The advice regarding performance nutrition for runners can often be perplexing and conflicting, creating confusion. There are debates on whether increasing fat intake and limiting carbs is more effective in enhancing fat burning. On the other hand, some argue that it is preferable to increase carbohydrate consumption to ensure a readily available fuel source. Recent studies propose that the most suitable diet for the majority of runners is one that incorporates a harmonious combination of both fat and carbohydrates, leading to optimal performance.
Fat oxidation and performance
When you engage in physical activity, your body mainly relies on carbohydrates (glucose) and fat as sources of energy. Your body’s preference is to utilize blood glucose as the primary energy source, as it is the easiest to access. After that, it will tap into your glycogen reserves for fuel, but this conversion from glycogen to glucose takes longer before it can be utilized.
The issue pertaining to glucose and glycogen is that the body has limited quantities of them, necessitating the intake of external carbohydrates (such as gels, sports drinks, etc.) to replenish them. On the contrary, fat is stored in larger amounts within the body and yields more energy per gram compared to carbohydrates.
Regrettably, the issue with fat is that in order for your body to utilize it as fuel through the process of fat oxidation, sufficient oxygen is required. Therefore, it is necessary to reduce your pace and allow for the intake of adequate oxygen for this process to occur.
For short-distance runners, such as sprinters or those participating in races like the 800m or mile, this isn’t beneficial. However, for long-distance athletes, fat serves as a significant source of fuel. If you can supply enough oxygen to utilize fat, it’s possible to run for hours while burning fat as energy.
Recently, researchers attempted to answer the question of whether it is necessary or effective for researchers, coaches, and athletes to experiment with high-fat, low-carbohydrate diets during training to improve the body’s efficiency in burning fat for fuel.
Carbohydrates
Carbohydrates serve as the primary source of energy for the body and are crucial for sustained running over long distances. Upon consumption, the body converts dietary carbohydrates into glucose, which is the simplest form of sugar.
Glucose plays a crucial role as a primary energy source for humans as it is required by the body to generate adenosine triphosphate (ATP), the energy currency of cells. During physical activities like running or exercising, glucose can be rapidly supplied to muscle cells for immediate energy production. Any leftover glucose in the bloodstream is then transported to the liver and muscle cells to be stored as glycogen.
Firstly, while you’re running, your body extracts glucose from the blood to fuel the muscles in action. As the glucose levels start to decline, the body starts converting stored glycogen back into glucose via a procedure known as glycogenolysis.
Your body’s maximum oxygen usage during exercise, known as VO2max, rises alongside higher intensity exercise. This causes a decrease in available oxygen for energy generation and prompts your body to rely on anaerobic energy production, mostly fueled by carbohydrates.
As you increase the intensity of your exercise, like when you engage in shorter distance runs and sprints, your body relies on carbs primarily and fats as a secondary source of fuel. Since sprints usually last for a shorter duration, most individuals have enough blood glucose and glycogen reserves to sustain their run.
In longer runs of lower intensity, the body starts to rely more on fat stores for energy. This typically occurs in runs that exceed 6 miles (10 km). Additionally, most long-distance runners will require simple sugars to maintain their run. Hence, many of them choose to consume sports beverages or energy gel.
For most runners, it is advisable to aim for consuming approximately 45–65% of their total daily calories from carbohydrates.
Protein
Rather than being a primary fuel source in endurance exercise, protein is utilized by the body to provide support for:
- muscle growth and regrowth
- tissue repair
- injury prevention
- the production of oxygen-carrying red blood cells
- overall recovery
Refueling with protein is crucial for rebuilding the muscles that break down during running. Without protein, the muscles cannot efficiently rebuild, resulting in muscle wasting, a higher susceptibility to injury, and decreased performance.
The recommended amount of protein to consume per day varies from person to person, but most studies suggest that consuming 0.6–0.9 grams of protein per pound (1.4–2.0 grams per kg) of body weight is sufficient for recovery and can potentially prevent muscle loss in extreme endurance athletes.
Micronutrients are to be considered by thinking in a systematic manner, without adding or omitting any information.
To support the function of your body’s metabolic pathways, you’ll need a diet that is abundant in micronutrients. It is important to note that the specific needs may vary for each athlete, however, certain micronutrients hold particular significance.
- Calcium. This is a main player in bone health and muscle contraction. Most people consume enough in their diet from calcium-rich foods, including dairy products and leafy greens.
- Vitamin D. Vitamin D is important for bone health because it supports calcium and phosphorus absorption. It may also contribute to muscle metabolism and function. You can get it from sun exposure, supplements, and vitamin-D-rich foods.
