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Carbohydrates are a fundamental source of fuel for your body when you exercise. During exercise, our body’s will utilise carbohydrates and fats to produce energy. Higher intensity exercise uses up more carbohydrates, while less intense activity uses up more fats.  

Carbohydrate loading is a nutritional strategy used to help improve physical performance. It is a strategy commonly used by competitive athletes and involves adjusting your diet and activity levels to boost the amount of carbs in your body in the run up to an event. 

However, like with any finely tuned nutritional and/or performance strategy, mistakes are often made and this can result in an overconsumption of calories or side effects that actually hinder performance. 

This article will discuss the core benefits of carb loading, tips on how to do it effectively and potential side effects. 


What is carb loading? 

Carb loading is a strategy in which you try to increase the amount of carbohydrates stored in your muscles as glycogen.  

This is achieved by increasing carbohydrate intake while simultaneously scaling back on training load in the run up to your event. Essentially, you are increasing the amount of carbs in your body while decreasing the amount of carbs used for energy. This creates a surplus of carbs leftover which the body can utilise on the day of your race or event. 

Carb loading is primarily used by endurance athletes, as the body needs a lot of fuel to keep going over a long period of time. Events between 60-90 minutes or lower do not need carb loading, but for longer events, the body needs an extra amount of fuel to stave off fatigue and perform at a high level for an extended period of time.  

Research shows that carb loading may improve athletic performance and reduce fatigue by 2-3% for activities longer than 90 minutes, which is a considerable amount in relation to competitive sports.  

Most people will have enough energy stored to fuel 90-120 minutes of exercise, but further than this, it is advisable to consider supplementation to help maintain blood glucose levels and prevent fatigue.  


Carbohydrate loading plan 

A carbohydrate loading plan goes hand-in-hand with a training plan, as you will need to adjust the amount of physical training you are doing in line with your carb intake. 

A typical 6 week training plan will include exercises at different intensities each week and each day. The plan will include recovery days plus high intensity workouts, so your carb loading plan will need to reflect this. The load placed on your body will determine how much carbohydrate and fat it needs to fuel each training day, as well as covering your fueling needs for the following day’s training.  

Here is a graphic showing general guidance with regards to carb loading: 


Pre exercise supplementation 

Days leading up to the event 

This is where you will aim to maximise your body’s carbohydrate stores, which will be of most benefit for events longer than 2 hours. You should aim to consume 8-10kg per kg of body weight per day. As an example, an athlete weighing in at 70kg should aim to consume 700g of carbohydrate per day. 

You can also supplement with performance nitrates alongside your carbohydrate load in the days before the event to improve muscle efficiency by reducing the oxygen cost of exercise. 


Morning of the event  

In the 3-5 hours before your event, you will be aiming to top up the carbohydrate stores in your liver. Eat a breakfast meal packed with the right nutrients to do so. Examples might be bread and jam, honey, cereals, porridge or bananas. 


30-60 minutes before the event 

Consume your final top up in the form of an energy gel or gummy bar around 30 minutes before your event starts. 


Supplementation during the event 

For events longer than 2.5h aim to consume 80-120g carbohydrate per hour. This needs to be practiced in training as the gut needs to be ‘trained’ and adapt to handling high amounts of carbohydrate while exercising. 


Here is an example of how this can be achieved for a 3 hour ride with the SIS Beta Fuel range 


Post exercise supplementation 

 After your event, it’s all about recovering properly. Providing your body with both protein and carbohydrate will aid muscle recovery whilst also replenishing your carbohydrate stores. REGO powders are made to deliver the post event nutrients you need, to ensure you give your body the best chance of full recovery. 


 Potential side effects of carbohydrate loading 

 A targeted carbohydrate loading plan is different to eating a natural, balanced diet that happens to contain carbohydrates. While carb loading should be safe for most endurance athletes, there are a few potential side effects to make note of. 


  1. Diabetes – if you have diabetes, it is advisable to consult your physician before committing to a carb loading plan. Increasing your carb intake may result in a blood glucose level spike, so it is important that you understand the risks and get professional advice before carb loading. 
  2. Bloating and/or digestive discomfort – foods that are very high in carbohydrates often contain a significant amount of dietary fibre. Fibre is an important part of a healthy, balanced diet, but we can overdo it. So choose lower fibre types of carbohydrate such as white rice, breads and low fibre cereals whilst reducing vegetables, pulses and nuts if this is something that you experience. 
  3. Weight gain – carb loading is not a strategy recommended for use alongside day-to-day workouts or casual sports, as you could end up putting on weight. The amount of energy needed for endurance events means that those excess carb calories burn away, but without this type of intensive output, you may go into a calorie surplus and gain weight. 
Written By

Jessica Redman - Head Coach and Founder of Work That, Trustee at CIMSPA

Jessica founded an online personal training platform called ‘Work That’ and was previously Co-founder of ‘GRL GYM’. She is currently on the CIMSPA board where she is aiming to help drive forward knowledge about the benefits exercise has on mental health. Jess believes in using exercise to help people feel good, relive pain and enjoy an active lifestyle.