benefit endurance sports. Exercising with low glycogen availability can activate key cell-signaling proteins (e.g., AMPK, p38, PPAR, PGC-1α) that upregulate the expression of genes involved in mitochondrial biogenesis, lipid oxidation, and angiogenesis.

•Increased mitochondrial biogenesis means more mitochondria in the muscle cells, thus greater capacity to produce cellular energy and potentially increase endurance capacity and performance.

•Increased lipid oxidation enables more fatty acids to be used for energy production at higher intensities, sparing glycogen in the process. 

•Angiogenesis supplies the muscle with a greater blood supply, which improves the delivery of nutrients and oxygen to the working muscles.1,4

  1. How To Implement Low-Carb Training

There are several ways to train with low-carb availability.

Train fasted. After an overnight fast, train before breakfast. With this method, while muscle glycogen levels may be normal or even high, liver glycogen levels will be low. This permits increased free fatty acid availability and activation of the AMPK signaling, enabling lipid oxidation and other positive metabolic adaptations. However, such adaptations are likely due to carb restriction only, as opposed to complete fasting, so you may consume some protein (e.g., 20g of whey protein) before or during the session. This approach will allow the same adaptations while improving net muscle protein balance.1,2,3

Train twice a day. Do your first workout of the day after consuming some carbs, and then don’t eat any carbs before your second workout. Your first session will lower your muscle glycogen so that you perform your second training in a low-glycogen state. This method has been shown to increase oxidative enzyme activity and fat utilization and improve exercise capacity and performance.1,2,3

Sleep low. Train in the evening, restrict carbs overnight and do a fasted session in the morning. The effect is similar to training twice a day, except that the duration with low muscle and liver glycogen is extended for several hours while you sleep. Studies using this method have demonstrated beneficial effects on cell signaling and performance.1,2,3,5

Recover low: Don’t consume carbs for 2-4 hours post-exercise, not even with your usual recovery meal. By restricting carbs post-exercise, you keep muscle and liver glycogen low, extend the availability of circulating free fatty acids for fuel, sustain the upregulation of cell signaling pathways, and boost the adaptive response to the session. Some studies have also reported an improved metabolic adaptation to exercise using this method.

Performance Benefits  

Low-carb training can improve endurance capacity and performance due to enhanced mitochondria biogenesis and increased blood supply to working muscles.1,4 However, while some studies saw performance improvements in sub-elite athletes with a Sleep Low approach,5 a recent meta-analysis concluded that evidence of performance enhancement associated with carb periodization in well-trained endurance athletes is limited. As such, low-carb training is not necessarily associated with enhanced endurance.6 That said, while not all studies have shown a long-term performance benefit, none have shown a drop in performance.

A clear benefit of low-carb training, though, is improved fat oxidation. This occurs because you are conditioning your body to use its stored fat as fuel instead of recently consumed carbohydrates.1,4 This may benefit your body composition and increase the intensity at which you can exercise while predominantly using fat as fuel, sparing glycogen stores, which allows you to last longer without carb intake during long training sessions and races. This benefit may be advantageous if you compete in long-distance events such as ultra-marathon or Ironman or if you are prone to GI issues when consuming a high amount of sports nutrition products.

Furthermore, by improving your capacity to use fat as fuel, you enhance your metabolic flexibility, a critical health marker that we will briefly cover in the last section of this article.

A Word Of Caution

While low-carb training brings benefits, you should not do every workout on low glycogen stores. First, you will lose your ability to convert carbohydrates to energy efficiently if you don’t train high-carb from time to time.1 Second, your exercise capacity is diminished in a low-carb capacity, which may compromise high-intensity training sessions. If you are unable to complete the scheduled training sessions, your long-term training and competition goals may be jeopardized.1,2 Due to these risks, we recommend you undertake only 30-50% of your training sessions with low-carb availability.2 

Metabolic Flexibility

The primary advantage of carb periodization is that it enhances your metabolic flexibility, which is a critical marker of good health. 

Metabolic flexibility refers to your body’s ability to efficiently use whatever fuel is available, fat or carbs, and seamlessly switch from one fuel source to another. Carb periodization is an excellent way to promote metabolic flexibility since it improves fat oxidation by occasionally exercising with low-carb levels while maintaining carb oxidation efficiency with regular high-carb sessions.

