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We investigated how a ketogenic diet affects load control in trained individuals during a 6-week resistance training program, considering factors like sleep, diet, and fatigue that influence true load and daily readiness. This expands understanding beyond traditional one-repetition maximum tests.
The ketogenic diet (KD) involves significantly reducing daily carbohydrate intake to less than 50 grams, while increasing fat and possibly protein intake. Studies have explored its effects on athletic performance, particularly in endurance sports, showing no negative impact and even potential improvements in endurance. In strength training, combining KD with resistance training (RT) and high-protein intake has not been found to decrease muscle strength or power levels in some studies, although contradictory findings exist. Recent research suggests KD may aid overall weight loss but could have a small negative effect on fat-free mass and may not improve strength or high-intensity performance. Assessments of KD’s impact on muscle power or RT performance have used various methods, with mixed results. Most studies have focused on men, with limited research on women. Monitoring within-exercise variables like repetitions to failure, load displacement, and perceived effort may provide a more precise assessment of RT-induced adaptations during KD. This study aims to evaluate the impact of a 6-week KD on RT performance in resistance-trained individuals, focusing on volume load, number of repetitions, perceived exertion, movement velocity loss, and exertion index. It hypothesizes that RT performance may decline during the initial weeks of the KD intervention.
This study aimed to evaluate how a 6-week ketogenic diet (KD) impacted load management in resistance-trained individuals, focusing on factors like volume load, repetitions, and perceived exertion. Results showed that perceived exertion decreased over time, while effort increased notably after the initial ketosis induction. Volume load and repetitions decreased in the first week but gradually rose thereafter. Comparing KD with a standard diet, no significant differences were found in performance metrics such as repetitions and total tonnage. Optimal neuromuscular adaptations and strength gains in the bench press were associated with a volume load of 25% and intensities of 55% to 70% of 1-RM.
During the initial weeks of a ketogenic diet (KD), reduced carbohydrate intake may temporarily hinder resistance training (RT) performance. However, overall performance progression and perceived exertion are not significantly affected, likely due to physiological adaptation to using alternative energy sources, such as ketones. As insulin levels decrease from carb restriction, the liver produces ketones, primarily beta-hydroxybutyrate, which serves as an energy source for neurons, albeit after an adaptation period. Symptoms like fatigue, decreased energy, and appetite changes may occur during the initial phase, known as “keto flu.” Studies suggest that KD may not significantly impact performance in various training programs, including high-intensity interval training (HIIT) and CrossTraining, with similar outcomes observed in both ketogenic and non-ketogenic protocols, possibly due to metabolic flexibility achieved after full adaptation to nutritional ketosis.
The high dropout rate in the early weeks of ketogenic diet (KD) interventions impacts physical performance due to increased perceived exertion, affecting adherence to the program. Further research is needed to understand adherence issues, especially among those unfamiliar with carbohydrate restriction. Once individuals adapt to the metabolic changes of KD, no performance differences compared to high-carb diets are expected, potentially benefiting body composition and endurance. More studies are required to explore KD’s effects on hormone regulation and testosterone levels. For skeletal muscle hypertrophy, a training regimen of two days per week with 10 sets per session is recommended to mitigate KD’s initial adherence challenges without compromising resistance training (RT) performance, as recent findings suggest that carbohydrate intake doesn’t impact RT performance for workouts involving up to 10 sets per muscle group in energy-balanced states.
This study highlights limitations including a small sample size and a short intervention duration of six weeks. The absence of performance decline in participants following a ketogenic diet for six weeks doesn’t necessarily suggest superior effects compared to a higher carbohydrate diet with similar calorie content. Therefore, further research with controlled protocols comparing ketogenic and non-ketogenic diets while equating total calorie intake is essential to draw more conclusive findings, emphasizing the absence of a control group and potential confounding factors like ad libitum fat selection as significant limitations.
Resistance-trained individuals may initially experience performance declines and increased perceived effort when following a 6-week ketogenic diet, but it does not seem to affect their performance, volume load, repetitions, or velocity loss in the short term.
Source:
Salvador Vargas-Molina, Manuel García-Sillero, Diego A. Bonilla, Jorge L. Petro, Jerónimo García-Romero & Javier Benítez-Porres (2024) The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants, Journal of the International Society of Sports Nutrition, 21:1, DOI: 10.1080/15502783.2024.2306308