What is Carbohydrate Loading?

The concept of carbohydrate loading is popular amongst Marathon runners and triathletes prior to competition. Carbohydrate loading is more than simply eating pasta for dinner the night before competition and certainly doesn’t mean gorging yourself with food for the entire week leading up to a race. As your training decreases leading into a race, energy (kilojoule) and carbohydrate requirements also decrease. During an easy week prior to competition it is important to taper your food intake accordingly to avoid unwanted weight gain immediately prior to racing. To adequately fill muscle glycogen (carbohydrate store in the muscle) athletes need to consume between 7-12g of carbohydrate per kilogram body weight for 24-48 hours prior to competition. The length and total amount of carbohydrate consumed by an athlete will depend largely on the distance of the race so it needs to be adjusted if competing in half marathons.

For athletes competing in Half Ironman, marathon and Ironman races, should increase their carbohydrate intake to 10-12 grams of carbohydrate per kilogram body weight for 48 hours before race start. This will allow the muscles to maximally load with glycogen prior to race start, which will help offset fatigue.

A 70kg athlete competing in a marathon should aim to consume 490-650 grams of carbohydrate on the day before a race. An example meal plan is outlined below. It is important to recognize the use of carbohydrate rich, low-fat, easily digested, low bulk foods and fluids. The essence of carbohydrate loading is to increase your carbohydrate intake, not your intake of other nutrients namely fat.

Sample carbohydrate loading plan for a 70kg Marathon runner:


  • 3 cups of low-fibre breakfast cereal with 1½ cups of reduced fat milk
  • 1 Medium Banana
  • 250ml Orange Juice


  • Toast with Honey
  • 500ml Sports Drink


  • 2 Sandwiches (4 slices of bread) - filling as desired
  • 200g tub of Low-Fat Fruit Yoghurt
  • 375ml can of Soft Drink


  • Banana Smoothie made with low-fat milk, Banana and Honey
  • Cereal Bar


  • 1 cup of Pasta Sauce with 2 cups of Cooked Pasta
  • 3 slices of Garlic Bread
  • 2 glasses of Cordial

Late snack

  • Toast and Jam 500ml Sports Drink

This sample carbohydrate loading meal plan provides roughly 14,200 kJ, 590 grams of carbohydrate, 125 grams of protein and 60 grams of fat.

Pre-Race Eating

The majority of marathons start early in the morning so there is the temptation to miss breakfast before race start. It is crucial to eat a pre-race meal in order to top up muscle and liver glycogen stores prior to race start. A pre-race meal containing roughly 2 grams of carbohydrate per kilogram body weight should be consumed roughly 2 hours before racing. The meal should contain familiar carbohydrate rich foods and fluids that are low in fat and fiber. For instance two English muffins, 1.5 tbsp of jam, 1 tsp Marmite and 750 ml sports drink provides 2500 kJ, 125 grams of carbohydrate, 2 grams of fat, 14 grams of protein and only 4 grams of fiber. Foods like liquid meal supplements, sports bars, bananas and juice are also popular pre-race meal choices.

If you have the early morning jitters liquid meal such as smoothies or Sports drinks provide an easily digested alternative to foods. It is also worthwhile to sip on water during the hour before race start to top up fluid levels.

Does Carbohydrate Loading Improve Performance?

Muscle glycogen levels are normally in the range of 100-120mmol/kg ww (wet weight). Carbohydrate loading enables muscle glycogen levels to be increased to around 150-200mmol/kg ww. This extra supply of carbohydrate has been demonstrated to improve endurance exercise, by allowing athletes to exercise at their optimal pace for a longer time. It is estimated that carbohydrate loading can improve performance over a set distance by 2-3%.

Who Should Carbohydrate Load?

Anyone exercising continuously for 90 minutes or longer is likely to benefit from carbohydrate loading. Typically, sports such as cycling, marathon running, longer distance triathlon, cross-country skiing and endurance swimming benefit from carbohydrate loading. Shorter-term exercise is unlikely to benefit as the body’s usual carbohydrate stores are adequate. Carbohydrate loading is generally not practical to achieve in team sports where games are played every 3-4 days. Although it might be argued that players in football have heavy demands on their muscle fuel stores, it would be impossible to achieve a full carbohydrate protocol within the weekly schedule of training and games.