Metabolic flexibility provides many benefits, including sustained energy, fewer blood sugar fluctuations, reduced cravings, and improved fat-burning. As your metabolic flexibility improves, you are less likely to develop conditions like type 2 diabetes and obesity. Individuals suffering from type 2 diabetes or obesity are typically metabolically inflexible, and current research suggests that exercise and carb periodization can help improve metabolic flexibility in skeletal muscle and adipose tissue, which could make them valuable for preventing and treating metabolic diseases.7


Hopefully, you have a better understanding of carb periodization and see some potential benefits for you. While we tried to provide enough information to get you started, incorporating carb periodization into your training and nutrition routine might be intimidating. If in doubt, please reach out. We are here to support you. We can work with you to create an individualized nutrition plan and suggest a periodization that best aligns with your training plan, targeted race, and dietary preferences. 

As you refine your training diet, it’s important to remember that your recovery is just as important as your training! 

In our next article, we will discuss relative energy deficiency in sport (RED-S), its negative consequences on your performance and health, and how adequate nutrition can help mitigate the risks and help you properly recover from training. 


  1. Burke LM, Hawley JA, Jeukendrup A, Morton JP, Stellingwerff T, Maughan RJ. Toward a Common Understanding of Diet–Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. International Journal of Sport Nutrition and Exercise Metabolism. 2018;28(5):451-463.
  2. Impey SG, Hearris MA, Hammond KM, et al. Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Medicine. 2018;48(5):1031-1048.
  3. Jeukendrup AE. Periodized Nutrition for Athletes. Sports medicine (Auckland, NZ). 2017;47(Suppl 1):51-63. doi:10.1007/s40279-017-0694-2
  4. Stellingwerff T, Morton JP, Burke LM. A Framework for Periodized Nutrition for Athletics. Int J Sport Nutr Exerc Metab. 2019;29(2):141-151. doi:10.1123/ijsnem.2018-0305.
  5. Marquet LA, Brisswalter J, Louis J, et al. Enhanced Endurance Performance by Periodization of Carbohydrate Intake: “Sleep Low” Strategy. Med Sci Sports Exerc. 2016;48(4):663-672. 
  6. Gejl KD, Nybo L. Performance effects of periodized carbohydrate restriction in endurance trained athletes – a systematic review and meta-analysis. J Int Soc Sports Nutr. 2021;18(1):37.
  7. Goodpaster BH, Sparks LM. Metabolic Flexibility in Health and Disease. Cell Metab. 2017;25(5):1027-1036. doi:10.1016/j.cmet.2017.04.015

Nutrition For Your Training Days

Cover Your Bases

In the first article of this series, we set the foundation by discussing optimal nutrition for your training days. Now we will review the latest sport nutrition guidelines to help you fuel your training while staying healthy and energized for your upcoming race. 

• We will explore the following topics: 

• Your energy needs and why it is critical to meet them

• Balancing your macronutrients (carbohydrates, proteins, and fats)

• How macros impact your training and performance

• Tips to help you get your hydration right

• Benefits of periodizing your nutrition for your training

Meet Your Energy Needs

Energy availability is an essential foundation for optimal health and exercise performance.1,2 As you begin a lengthy training period, make sure that your dietary intake meets your energy requirements.

Energy deficiency during training can have negative physical and psychological consequences (e.g., fat-free mass, illness, poor sleep, delayed recovery, hormonal imbalance, elevated resting heart rate, apathy towards training, or increased stress). Any combination of these factors can compromise your training, your performance, and your health over time. If you want to optimize your training and performance, be sure to consume enough calories to offset your energy expenditure.3

Energy balance occurs when the total Energy Intake (EI) you obtain from food and fluids equals your Total Energy Expenditure (TEE), which consists of the following: 

•Your Basal Metabolic Rate (BMR): the energy required to support your life-sustaining activities, such as breathing, circulation, and cell production

•The Thermic Effect of Food (TEF): the energy used to digest, absorb, metabolize, and store food — which can vary from 3 to 10% of the energy expenditure depending on the types of food eaten

•The Thermic Effect of Activity (TEA): the energy burned during all physical activity, from simple fidgeting to the most strenuous workouts


