Cancer Care. Health Screening. Laboratory Services. Parkway Cancer Centre. Rehabilitation Services. Urgent Care Centre. Browse Topics From A-Z. About Health Plus. Gleneagles Hospital. Words of Appreciation. Carb loading is a dietary approach used by athletes that involves consuming a high-carbohydrate diet, usually 1 — 3 days prior to a long-duration endurance event to increase glycogen stores in their muscles as part of the preparation process.

Such events include marathons, long-distance road cycling, long-distance swimming, or if athletes are playing a tournament with back-to-back games, such as during basketball championships or soccer tournaments.

Modifying diet and exercise routines aims to create a larger "fuel tank" of stored muscle glycogen, our body's preferred energy source during prolonged, high-intensity activity.

Carbohydrates, often referred to as carbs, are one of the primary macronutrients, alongside proteins and fats, vital to our bodily functions. They are the body's main energy source, supplying the energy that our cells require to carry out their daily functions. Carbohydrates are made up of small molecules of sugars, or saccharides, that when combined in various ways form different types of carbohydrates.

Based on their structure and complexity, carbohydrates can be divided into 3 main types. Simple carbohydrates sugars. Simple carbohydrates, also known as sugars, consist of one or 2 saccharides — monosaccharides or disaccharides.

Examples of sugars include glucose, sucrose, and fructose. They are quickly absorbed and provide a rapid source of energy. Sugars are found naturally in fruits, milk and milk products, and simple sugars are also added to a variety of processed foods and drinks like sweets and soft drinks.

Complex carbohydrates starches. Complex carbohydrates, or starches, consist of many saccharide units linked together and are found in foods such as potatoes, bread, rice, and pasta. These carbohydrates are digested more slowly than simple sugars, providing a more sustained energy release due to their lower glycaemic index.

This is particularly true of starches that contain fibre e. wholemeal bread, potatoes with skin, and brown rice. Dietary fibre. Dietary fibre is a type of carbohydrate that our bodies cannot digest.

There are 2 types of fibre: soluble, which dissolves in water and can help lower blood glucose and cholesterol levels, and insoluble, which can help food move through your digestive system, promoting regularity and helping prevent constipation. It is important to understand the different types of carbohydrates and their roles to better optimise dietary strategies such as carb loading, to improve athletic performance.

Carb loading is primarily intended for endurance athletes preparing for prolonged, intensive events, typically those lasting 90 minutes or longer. This is because such strenuous activities deplete glycogen stores in muscles, which could result in fatigue and reduced performance.

By carb loading, athletes aim to maximise their glycogen storage, which can enhance their endurance and delay the onset of fatigue. Examples of activities where carb loading may be beneficial include marathon running, long-distance cycling, triathlon events, and long-distance swimming.

However, it's less relevant for sports involving short bursts of activity, such as sprinting or weightlifting, and for activities of a lower intensity or shorter duration.

While carb loading can be beneficial for endurance athletes, it's important to note that it should be approached with care. Not every endurance athlete will respond to carb loading in the same way, and individual dietary needs can vary widely.

Carb loading primarily benefits athletes by enhancing their endurance. By maximising muscle glycogen, the body's preferred form of carbohydrate during exercise, athletes can maintain a high level of exertion for longer periods during endurance events, thus delaying the onset of fatigue.

Consuming glycogen after exercise helps replace muscle glycogen depleted during exercise, and aids in storing more glycogen as an adaptation to training. This is especially beneficial when events are spaced closely together — generally, if events are less than 8 hours apart.

The importance of carbohydrates extends beyond physical performance to mental acuity as well. Sufficient carbohydrate intake fuels the brain, aiding in maintaining focus and decision-making during endurance events. Research suggests that consuming a high carbohydrate intake prior to a long-duration endurance event may delay the onset of fatigue and reduce risk of injury, further boosting the athlete's capacity for sustained performance.

However, carb loading strategies should be personalised, as individual needs and responses can vary greatly. Timing is crucial when it comes to carb loading. Begin the process approximately 36 — 48 hours prior to your event. This timeframe allows your body to store glycogen, the primary fuel source during prolonged exercise.

To determine the right amount of carbohydrates to consume, it's advisable to consult with a sports dietitian. They can assess your individual needs and recommend a specific daily intake.

Generally, athletes are advised to consume around 8 — 12 grams of carbohydrates per kilogram of body weight per day during the carb loading phase. In conjunction with increased carbohydrate consumption, it's important to implement an exercise taper during this period.

Reducing the intensity and volume of your workouts allows your muscles to recover and glycogen stores to be maximised.

A useful tip would be to practise carb loading as part of training prior to the actual competition or event. This will allow you to experiment with different strategies, gauge their effectiveness, and make any necessary adjustments. By doing so, you can optimise your performance and fuel your body effectively for the endurance challenge ahead.

It's important to note that carb loading protocols may vary among athletes. To develop a personalised plan, it is recommended to discuss your specific needs with both a sports dietitian and physical trainer. They can guide you through the process, fine-tuning the dietary and training aspects to suit your individual requirements.

