Low Carb Diets For Athletes… And Other Lies

The popularity of low-carbohydrate diets has surged in recent years, with many athletes and fitness enthusiasts touting their benefits for performance and body composition. However, the scientific evidence paints a more nuanced picture, and the claims of low-carb diets being a panacea for athletes may be more myth than reality.

Importance of Carbohydrates For Athletic Performance

Carbs Are Important For Proper Fuelling

Firstly, it is important to understand that carbohydrates are the primary fuel source for moderate-to-high-intensity exercise. The body relies on carbohydrates to provide quick energy during physical activity, particularly when engaging in anaerobic or high-intensity training. Carbohydrate-rich foods help replenish muscle glycogen, which is important for optimal performance. Muscle glycogen stores become depleted during strenuous exercise, and without adequate carbohydrate intake, athletes may experience fatigue, subpar performance and the feeling of “hitting the wall” once the glycogen stores empty.

Carbohydrates are also necessary for adequate brain function, this includes concentration and quick decision-making, which may be necessary in sports where a single split-second mistake could be the difference between first place, and not qualifying at all.

Using Fat as Fuel Is Possible For Low-Intensity Exercise

Restricting carbohydrates can impair exercise capacity and performance because when glycogen stores are low, the body struggles to sustain high-intensity efforts. During high-intensity workouts, such as sprinting or weightlifting, the body primarily uses glucose derived from carbohydrates for energy. In contrast, during lower-intensity endurance activities like walking, fat becomes a more significant fuel source, suggesting that low-carb diets may be better suited for endurance activities at a lower intensity.

This finding raises important considerations for athletes who prioritize high-performance training and competition. For those individuals, a balanced intake of carbohydrates is essential to maintain energy levels and support recovery. Recovery, in particular, is where carbohydrate intake plays a role. Post-exercise carbohydrate consumption aids in glycogen replenishment, facilitating recovery and preparation for subsequent training sessions or competitions.

Lower-Carb Diets Can Be Suitable In Few Situations

While low-carbohydrate diets may have their place in specific contexts, particularly for recreational athletes or those engaged in low-intensity exercise, the evidence suggesting that they enhance performance for high-intensity athletes is limited. A careful assessment of one’s training goals, exercise intensity, and individual responses to carbohydrate intake is essential for optimizing performance and health. Consideration of the specific fuel demands of different types of exercise will support athletes in making informed dietary choices that align with their performance goals.

Adhering To A Low-Carb Diet Can Be Challenging

Restrictive Low-Carb Diets May Feel Too Restrictive

The challenges of adhering to low-carb diets extend beyond initial dietary preferences and can significantly impact overall nutrition and performance, particularly for athletes with high energy demands.

As highlighted in the study by Wrzosek et al. (2021), participants in low-carb diets frequently encountered difficulties in maintaining strict adherence. This often resulted in deviations from the prescribed dietary regimen. When carbohydrate intake is restricted, individuals may experience increased hunger, fatigue, and decreased energy levels, prompting them to consume larger meals or revert to higher-carb options. This not only compromises the intended caloric deficit but also affects micronutrient intake, which can be particularly detrimental for athletes requiring diverse nutrients for recovery and performance.

Restrictive Low-Carb Diets May Make You Feel Isolated

The social aspect of eating can pose additional challenges. Many communal meals and social gatherings center around carbohydrate-rich foods, making it harder for those on low-carb diets to navigate social situations without feeling isolated or deprived. This can lead to feelings of frustration and ultimately impact an individual’s motivation to sustain the diet long-term.

Restrictive Low-Carb Dieting Harms Your Mental Health

Psychological factors also play a critical role in adherence. Dieting can induce stress or anxiety, particularly if one feels they are constantly battling cravings or the temptation of more palatable, carbohydrate-rich foods. Over time, this mental strain can contribute to a mindset that is not conducive to long-term dietary change, leading individuals to abandon their low-carb commitments in favour of more balanced or traditionally accepted dietary patterns.

In light of these challenges, it is essential for individuals considering a low-carb diet, especially athletes, to engage in careful planning that includes not just nutritional strategies but also psychological and social support systems. Addressing these elements can enhance adherence, empowering individuals to achieve their health and performance goals while also enjoying a sustainable eating pattern.

Nuanced Applications of Low-Carb Diets for Athletes

Low-Carb Days Can Be Included In A Carbohydrate Periodization Plan

While low-carbohydrate diets are often discussed in the context of weight management and metabolic health, their applications within the realm of athletic performance are increasingly being explored. One such application is the concept of "carbohydrate periodization." This approach involves strategically manipulating carbohydrate intake relative to training and competition needs to optimize performance and metabolic adaptations.

Carbohydrate periodization typically operates on the premise that by limiting carbohydrate availability during certain training phases, athletes can induce specific metabolic adaptations that may enhance fat oxidation and improve endurance performance during prolonged activities. For instance, an athlete might choose to train in a low-carb state to facilitate the body's ability to utilize fat as a primary fuel source. This adaptation can be particularly beneficial for endurance athletes who rely on sustained energy levels over extended periods.

Do Not Expect High-Quality Training Sessions On Low-Carb Days

However, employing carbohydrate periodization effectively requires meticulous planning and a keen understanding of an athlete's unique physiology and training demands. It's essential to consider factors such as training intensity, duration, and individual metabolic responses. For example, high-intensity training sessions often necessitate greater carbohydrate availability to support optimal performance and recovery. Therefore, athletes must carefully time their carbohydrate intake, ensuring they consume adequate quantities before and after these workouts.