In the general population, the BMR accounts for about 2/3 of the TEE, but it may only be 1/3 for elite endurance athletes who can have a TEA as high as 1/2 of the TEE. While your training volume and intensity may not be as high as an elite athlete’s, it still matters. Adjust your energy intake to meet your energy balance based on your training load.1,4,5 

According to the latest sports nutrition guidelines published by the International Society of Sports Nutrition (ISSN), if you exercise for 30–40 minutes three times a week, a regular diet of about 1800–2400 kcals/day (or 25–35 kcals/kg/day for a 50–80 kg individual) should meet your nutritional demands. However, if your training is more intense (2–3 hours of intense exercise per day, 5–6 days per week, or even higher volumes, such as 3–6 hours of intense training in 1 or 2 workouts, 5–6 days per week), you may expend 600–1200 kcals or more per hour during exercise. This level of effort gives you a caloric need of 2000–7000 kcals/day (or 40–70 kcals/kg/day for a 50–100 kg athlete), and your food intake should cover the additional energy expenditure.3 

To put things in perspective and better understand how your macronutrient strategy impacts your daily dietary needs, carbohydrates and proteins have 4 kcal per gram, while fat has 9 kcal per gram. Now that we have established that your dietary intake must match your energy needs, let’s examine what foods provide the nutrition to best support your activity.

Get Your Macronutrients Right

As an endurance athlete, consuming an optimal macronutrient ratio can help you reach your training goals: performance, muscle gain, or fat loss. Depending on your sport, the timing of your nutrient intake throughout the day is as important to your training and recovery as what you eat.1

That said, the quality of your food is an important factor to consider. We recommend consuming whole foods over packaged foods whenever possible. Eating a clean, nutrient-dense diet that includes a wide variety of foods rich in antioxidants, fiber, vitamins, and minerals should provide all the nutritional fuel you need to sustain your exercise and stay healthy.4 

Let’s take a closer look at the macronutrients (carbohydrates, proteins, fats) and explore how consuming the recommended quantities at the correct times can help you achieve your performance goals.


Carbohydrates are a primary energy source for our brain and our central nervous system, and they form a versatile substrate for our muscular work.1 The beneficial effects of carbs on athletic performance are well-known and supported by over 60 years of research. 

Carbs are useful for long periods of high-intensity exercise.

Fat and carbs are used as fuel when exercising at lower or moderate intensity (65% VO2max). As intensity increases (85% VO2max), carbs become the primary energy substrate. During aerobic exercises, in the presence of oxygen, carbs will produce less ATP (the energy currency of our cells) than fat: 30-32 ATP for one glucose molecule versus hundreds of ATP depending on the fatty acid length. However, ATP will be produced much faster from carbs than fat. Furthermore, when engaging in extremely high-intensity anaerobic exercises, glucose is the only substrate that will supply energy without using oxygen, generating only 2 ATP in the absence of oxygen —  but generating them hundreds of times faster than fat oxidation. As the substrate of choice for high intensity, carbs are essential to achieve speed and performance.

Carb storage is limited in our body and requires sufficient intake to avoid depletion. When ingested, carbs are broken down to glucose and stored as glycogen in our liver and muscle. Glycogen stores are limited and rapidly depleted during long and strenuous exercise. 

Glycogen depletion is an important limiting factor of performance. It is associated with fatigue and reduced work rates. At the same time, inadequate carbohydrate intake increases the perception of effort, hinders the central nervous system, and impairs performance-influencing factors such as pacing, motor skill, and concentration.

Adequate intake before, during, and after long periods of high-intensity exercise — including race day competitions — is vital to performance and recovery.3,6  As you progress in your training plan and increase your mileage, you should purposefully eat more carbs while adjusting your daily intake based on each day’s training. Carb intake should be higher on hard training days and less on easy days. The current sport nutrition guidelines recommend a daily intake of:

• 3-5 g per kg of body weight for light activity 

• 5-7 g per kg of body weight for moderate exercise (~1 h/day)

• 6-10 g per kg of body weight for vigorous exercise (1-3 h/day)

• 8-12 g per kg of body weight for very high training (>4 h/day)1,2,3,4

As you plan your carbohydrates, remember that not all carbs are created equal. They can be divided into two categories: simple carbs and complex carbs.