- Iron. This is crucial for the development of red blood cells, which deliver oxygen to working muscle cells. Distance runners, vegetarians, and vegans may need higher than the recommended dietary intake — greater than 18 mg per day for women and 8 mg per day for men.
- Antioxidants. Antioxidants help decrease cell damage caused by oxidation from intense exercise. Consuming antioxidant-rich foods — like vegetables, fruit, nuts, seeds — seems to be more effective than taking antioxidant supplements.
- Other nutrients and aids. Many athletes may use supplements or consume foods to enhance performance, such as beetroot, caffeine, beta-alanine, and carnosine. Some of these are backed by more research than others.
If you think you might have a deficiency or want to try a new supplement, it is advisable to consult a healthcare professional since consuming a varied diet of whole foods will usually provide enough micronutrients for most people.
Pre-run nutrition
If you exercise for less than 60 minutes, it is generally safe to do so without eating first. However, it may be beneficial to consume a small snack that is high in carbohydrates to quickly acquire glucose. Some examples of suitable snacks include:
- 2–3 Medjool dates
- applesauce
- a banana
- a glass of orange juice
- energy gel
If you are planning to run for more than 60-90 minutes, it is recommended that you consume a small meal or snack containing 15-75 grams of carbohydrates at least 1-3 hours before your workout. This allows your body sufficient time to digest the food.
There are various carbs that one can consume, such as:
- a fruit smoothie made with milk and a banana
- scrambled eggs and toast
- a bagel with peanut butter
To avoid potential stomach upset during exercise, it is advisable to refrain from consuming high fiber foods such as whole grains, beans, lentils, and certain vegetables a couple of hours prior to a run. This is mainly due to their prolonged digestion process.
In conclusion, individuals who engage in running for longer than 90 minutes may consider carb loading several days prior to the event. This entails consuming a significant amount of carbohydrates before embarking on a lengthy run, with the purpose of maximizing glycogen storage in the body to provide rapid energy.
During the process of carb loading, individuals often strive to consume 3.2–4.5 grams of carbohydrates for each pound (7–10 grams per kilogram) of their body weight per day, within the 36–48 hours leading up to their run. Complex carbohydrates, including, are considered the most beneficial sources.
- potatoes
- yams
- whole wheat pasta
- brown rice
- multigrain bread
- low fiber cereals
During your run
When it comes to running, the main macronutrient you should prioritize is carbohydrates. What you eat will primarily rely on the duration and intensity of your run. Provided below are some general recommendations to consider based on different run lengths.
- Less than 45 minutes. No carbohydrate-rich food or beverage is required.
- 45–75 minutes. You might want a carbohydrate-rich mouth rinse or small sips of a sports beverage.
- 60–150 minutes. You may wish to top-off your blood sugar levels with 30–60 grams per hour of a sports beverage or energy gel.
- 150 minutes or longer. During long-distance endurance runs, you may need to replenish with upwards of 60–90 grams of carbs per hour. Most people prefer to replenish with carbohydrate-rich sports beverages, gels, chews, and bananas.
Post-run
Deciding whether to eat immediately following a run will be based on the intensity of the workout, the duration of the run, and individual preferences. If immediate eating is preferred, consider having a small snack that includes carbohydrates and protein, like chocolate milk or an energy bar.
It is recommended to consume a meal rich in carbohydrates and protein within 2 hours after your run. The goal is to intake about 20-30 grams of protein, as studies indicate that this can potentially enhance muscle protein synthesis.
Examples of foods that are rich in protein include:
- beef
- chicken
- fish
- eggs
- tofu
- beans
- lentils
- tempeh
- protein powder (whey or plant based)
To ensure your glycogen stores are refueled, consume complex carbohydrates like whole wheat pasta, potatoes, brown rice, and whole-grain bread. These foods will offer a continuous supply of glucose for several hours following your run.
The study
The study was published in the journal Frontiers in Physiology. The authors had 28 male distance runners who were competitively trained in running half-marathons, marathons, and ultras. These runners completed an incremental exercise test to exhaustion and three three-hour runs, each with a different carbohydrate-feeding protocol.
Participants consumed a diet consisting of approximately 57 percent carbohydrates, 21 percent protein, and 22 percent fat throughout the experiment.
The researchers discovered that the participants were able to attain a high level of fat oxidation despite their consumption of a mixed macronutrient diet and carbohydrates during their run, following the endurance tests.
Additionally, it was discovered that runners who consumed larger quantities of carbohydrates while running were more prone to experiencing gastrointestinal discomfort. This emphasizes the significance of regulating your carbohydrate intake during your run to enhance performance while reducing potential stomach issues.