Carb loading doesn't mean you should increase your total daily calories. Rather, it involves adjusting the proportion of your calorie intake that comes from carbohydrates. Overeating can lead to weight gain and feelings of heaviness or discomfort, which are not conducive to optimal performance.

Do not neglect to consume sufficient fluids prior to an endurance event to ensure that you are adequately hydrated. Failing to properly hydrate can lead to dehydration and negatively impact your performance and recovery. Another common mistake is not consuming enough carbohydrates to maximise glycogen stores.

For effective carb loading, aim for 8 — 12 grams of carbs per kilogram of body weight each day. The exact amount of carbohydrates required prior to an event should be discussed with a sports dietitian, as this will vary across different individuals and different types of sport.

This can come in the form of refined carbohydrates like bread, rice, and noodles. Although foods and drinks high in refined sugars, such as smoothies, cereal bars, and flavoured milks are generally not recommended on a regular basis, it is acceptable to use these foods and drinks to meet the higher-carbohydrate demands of carb-loading prior to endurance events.

Some athletes consume too much fibre while carb loading, leading to gastrointestinal discomfort. In the final days leading up to the event, switching to low-fibre carbohydrate sources such as white bread instead of wholemeal bread, or regular pasta rather than wholegrain pasta can help alleviate potential digestive issues.

Some people make the mistake of consuming high-fibre or fatty foods during their carb loading phase. Fatty foods can displace the carbs needed to fill glycogen stores, and while high -fibre foods like vegetables, whole grains and fruit are healthy and recommended on a regular basis, these should not be overconsumed during the carb loading phase because they can cause digestive discomfort especially if consumed in large amounts.

While the focus of carb loading is on carbohydrates, protein should not be completely overlooked. Including a moderate amount of protein in your meals can aid in muscle repair and recovery.

Speak to a sports dietitian to understand your individual protein needs and how adequate protein can be incorporated into a high-carbohydrate diet. The days leading up to a race are not the time to try a new dietary strategy. Every athlete is unique, and you should use your periods of training to trial and fine-tune your carb loading plan.

When carb loading, you should avoid high-fat and high-fibre foods and alcohol. Instead, what you should go for are foods that are high in carbohydrates and low in fibre to maximise glycogen storage and minimise digestive discomfort.

These include:. Refined grains. Choose white bread, white rice, or pasta. While whole grains are generally healthier, they're higher in fibre, which can lead to digestive discomfort when consumed in large quantities. Refined grains, on the other hand, are more easily digested, and are therefore more appropriate to meet the high carb needs during carb loading.

Starchy vegetables. Potatoes and sweet potatoes without skin, as well as taro are some good choices. Fruit juices and canned fruits. These are high in simple sugars which are more carbohydrate-dense than fresh fruit.

It is acceptable to include foods and drinks high in refined sugars, such as juices, flavoured milk, canned fruit, and smoothies as part of the diet to meet the high carb needs during the carb loading phase.

Low-fat dairy. Milk, yogurt, and low-fat cheeses provide carbohydrates along with some protein for muscle recovery. Flavoured low-fat milks and yoghurt are a good way to provide lots of carbohydrates in a small volume.

If you're interested in learning more about carb loading or are going to go on the diet for an upcoming event, our experienced dietitians can help. This is a phenomenon that has been rearing its head much more in recent years. Using a random crossover design, 8 trained runners completed a min submaximal run and a performance run to exhaustion after two dietary treatments.

The mixed diet MD contained 4. d-1 of carbohydrate CHO for 6 days. The experimental diet HCD contained 4. d-1 for 3 days followed by 8. d-1 for 3 days. Day 6 was a rest day, and testing was completed on Day 7.

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J Appl Physiol ; — Heigenhauser GJF, Sutton JR, Jones NL. Effect of glycogen depletion on the ventilatory response to exercise. J Appl Physiol ; —4. Bosch AN, Dennis SC, Noakes TD. Influence of carbohydrate loading on fuel substrate turnover and oxidation during prolonged exercise.

J Appl Physiol ; —7. Energy metabolism and prolonged exercise. In: Lamb DR, Murray R, editors. Perspectives in exercise science and sports medicine. Volume 1: prolonged exercise. Indianapolis: Benchmark Press Inc. Hawley JA, Hopkins WG. Aerobic glycolytic and aerobic lipolytic power systems. A new paradigm with implications for endurance and ultraendurance events.

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No effect of glycogen level on glycogen metabolism during high intensity exercise. Maughan RJ, Poole DC. The effects of a glycogen-loading regimen on the capacity to perform anaerobic exercise. Eur J Appl Physiol ; —9. Greenhaff PL, Gleeson M, Maughan RJ.

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Download references. Sports Science Institute of South Africa, incorporating the Liberty Life Chair of Exercise and Sports Science, the Medical Research Council and the University of Cape Town Bioenergetics of Exercise Research Unit, Department of Physiology, University of Cape Town Medical School, Cape Town, South Africa.

John A. Hawley PhD, Elske J. Schabort, Timothy D. You can also search for this author in PubMed Google Scholar. Correspondence to John A. This would be about grams of carbs if you weighed pounds 70 kg. You do not exercise for one day, and you consume a high-carb diet of about 4.