Simple carbs are sugars and refined grains that have been stripped of their fiber and nutrients. Omnipresent in the western diet, they are commonly found in processed foods such as soda, baked goods, fruit juice, or breakfast cereals. They are easy to digest and lead to rapid blood sugar and insulin spikes, which have been linked to an increased risk of chronic diseases, including obesity, heart disease, and type 2 diabetes. 

Complex carbs include fruits, vegetables, whole grains, and legumes. They are packed with nutrients and fiber and digest more slowly than simple carbs. They are also known for their long-term health benefits as they can help maintain a healthy weight and guard against type 2 diabetes and cardiovascular problems. 

As an endurance athlete, you can support your general health by eating nutrient-rich, unrefined carbs like colorful fruits and vegetables, whole grains (oats, quinoa, or brown rice), and legumes (beans, lentils, or peas). However, there is still a place for simple carbs in your training nutrition plan. They will release energy more quickly, allowing you to improve performance, delay fatigue, boost concentration, and decrease perceived exertion. Still, they should be consumed primarily for long (> 90 minutes) or strenuous sessions.

Since they are easy to digest, simple carbohydrates can come in handy as a pre-exercise snack — especially if you don’t have enough time to allow digestion before a long or strenuous workout. Bananas, rice cakes, white bread, dried fruits, juices, or energy bars can be good options for a quick burst of energy. 

During your training or competition, sports drinks, gels, or energy bars will provide simple carbs that maintain blood glucose levels, provide extra fuel, and spare glycogen stores. The more intense the exercise, the more carbs you need. Recreational endurance athletes should try to consume 30g of carbs per hour for low- to moderate-intensity training, increasing up to 60g per hour for high-intensity sessions. Remember that there is no need to eat anything for shorter and slow-paced sessions (less than 60-90 minutes), as your glycogen stores will be sufficient to fuel those training sessions.

In addition to fueling you before and during your workout, simple carbs can also help restore your glycogen stores rapidly if you have a short recovery window between sessions. However, if you have time post-training, you should favor complex carbs, such as whole-grain bread, whole-grain pasta, whole grains, beans, lentils, or starchy vegetables. These will replenish your glycogen stores and add healthy nutrients, fiber, and protein to your diet. Simple carbs are great for quick energy, but you should always favor real food outside your workouts.

Macronutrient and Fluid Intake Recommendations For Endurance Training, Event Fueling, and Recovery

Figure 1 – Macronutrient and Fluid Intake Recommendations For Endurance Training, Event Fueling, and Recovery


Proteins and their base components, amino acids, are essential for various bodily functions. They make enzymes, hormones, and neurotransmitters and build and repair muscles, tendons, and other soft tissues. Muscle proteins break down during exercise, and protein in the diet provides the amino acids essential for repairing and regenerating damaged proteins in the muscle. As a result, endurance athletes may require a higher protein intake than the average person to prevent muscle loss and reduction in muscle strength. The current guidelines suggest that an athlete should ingest between 1.4-2.0 g of protein per kilogram of body weight per day (an average of 75-120 g per day for a 50-80 kg individual), with higher amounts during heavy training volumes to maintain energy balance, protein balance, and muscle mass. Protein requirements also increase with age (as muscle in individuals over 53 years may be slower to respond and less sensitive to protein ingestion),3 and for those trying to lose body fat while maintaining or increasing fat-free mass. Overall, protein sources should account for about 15-30% of an endurance athlete’s total calorie intake.4

Studies have reported better results when spreading high-quality protein intake throughout the day (0.3 g per kg, or 15-25 g every 3 to 5 hours). They have also shown that consuming 30-40 g of casein protein before sleep can increase muscle protein synthesis.2,4,7

During strenuous endurance exercises that last longer than an hour, we recommend consuming 0.25 g of protein per kg of body weight per hour in addition to the standard 30 to 60 g of carbohydrates. This combination has been shown to suppress markers of muscle damage and reduce feelings of muscle soreness.2,7