Are There Any Special Considerations for Females?

Most studies of glycogen storage have been conducted on male athletes. However, some studies suggest that females may be less responsive to carbohydrate loading, especially during the follicular phase of the menstrual cycle. Further research needs to be conducted specifically on females.

What Are the Common Mistakes made when Carbohydrate Loading?

Research indicates that many athletes who attempt to carbohydrate load fail to achieve their goal. The method sounds simple, so what are so many athletes doing wrong? The most common mistakes are outlined below:

  • Carbohydrate loading requires an exercise taper. Athletes can find it difficult to back off and not train hard for 3-4 days before competition. Failing to rest will compromise carbohydrate loading.
  • Many athletes fail to eat enough carbohydrate. It sounds easy to increase your carbohydrate intake but many athletes fall short of the mark. It seems athletes do not have a good understanding of the amount of food required to carbohydrate load. Working with a sports dietitian or using a carbohydrate counter can be useful.
  • In order to consume the necessary amount of carbohydrate, it is necessary to cut back on fiber and make use of compact sources of carbohydrate such as sugar, cordial, soft drink, sports drink, jam, honey, jelly and tinned fruit. Athletes who include too many high fiber foods in their carbohydrate loading menu may suffer stomach upset or find the food too bulky to consume.
  • Carbohydrate loading will most likely cause body mass to increase by approximately 2kg. This extra weight is due to extra muscle glycogen and water. For some athletes, a fear of weight gain may prevent them from carbohydrate loading adequately.
  • Athletes commonly use carbohydrate loading as an excuse to eat everything and anything in sight. Consuming too many high fat foods will make it difficult to consume sufficient carbohydrate. It may also result in gain of body fat. It is important to stick to high-carbohydrate; low-fat foods while carbohydrate loading.

Each of the selections provides approximately 50 grams of carbohydrate:

Ralph Hydes www.ralph-hydes.com

  • Sports foods

    • Sports drink 700 m
    • Carbohydrate loader supplement 250 m
    • Liquid meal supplement 250-300 m
    • Sports bar 1-1.5 bar
    • Sports gels 2 sachets

  • Drinks

    • Fruit juice - unsweetened 600 ml Fruit juice - sweetened 500 ml
    • Cordial 800 ml
    • Soft drinks and flavored mineral water 500 ml
    • Fruit smoothie 250-300 ml

  • Sugars and confectionery

    • Sugar (50 g)
    • Jam (3 Tbsp)
    • Syrups (4 Tbsp)
    • Honey (3 Tbsp)
    • Jelly babies (60 g)

  • Dairy Products

    • Milk 1 litre
    • Flavoured milk 560 ml
    • Custard 300 g (1.3 cup or half 600 g carton ready made)
    • ‘Diet’ yoghurt and natural yoghurt 800 g (4 individual tubs) Flavoured non-fat yoghurt 350 g (2 individual tubs)
    • Fromage Frais 400 g (2 tubs)
    • Rice pudding/creamed rice 300g (1.5 cups)

  • Vegetables

    • Potatoes 350 g (1 very large or 3 medium)
    • Sweet potato 350 g (2.5 cups)
    • Corn 300 g (1.2 cups creamed corn or 2 cobs)
    • Green Beans 1,800 g (14 cups)
    • Baked beans 440 g (1 large can)
    • Lentils 400 g (2 cups)
    • Soy beans and kidney beans 400 g (2 cups)
    • Tomato purée 1 litre (4 cups)
    • Pumpkin and peas 700 g (5 cups)