Summary There are several specific carb loading programs. The major differences between them are their durations and the amounts of exercise they include. All programs use a short-term high-carb diet while temporarily decreasing exercise. Before you start a carb-loading program, there are several common carb-loading mistakes you should be aware of.

Research has found it can be beneficial for exercise lasting more than 90 minutes 3. However, there may be no benefit for slightly shorter durations of exercise, including events lasting 60—90 minutes 7 , 8. Some research found that carb loading with 3 grams per pound 6. Other studies showed that carb loading did not improve performance during high-intensity cycling lasting less than 20 minutes 14 , While fat can be part of a balanced diet , it may be beneficial to limit how much of it you eat during carb loading Eating too much could cause weight gain or leave you feeling sluggish.

Some people make the mistake of choosing foods that are high in both carbohydrates and fat, rather than just carbs. For example, many desserts such as chocolate, ice cream and cookies fall into this category, as well as creamy pasta sauces and buttery breads.

Checking the nutrition information of foods you eat can help. Eating high-fiber foods could also be detrimental. Although fiber is part of a healthy diet , too much fiber during carb loading can cause stomach discomfort in some individuals Carb loading is a unique time when it could be better to choose white bread or pasta over whole wheat.

During this time, you should probably also avoid high-fiber foods like beans. Overall, it may be best to choose lower-fiber carbohydrate sources to avoid the possibility of fullness or stomach discomfort during exercise.

Another possible mistake is not knowing if you are eating the right amount of carbohydrates. Without recording what you eat, you may be eating too much or too little.

Experts often recommend that people who are carb loading eat 2. Recording your food intake can help you make sure you are eating the right amount 3. However, if you eat more carbs than necessary, you may have changed your diet too much or simply eaten too many calories.

As your experience grows, you may not need to do this anymore. However, it is a good idea for beginners. The days before your event or competition are important, and having an upset stomach due to unfamiliar foods can spoil your experience and exercise performance.

Because of this, you should choose foods that are familiar to you — in addition to being high-carb, low-fat and low-fiber. If you are considering using carb loading before an upcoming competition or athletic event, there are a few things you should think about.

Before you launch into carb loading, consider whether the type and duration of exercise you are doing requires it. If you will be performing exercise lasting more than 90 minutes without breaks, such as running or cycling, you may benefit from this nutrition strategy.

If your exercise is shorter or involves many breaks, such as weight training, carb loading is probably not necessary. If you record all the food you eat for several days using a food-tracking app or the nutrition labels on your food, you can calculate your current daily carbohydrate intake.

Then you can divide the grams of carbs you eat each day by your weight to compare your current intake to carb loading recommendations. For example, if you weigh pounds 70 kg and you normally eat grams of carbs per day, then you are consuming 1. People who are carb loading may eat 2. That said, experts often recommend a more limited range of 3.

Based on these recommendations, you would need to eat approximately double the amount of carbs you would normally. Avoid choosing foods that are high in both carbs and fats, such as desserts, pasta with creamy sauce, pastries and similar items.

As discussed, carb loading programs can last from one to six days. It may be a good idea to start with a simple program lasting between one and three days. For example, you could simply increase your carb intake to around 3. You could also practice several different types of carb loading during training and keep notes to decide which helped you feel and perform your best.

Generally, it is best to experiment during your training rather than right before a real competition. That way, you can decide what will work best before your big event. Lastly, it may be best to focus on familiar foods during carb loading.

Unusual foods could upset your stomach and impair your performance. Commonly recommended foods include pasta, bread, fruits and fruit juices, smoothies, cereals and other high-carb, low-fat foods. Once you have your nutrition plan set, you need to remember to taper your exercise in the days leading up to your event or competition.

Summary Before you start carb loading, consider whether you will benefit from it. You should also figure out how many carbs you normally eat so you know how much to change your regular diet.

Deciding the right duration for carb loading is also important. Of course, it is also important to have protein to support your muscles. Try to focus on lean protein sources, such as fish, lean cuts of meat or poultry and fat-free dairy. Try to find the best compromise between the recommendations and foods you enjoy.

Many people eat high-carb foods that are high-fat too. It is best to avoid these during carb loading. Below are some examples of foods that may seem high-carb but are also high-fat and therefore inappropriate for carb loading. Also, many foods that are a great part of your normal diet may be high in fiber.

You should limit or remove these foods from your diet during carb loading. These lists are not comprehensive. To find the best high-carb options for your diet, check the nutrition information for the foods you normally eat.

Summary During carb loading, you should focus on eating high-carb, low-fat and low-fiber foods that are familiar and enjoyable. Using the lists above can get you started, but you should also review the nutrition facts for your favorite foods. Carb loading involves two major components: increasing the carbs you eat and decreasing the amount you exercise.

Carb intake can range from 2. This strategy may not be useful for you if you are recreationally active but not an athlete or competitor in long-duration events. When you carb load, it may be best to choose familiar foods that are high-carb and low-fat.

You may also need to limit your fiber intake during these days. If you perform long-duration exercise, you may want to experiment with carb loading before your next event to see if it can boost your performance. Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.