While carbohydrates and fats are the predominant energy sources for training, protein can also provide fuel. When muscle breaks down during exercise, it releases amino acids that can be converted to glucose in the liver or directly oxidized within the mitochondria of the muscle cells to provide fuel. Adequate carbohydrate and fat consumption allows your protein intake to be directed towards repair and synthesis rather than being used as an energy source.2,4,7

If you want to maximize your amino acid availability and cover all your other nutritional needs, try to obtain your protein from various whole food sources whenever possible. Good options include meat, fish, dairy, eggs, legumes (lentils, peas, beans), grains, nuts, seeds, and soy products (preferably fermented, such as tempeh, miso, natto, or minimally processed soybeans or edamame). However, the amount of protein available in those different foods varies, as does the protein’s bioavailability (the measure of the body’s ability to digest and absorb the protein content). 

The best protein sources are those rich in essential amino acids, especially leucine, which are critical for achieving maximal rates of muscle protein synthesis (MPS). Animal sources are high in leucine and contain the nine essential amino acids our body needs to obtain from the diet. Plant sources, while beneficial, may be deficient in one or more of these essential amino acids or contain them in insufficient amounts. Therefore, if you follow a plant-based diet, you should combine complementary plant proteins (e.g., rice with lentils or beans) and increase your portion sizes to obtain your daily protein requirements.  

High-quality protein powders are suitable (and convenient) alternatives for meeting your protein needs. A protein shake that combines protein powder with fruits, oats, veggies, nuts, seeds, dairy, or plant-based milk can make a great recovery drink after a training session. Whey protein is rapidly digested, making it an excellent option for quick recovery between training sessions. Casein protein is slower-releasing, which is why it can be taken before bed if you want to increase MPS overnight. Vegan protein powders are also available, most including soy or a combination of pea and rice that covers all the essential amino acids.4,7


Sport nutrition guidelines recommend 20% to 35% — and no less than 15% — of your daily calories come from healthy fats. The rationale for this direction comes from the fact that fats are essential for many processes in the body, including cell membrane structure, absorption of fat-soluble vitamins, hormone regulation, brain health, and energy for muscle metabolism.

Healthy fat sources include fish (salmon, mackerel, or sardines), avocado, nuts, seeds, coconut oil, extra virgin olive oil, full-fat yogurt, or cheese. All these are high in Omega 3 fatty acids, which help endurance athletes counteract inflammation and free radical formation caused by training.4

These days, we see an increased interest in low-carb/high-fat and ketogenic diets among endurance athletes. Most use these diets to change their metabolism and improve their body’s ability to use fat as fuel at higher intensities, reducing the need for carbohydrates. These approaches can benefit those embarking on long-distance events that do not require high-intensity effort. They can also help athletes suffering from gastrointestinal distress as they can reduce carb intake during training and competitions. Other potential benefits include weight loss, improved body composition, delayed onset of muscle soreness, decreased inflammation, attenuated exercise-induced oxidative stress, improved cognition and mood, and reduced fasting glucose and insulin levels. 

That’s not to say these diets are without their concerns. First, engaging in high-intensity training in a low glycogen state will be difficult because, at a certain degree of intensity, your body will fully rely on carbohydrates to produce energy. Second, research has shown that if you don’t train with high carbs at times, you may lose your ability to efficiently convert carbohydrates to energy, compromising your performance at higher intensities. Finally, when it comes to energy production, fat oxidation requires a higher volume of oxygen than carb oxidation, which makes it less economical and reduces the beneficial impact of an increased VO2max.8 

Furthermore, such diets may cause increased satiety and reduced energy intake, which is useful for weight loss but potentially detrimental for highly active athletes who need enough caloric intake to fuel their exercise. Also, high-fat diets often reduce fiber and micronutrients (including iron, magnesium, potassium, folate, and antioxidants), which can harm the gut microbiome and iron metabolism.9,10 

While these popular diets can be helpful for those looking to lose weight or regulate issues with blood sugar and insulin function, there is not enough current evidence to support their long-term use. During base training, a short-term low-carb/high-fat diet can improve fat utilization, endurance capacity, and body composition. However, as the season progresses, you should increase your carb intake to enhance the glycolytic energy pathways needed during high-intensity competitions. 


Proper hydration is essential for endurance athletes who want to maximize their thermoregulation and exercise performance. 