  • Fruit

    • Fruit crumble 1 cup
    • Fruit packed in heavy syrup 280 g (1.3 cups) Fruit stewed/canned in light syrup 520 g (2 cups)
    • Fresh fruit salad 500 g (2.5 cups)
    • Bananas 2 medium-large
    • Mangoes, pears, grapefruit and other large fruit 2-3 Oranges, apples and other medium size fruit 3-4
    • Nectarines, apricots and other small fruit 12
    • Grapes 350 g (2 cups)
    • Melon 1,000 g (6 cups)
    • Strawberries 1,800 g (12 cups) Sultanas and raisins 70 g (4 Tbsp)
    • Dried apricots 115 g (22 halves)

  • Cereals

    • Wheat biscuit cereal (e.g. Weetabix) 60g (5 biscuits)
    • ‘Light’ breakfast cereal (e.g. Cornflakes) 60 g (2 cups)
    • ‘Muesli’ flake breakfast cereal 65 g (1-1.5 cups)
    • Porridge - made with milk 350 g (1.3 cups)
    • Porridge - made with water 550 g (2.5 cups)
    • Rolled oats 90 g (1 cup)
    • Muesli bar 2.5
    • Rice cakes 6 thick or 10 thin
    • Pasta or noodles, boiled 200 g (1.3 cups)
    • Canned spaghetti 440 g (large can)
    • Crisp breads and dry biscuits 6 large or 15 small
    • Fruit filled biscuits 5
    • Plain sweet biscuits 8-10
    • Bread 110 g (4 slices white or 3 thick wholegrain)
    • Bread rolls 110 g (1 large or 2 medium)
    • Pita and Lebanese bread 100 g (2 pita)
    • Chapatti 150 g (2.5)
    • English muffin 120 g (2 full muffins)
    • Crumpet 2.5
    • Pancakes 150 g (2 medium) Scones 125 g (3 medium)
    • Iced fruit bun 105 g (1.5)
    • Rice-cream 300 g (1.5 cups)

Eating before Exercise

Many athletes put a lot of emphasis on the pre-event meal believing it is the key element to performance. It is important to remember that food eaten throughout the training week and food and fluid consumed during the event is also important. The meal eaten before exercise should be seen as an opportunity to fine-tune carbohydrate and fluid levels and to ensure you feel comfortable and confident.

When Should I Eat?

Food consumed before exercise is only useful once it has been digested and absorbed. This means you need to time your food intake so that the fuel becomes available during the exercise period. The time required for digestion depends on the type and quantity of food consumed. Generally, foods high in fat, protein and fiber tend to take longer to digest than other foods, and may increase the risk of stomach discomfort during the event. Large quantities of foods take longer to digest than smaller quantities. You need to experiment to find the timing that best suits your individual needs. Generally, athletes in sports involving lower intensity activity, or sports where the body is supported (e.g. swimming, cycling) are able to tolerate more food in the gut than sports such as running where the gut is jostled about during exercise. A general guide is to have a meal about 3-4 hours before exercise or a lighter snack about 1-2 hours before exercise.

What Should I Eat?

Food eaten before exercise should provide a good source of carbohydrate. It should also be low in fat and moderate in fiber to aid digestion and reduce the risk of gastrointestinal discomfort or upsets. On occasions, it may be important to place emphasis pre-event on intake of carbohydrate and fluid. However, it is also useful to continue to consider other nutritional goals when choosing a pre-exercise meal. This means opting for meals that provide a wide variety of nutrients including protein, vitamins and minerals.

The following foods are suitable to eat 3-4 hours before exercise:

crumpets with jam or honey + flavoured milk

baked potato + cottage cheese filling + glass of milk

baked beans on toast

breakfast cereal with milk

bread roll with cheese/meat filling + banana fruit salad with fruit-flavoured yoghurt

pasta or rice with a sauce based on low-fat ingredients (e.g. tomato, vegetables, lean meat)

The following snacks are suitable to eat 1-2 hours before exercise:

liquid meal supplement milk shake or fruit smoothie

sports bars (check labels for carbohydrate and protein content) breakfast cereal with milk cereal bars

fruit-flavoured yoghurt fruit

The following foods are suitable to eat if there is less than 1 hour before exercise*:

sports drink

carbohydrate gel cordial

sports bars jelly babies

* A small number of people experience an extreme reaction following the intake of carbohydrate in the hour prior to exercise.