Before I delve into how to calculate what you need to eat, let's discuss what carbohydrate loading is and why you need to do it. (Or just jump straight to the carb loading calculator)

Carbohydrate loading is a commonly discussed area in endurance sport. But there is a lot of mystery surrounding it; should it be done and when, and if so how do you actually effectively carb load. The night before a marathon 'pasta party' has long been a tradition but to truly carbohydrate load you need to do a lot more than this, and therefore this is actually rarely effectively executed.

Questions around carb loading come up regularly when I'm helping endurance athletes create their nutrition plans. If you've got an endurance event coming up and you'd like some expert advice from a registered sports dietitian, you can book a free 15 minute call here to discuss how I can support you.

What is carbohydrate loading?

Carbohydrate loading is a strategy to optimise glycogen stores in muscles before endurance events. This is to help delay fatigue and improve performance. Our body stores glycogen in our skeletal muscles and liver, these can store around 500g and 100g respectively.

Once you use up these stores then what tends to happen is you ‘hit the wall’ or ’bonk’; something which most endurance athletes have unfortunately experienced at some point. Unsurprisingly we want to avoid this, and the best way to do this is firstly carb load, followed by fuelling during your exercise.

Not only will carb loading help you get through your event, it also help improve skeletal muscle repair and recovery after the event. These are additional benefits that are worthwhile pursuing.

Research has found that it can improve your performance by 2-3%, which may not sound a lot. But if you are aiming for a 4 hour marathon, a 2% improvement is 3hours 55mins – I don't think many people would turn down a 5 minutes improvement in their time!

It can also help delay the onset of fatigue by up to 20%.

Should I carb load for my event?

It is recommended to carb load for events that are 90 minutes or longer. It is not necessarily based on distance completed, more how long you will be exercising for. Therefore someone that is going to complete a half marathon in 90 minutes wouldn’t necessarily benefit from carbohydrate loading but someone else running it in 2 hours would benefit.

When should I start carb loading?

It is recommended that you increase your carbohydrate intake for 24-48 hours pre event and this is combined with an exercise taper (reducing down the amount of exercise pre-event and resting).

How many carbs do I need while carb loading?

The current recommendations are to have between 8-12g carbohydrate per kg of bodyweight per day.

You can use our handy carb loading calculator to calculate your minumum and maximum recommended amounts for carb loading:

Lower end and higher end carb loading examples:

Weight (in kg)	Lower end (8g/kg)	Higher end (12g/kg)
50	400g	600g
55	440g	660g
60	480g	720g
65	520g	780g
70	560g	840g
75	600g	900g
80	640g	960g
85	680g	1020g
90	720g	1080g
95	760g	1140g
100	800g	1200g
105	840g	1260g
110	880g	1300g

Disclaimer: Although these numbers are a good guide, if you want to be at peak performance for your event, it's always best to get advice from a professional sports dietitian who can help you create a plan tailored to you and your body. I offer 1:1 online appointments for endurance athletes - book a free 15 minute call here to discuss whether this is the right option for you.

Now you know the numbers, how do you actually achieve this? 

What is important to recognise is that it can be difficult to hit these high numbers, especially if you do not plan your nutrition over the couple of days. Therefore plan in advance and use the following areas to help you plan.

 Weigh yourself and work out when to start carb loading. 

• Work out your weight in kilograms and use the table above to help guide you how many grams of carbohydrates you will need.
• What day and date of your race. If you are racing on Saturday then the carb load should be on Thursday and Friday. 

Work out how many grams of carbohydrate. 

• You need between 8-12g of carbohydrates per kg body weight. Yes this is a really high amount, but it is what is needed to get the benefits! However I do find it is more achievable to aim for the 8g range. Use the carb loading calculator above to find out your recommended amount.

What are the best types of carbs for carb loading?

• Choose high glycaemic carbs.
  • This is not a time for worrying about whether you are hitting your fibre intake for the day or getting a balanced diet. Due to the high amount of carbs needed, the key is to choose the easy, high glycaemic carbs.
  • Choosing the healthier and higher fibre containing carbohydrates will be too bulky and uncomfortable to get in, in the volume needed.
• The name of the game is not to increase your overall intake, but ensure that carbs feature heavily and as the biggest proportion of your overall intake.
• Decrease down the amount of fat and protein in your diet to make way for that extra portion of rice or pasta. Think snacks, confectionary, white rice/pasta, granola, rice cakes and carb-based drinks. 

How to get enough carbs for carb loading

• Split it up over the day
  • Aim to have 5-6 carb-based meals and snacks across the day. Do not try to do this in 1 or 2 meals as it will be virtually impossible. 
  • Plan ahead to choose tasty and palatable options so you can meet your targets. 
• This is only a 2-day process, so do not worry about trying to be super healthy, remember this is to facilitate your performance on the day. You have put all the hard work in your training, so give yourself a little boost. 

Are there any cons? 

Yes, the main negatives I see are bloating and discomfort with this change in diet. People can report feeling ‘heavy’. Practicing this in your training and working out what works best for you is important. 

Weight gain will happen with a successful carb load and a lot of people can see this as a con. This happens because each gram of glycogen is stored with 3g of water. This is a totally natural response and actually should be seen as a positive that you are well fuelled and topped up with glycogen.

Example carb loading meal plan (600g carbohydrate):

Breakfast: 

Porridge (60g oats, skimmed milk, banana, honey)
2x white toast with jam. 
200ml glass orange juice

Snack:

6x Jaffa cakes. Bunch of grapes

Lunch:

Tuna mayo baguette
Low fat fruit yoghurt
200ml orange juice

Snack: 

2x crumpets with honey

Evening meal:

Chicken and vegetable noodle stir fry (170g noodles)
Tin rice pudding
200ml orange juice

Snack: 

½ pack Rice cakes
Mug of hot chocolate (made with skimmed milk)

A few top tips to leave you with:

• Practice in training and plan in advance, to truly carb load you need to plan to help hit those high numbers. 
• However any increase in carbohydrate will provide some benefit. 
• Do not worry about it being less healthy – this is a short term change to provide performance benefits.
• You may find rice based products are easier to manage in larger volume. Wheat based products including bread and pasta can cause bloating for some people. 
• Remember, carbs are king when you want to go far!

If you have an event coming up and you're unsure if you should be carb loading and how to do it, just get in touch and I can support you to ensure you are in prime form on that start line.