When you exercise, it’s natural to lose water weight through perspiration and respiration. With this in mind, your exercise-induced weight loss should not exceed 2% of your body weight; otherwise, your cognitive function and performance may be impaired. To keep this from happening, you should follow a proper hydration strategy before, during, and after exercise based on your specific needs and fluid losses. 

Hydration needs vary from one person to the other due to differences in fluid and electrolyte loss. To determine whether you are drinking enough fluids, you can monitor your urine color (it should be pale yellow) or weigh yourself before and after exercise. Whatever method you use is far better than simply waiting until you feel thirsty. When you’re training or competing — especially at high-intensity levels —  you may have already lost too much fluid through sweat before you feel thirsty. 

Sweat is composed of water and electrolytes (sodium, potassium, calcium, magnesium, and chloride), all of which are vital for top performance. To replenish the water and electrolytes you lose during exercise, drink fluids combined with electrolytes or add a little extra salt to your diet. For a summary of pre-, mid-, and post-race fluid intake, see Figure 1 above. 

Periodized Nutrition

While current guidelines do not recommend a low-carb/high-fat approach for endurance athletes, they are more nuanced than in the past and do not suggest constant high-carb fueling either.1,11 Instead, endurance athletes are advised to periodize their dietary intake based on their training goals and race schedules to maximize exercise performance and recovery.2

As an endurance athlete, you are used to periodizing your training to maximize your performance. Your coach will break down your training season into different phases and systematically alter your sessions throughout the year, manipulating your intensity, types of exercise, duration, or frequency to obtain specific training outcomes. Periodized nutrition is a relatively new concept that uses nutritional interventions purposefully and strategically to amplify those training adaptations by targeting either a training phase or a specific session.12

Practically speaking, your training season should be broken down into training phases. Your base training typically consists of low-intensity workouts that can be fueled by fat, as they won’t require high energy intake. As a result, you won’t need as many carbs or additional energy intake during this phase. Simply consuming fewer carbs — especially refined, starchy, and sugary ones — while keeping your regular intake of protein, healthy fats, and nutrient-rich fruits and vegetables should support your performance. You may even improve fat utilization, endurance capacity, and body composition by following a low-carb/high-fat diet. 

As the season progresses, higher carb intake is necessary to improve the glycolytic energy pathways needed for higher-intensity efforts.  You will have more vigorous exercises that will burn more calories during build and peak phases, so we recommend increasing your carb intake throughout the season. Beyond just the carbs, your total calories should align with your training volume to meet your energy balance.2

Dialing in your nutrition strategy even further, you should adjust your dietary intake around each workout to match the demands and goals of specific training sessions. You want to increase your carb intake for high-intensity sessions or when you want to perform well. Conversely, you should limit your carb intake for lower-intensity sessions or when you want to trigger training adaptations. 

Because carbs are key in regulating muscle and metabolic responses to exercise, playing with your carb intake for a specific session can trigger targeted adaptations that improve your sports performance and metabolic flexibility (i.e., the ability to switch between fat and carbs as fuel sources). This practice, known as carb periodization, is the topic of our next blog. So if you’d like to dive deeper and understand how carb periodization works and how it can improve your metabolic flexibility and positively impact your overall health and performance, join me in our next blog!


Now that you have a better grasp on what your diet should look like during your training days, it’s time to step back and think about your dietary plan and how you could best apply those nutrition guidelines. The summary table above (Figure 1) can be a great tool to help you define your diet plan, so feel free to download or print it for easy reference.

Creating a personal nutrition plan based on general guidelines can be cumbersome, and we are here to assist. If you feel overwhelmed, don’t know where to start, or just need some guidance, please reach out! We can help you define your personalized diet plan based on your training, lifestyle, and preferences. We’ll work with you to ensure you can train efficiently and perform your best on race day.