Flexible Nutrition Approaches Are Better For Athletes

It's important to recognize that a low-carb approach isn't universally effective for every athlete, even if you have a periodized nutrition plan. Individual responses to dietary changes can vary significantly, influenced by genetics, training status, and the specific demands of the sport. Consequently, what works for one athlete may not be suitable for another. Some claim to thrive on a low-carb regimen, while others may experience declines in performance or energy levels.

Incorporating a flexible approach while maintaining the core principles of carbohydrate periodization can serve as a beneficial strategy. This might involve alternating between low-carb and higher-carb days, matching carbohydrate intake with training loads. Such a strategy not only supports metabolic flexibility but also ensures that athletes maintain their performance across different phases of training.

You Always Need To Adapt Your Nutrition To Your Training Plan

While low-carb diets can provide nuanced applications for athletes when integrated with principles like carbohydrate periodization, they must be tailored to individual needs and training goals. Attention to an athlete's unique demands and consistent monitoring can help maximize the benefits of this dietary strategy while minimizing risks associated with inadequate energy intake.

Low-Carb Diets For Other Niche Populations

Insulin Resistance

Low-carbohydrate diets, often characterized by reduced intake of sugars and starches, have gained attention for their potential benefits among specific populations. Among these groups, individuals with insulin resistance and metabolic syndrome stand out, as emerging research indicates that low-carb diets may play a role in improving metabolic health and managing symptoms associated with these conditions.

Insulin resistance, a state where the body's cells become less responsive to insulin, often precedes the development of type 2 diabetes. Individuals with insulin resistance frequently struggle with weight management, elevated blood sugar levels, and dysregulated lipid profiles. Studies, such as those conducted by Gadgil et al. (2013) and Noakes & Windt (2017), have shown that low-carb dietary approaches can lead to significant reductions in fasting insulin levels, improved glycemic control, and beneficial changes in body composition. By decreasing carbohydrate intake, individuals may experience a shift in their metabolism, enhancing fat oxidation and promoting weight loss, which are critical factors in restoring insulin sensitivity.

Metabolic Syndrome

Similarly, metabolic syndrome—a cluster of conditions that increase the risk of heart disease, stroke, and diabetes—can potentially benefit from dietary adjustments. The hallmark features of metabolic syndrome include abdominal obesity, hypertension, elevated blood glucose, and dyslipidemia. Lower-carb diets can help mitigate these risks by promoting a decrease in visceral fat, lowering triglyceride levels, and raising high-density lipoprotein (HDL) cholesterol. These physiological changes contribute to a reduced disease risk for affected individuals.

Everyone Is Different And Nutrition Needs To Be Individualized 

However, it is essential to note that the applicability of low-carb diets is not universally beneficial for all populations. Healthy, active individuals may not experience the same advantages and should be cautious about excessive carbohydrate restriction. Active individuals may require a balanced intake of carbohydrates to support energy needs, optimize performance, and maintain overall health.

Conclusion

Carbohydrates Remain the Primary Fuel for Athletes

The claims of low-carb diets being a panacea for athletes are largely unfounded. While there may be some specific applications, the overwhelming evidence suggests that carbohydrates remain the primary fuel source for high-intensity and high-quality exercise and that restrictive low-carb diets can impair performance and be challenging to adhere to.

As with any dietary approach, athletes should work closely with qualified professionals to develop a personalized nutrition plan that supports their training and performance goals.

Hope this helped! 

Maria Tanielian
Registered Dietitian/Nutritionniste
IOC Diploma in Sports Nutrition
ODNQ # 7223, CDBC # 2815, SDA # 949, CDO #16856

References worth reading with an open mind

Fernandes, H. (2022). "the basics of carbohydrate periodization for athletes and coaches". Biomedical Journal of Scientific & Technical Research, 42(4). https://doi.org/10.26717/bjstr.2022.42.006789

Gadgil, M., Appel, L., Yeung, E., Anderson, C., Sacks, F., & Miller, E. (2013). The effects of carbohydrate, unsaturated fat, and protein intake on measures of insulin sensitivity. Diabetes Care, 36(5), 1132-1137. https://doi.org/10.2337/dc12-0869

Hearris, M., Hammond, K., Fell, J., & Morton, J. (2018). Regulation of muscle glycogen metabolism during exercise: implications for endurance performance and training adaptations. Nutrients, 10(3), 298. https://doi.org/10.3390/nu10030298

Noakes, T. and Windt, J. (2017). Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. British Journal of Sports Medicine, 51(2), 133-139. https://doi.org/10.1136/bjsports-2016-096491

Volek, J., Freidenreich, D., Sáenz, C., Kunces, L., Creighton, B., Bartley, J., … & Phinney, S. (2016). Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, 65(3), 100-110. https://doi.org/10.1016/j.metabol.2015.10.028

Wrzosek, M., Woźniak, J., & Włodarek, D. (2021). The effect of high‐fat versus high‐carb diet on body composition in strength‐trained males. Food Science & Nutrition, 9(5), 2541-2548. https://doi.org/10.1002/fsn3.2204

Keywords: Low-carb diets for athletes · Carbohydrate periodization · Low-carb diet benefits · Insulin Resistance · Metabolic Syndrome · Carbohydrate Adaptation · Fat Adaptation · Nutrition Periodization For Athletes