It can be difficult to know where to look for reliable nutrition advice when it comes to sports nutrition. It seems everyone has their own opinion on carbohydrate’s and advice is conflicting to say the least. With everyone doing something different, low carb, keto, training low and competing high, it can be challenging to know what to do for the best. If you'd like some clarity on the subject from a registered dietitian, keep on reading.
Carbohydrates
Carbohydrates (Carbs) are found in different forms such as complex carbohydrate’s (e.g. bread, pasta, rice, potato) and simple sugars (e.g. sugar, honey, syrup). They are abundant in many foods, also found in fruits, vegetables, beans and dairy products. Carbohydrates are your bodies preferred energy source, they are broken down into sugar molecules, called glycogen, to be used in all cells, muscles and tissues of the body to function. The majority of the body’s glycogen is stored in your muscles and liver. When you exercise, especially at high intensity, your body prefers to use glycogen as its primary energy source and fat as a secondary source of fuel. However, many strategies have been trialled and tested with the idea that if we reduce our carbohydrate intake, our bodies burn more fat over glycogen, and for some this sounds rather appealing.
So, should I “go low”?
How you train and how you fuel your training sessions can have a direct impact on your sport performance. Traditional approaches to managing nutrition for endurance training have strongly advised to follow a high carbohydrate diet. However, new research has emerged in recent years discovering more about the complexities of fuel and performance, showing promising results and highlighting training adaptations depending on variable nutrient intakes.
Strategies that train our muscles to use fat as the primary energy source over glycogen, essentially make an athlete more efficient at using fat as an energy source over carbohydrates whilst exercising. Multiple low-carb diets have been studied, and there have been some positive outcomes in muscle adaptions for some of these diets. Prof. John Hawley and colleagues found that ‘sleeping low’ (low carb) may exaggerate some training adaptions, however results are not consistent. The concept of “train low and compete high” is to get the best of both worlds, by deliberately reducing carbohydrate availability during training, then restoring carbohydrate availability prior to an event so that the athlete can perform at a greater intensity for longer. While ‘Training low’ can be useful depending on your goals, consistently being ‘low-carb’ is likely to hamper your ability to use carbs as a fuel source. By competition day, this may impede performance.
Interestingly, over 70% of the research in this area has produced positive outcomes in muscle adaptations, however this does not necessarily correlate to improved exercise performance. For studies specifically measuring performance outcomes, only 37% showed improvement, whilst 63% resulted in no change to performance. The conclusion is this: the quality of research is lacking and therefore we are unable to make appropriate recommendations towards the optimal use of low carb, high fat diets for athletic performance.
Should I eat Carbohydrates then?
On the flip side, research consistently shows that exercise with high carbohydrate availability improves acute exercise performance when compared to exercising in a state of low carbohydrate availability. Scientific research continues to highlight the benefits of consuming carbohydrate rich foods before, during and after intense training or competitions to ensure that muscle glycogen stores are restored. Supporting that ingesting adequate carbohydrates optimises sport performance and recovery.
It is important to note that individuals engaging in general fitness and not training for any particular sports performance goal can typically meet daily carbohydrate needs by consuming a “normal” diet. However, athletes involved in moderate or high-volume training need larger amounts of carbs (and protein) in their diet to support the increased demands.
Depending on your personal goals and interests, you may still want to limit carbohydrates and therefore it may be beneficial for you to adopt some carbohydrate periodisation strategies as part of your nutrition plan. This is to ensure you are adequately fuelled for your training and events to optimise your sport performance, recovery and reduce risk of injury. If you are altering your diet alongside a demanding training plan, I’d advise you consult a professional such as a registered dietitian or nutritionist specialising in sports nutrition to ensure you are getting the most out of your nutrition.
References
Kerksick, C.M., Wilborn, C.D., Roberts, M.D. et al. (2018) ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr 15, 38. https://doi.org/10.1186/s12970-018-0242-y
Tiller, N.B., Roberts, J.D., Beasley, L. et al. (2019) International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr 16, 50. https://doi.org/10.1186/s12970-019-0312-9
Jeukendrup, A. E. (2017) Periodized nutrition for athletes. Sports Med, 47 (Suppl 1): S51-S63.
Burke, L., & Hawley, J. (2015) Nutritional strategies to enhance fat oxidation during aerobic exercise. In Burke, L. & Deakin, V. (5th Eds), Clinical sports nutrition (pp 463 - 492). Sydney, NSW: McGraw-Hill.
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