  1. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine joint position statement. Nutrition and athletic performance. Med Sci Sports Exerc. 2016;48(3):543-568.
  2. Casazza GA, Tovar AP, Richardson CE, Cortez AN, Davis BA. Energy availability, macronutrient intake, and nutritional supplementation for improving exercise performance in endurance athletes. Curr Sports Med Rep. 2018;17(6):215-223.
  3. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition. 2018;15(1). 
  4. ​​Bytomski JR. Fueling for Performance. Sports Health. 2018;10(1):47-53.
  5. Heydenreich J, Kayser B, Schutz Y, Melzer K. Total Energy Expenditure, Energy Intake, and Body Composition in Endurance Athletes Across the Training Season: A Systematic Review. Sports Med Open. 2017;3(1):8. 
  6. Hearris M, Hammond K, Fell J, Morton J. Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptations. Nutrients. 2018;10(3):298.
  7. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
  8. Burke LM, Hawley JA, Jeukendrup A, Morton JP, Stellingwerff T, Maughan RJ. Toward a Common Understanding of Diet–Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. International Journal of Sport Nutrition and Exercise Metabolism. 2018;28(5):451-463.
  9. Bailey CP, Hennessy E. A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect? Journal of the International Society of Sports Nutrition. 2020;17(1). doi:10.1186/s12970-020-00362-9
  10. McSwiney FT, Doyle L, Plews DJ, Zinn C. Impact Of Ketogenic Diet On Athletes: Current Insights. Open access journal of sports medicine. 2019;10:171-183.
  11. Fritzen AM, Lundsgaard A-M, Kiens B. Dietary Fuels in Athletic Performance. Annual Review of Nutrition. 2019;39(1):45-73. doi:10.1146/annurev-nutr-082018-124337
  12. Jeukendrup AE. Periodized Nutrition for Athletes. Sports medicine (Auckland, NZ). 2017;47(Suppl 1):51-63. doi:10.1007/s40279-017-0694-2

Getting Ready For Your Next Endurance Event

Nutrition For Performance And Health

You’ve just signed up for your next race. You are eager, excited, and fully committed to the long and demanding training ahead. Now is a perfect time to think about your nutrition.

You are going to spend a lot of hours and effort training, and you want to be at your best for your race day. A proper diet will be essential to get you there.

Focusing on your daily nutrition will help you meet your energy demands for training and performance, as well as support optimal metabolic adaptations to your training, allow proper recovery, and keep you healthy.1

In this blog series, we will discuss evidence-based nutrition strategies that will help you sustain your training, enhance your metabolic flexibility, reach better performance, recover properly, stay healthy, and fuel efficiently on race day.

As you embark on this journey, though, you should be clear about your goal. What are you trying to achieve?

• Better performance? 

• Enhanced body composition and fat loss? 

• Healthier lifestyle and longevity?

It is difficult to maximize those three aspects altogether, and focusing on one can move you further away from the other two. Practices that can lead to performance gain are not always considered healthy, and reversely, focusing on fat loss or health can limit your ability to push for performance.

If your goal is performance, you may be tempted to follow the latest dietary, supplement, or training practices popular among elite athletes. But you should keep in mind that what works for them does not necessarily apply to recreational athletes. They have different physiology, metabolism, and probably different motivations. Elite athletes have a tremendous training load and exceptional physiology and are after the slightest gain that will give them the edge and a place on the podium. The gain can be so minimal that it becomes irrelevant for recreational athletes. Those practices can be difficult to implement properly on your own and may require guidance from a coach or a nutritionist. Furthermore, they might have no benefits for a recreational athlete at all or even be unhealthy. So before trying out the latest trend, ask yourself whether it is simple enough, whether it is safe, and if it will get you closer to your goal. In doubt, you should always seek assistance from a professional.

This blog series is geared towards helping you achieve your race goal. It will provide general guidelines based on the latest science to help you sustain your training, improve your performance, and stay healthy. But keep in mind that you are a unique individual, and what is recommended for the average population may not necessarily apply to you. The best is to experiment with what you are comfortable with, adjust to your personal needs and likings, and do what works best for you.

Another important consideration is that while the nutrition strategies we will discuss here can help you support your training and achieve better performance, you should keep in mind that, when it comes to nutrition, eating a good, clean diet full of nutrient-rich, unprocessed foods should always be your first priority.2

We will start our first article with an overview of what your ideal diet should look like to keep you energized and healthy during your training days. So let’s get started!


  1. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition. 2018;15(1).
  2. Bytomski JR. Fueling for Performance. Sports Health. 2018;10(1):47-53.