The individuals who followed the ketogenic diet saw a sizeable spike in fat usage and a decrease in carbohydrate usage during the one-mile workout. On average, fat utilization increased by 190%, while carbohydrate utilization decreased by 20%. The low-carb and high-carb groups showed no variation between the 1-mile and 6 X 800-meter sprint tests. This study challenges the notion that high carbohydrates diets are superior to low-carb diets for improving performance.
KETO WORKOUT PLAN AND DIET FOR EXERCISE SUMMARY
- The individuals who followed the keto workout plan saw a sizeable spike in fat usage and a decrease in carbohydrate usage during the one-mile workout. On average, fat utilization increased by 190%, while carbohydrate utilization decreased by 20%.
- The low-carb and high-carb groups showed no variation between the 1-mile and 6 X 800-meter sprint tests.
- This study challenges the notion that high carbohydrates diets are superior to low-carb diets for improving performance.
LIFTING WEIGHT ON KETO IS NOT DETRIMENTAL
In recent years, high-fat intake, low-carb and ketogenic diets have been advocated as beneficial for losing weight but detrimental to performance (i.e., especially during highly intensive workouts). Many coaches and sports scientists have suggested that weight lifting on keto decreases performance and muscle growth. Many athletes are told to consume a high-carbohydrate diet to enhance recovery after exercise, improve performance, and gain muscle.
Recent studies have questioned the claim that weightlifting on keto workout plans and diets will decrease performance, with bouts lasting less than an hour. Carbohydrate intake per se is unlikely to affect strength training performance in a fed state in exercise routines consisting of up to 10 sets per muscle group. (Henselmans et al., 2022)
THE PROS AND CONS OF KETO DIETS
Ketogenic and alternate versions, such as the keto intermittent fasting diets, have resulted in greater fat loss and short-term weight loss. Still, many people start eating more carbohydrates and gaining long-term weight due to the difficulty of staying on a ketogenic diet. (Hansen et al., 2023) Ketogenic diets result in an increase in fat utilization during exercise. Since the human body has abundant fat cells compared to glycogen stores, this can be advantageous for exercise. (Havemann et al., 2006)
HOW TO ENTER KETOSIS?
When following a low-carb ketogenic diet, your body switches from utilizing carbohydrates as an energy source to fats as an energy source. A ketogenic diet is usually defined as consuming less than 50 grams of carbohydrates per day, and “low-carbohydrate” is usually 50-150 grams daily. (Gomez-Arbelaez et al., 2017; Johnstone et al., 2008)
The process is called “ketosis.” During ketosis, blood ketone levels rise dramatically. Ketones are the breakdown products of fat used to fuel cells that normally depend on glucose. Many people want to know how to get into ketosis fast!
Achieving ketosis by restricting carbohydrates and intense exercise will quickly result in an elevation in blood ketones. (Harvey et al., 2019)
DOES A KETO WORKOUT PLAN DECREASE PERFORMANCE?
Previous research has shown that ketogenic diets result in a decrease in performance. (Burke et al., 2017; Burke et al., 2021) These authors suggested that carbohydrates are needed for short, high-intensity exercise. Part of the reason why ketogenic diets may reduce performance may be due to nutrient deficiencies, as ketogenic diets cause increased electrolyte excretion. (Bostock et al., 2020)
NEW STUDY ON KETO WORKOUT PLANS
A new research study published in Frontier in Medicine questions any decreases in performance following a keto workout plan. The study had 10 trained male athletes, 40 years of age, complete two 31-day dietary interventions separated by a 2-week washout period:
4 Weeks of Low Carb, High Fat (LCHF): < 50 grams of carbohydrates, 15%–20% protein, and 75%–80% fat.
4 Weeks of High Carb, low-fat diet (HCLF): 20% fat, 60%–65% carbohydrate, 15%–20% protein.
Unlike other studies, the researchers had the ketogenic diet phase supplemented with 1-2 grams of sodium per day from bouillon cubes or homemade broth. As mentioned previously, the reason for this is that the ketogenic diet enhances electrolyte excretion. The subjects had blood ketones measured frequently to confirm they were in ketosis. The amount of protein was the same between the diets; the only differences were in fat.
The researchers measured performance (i.e., 1 mile trial time, 6 X 800 meter sprint performance) in conjunction with body composition, glucose, ketones, cardiovascular, and metabolic profiles (i.e., cholesterol, LDL, HDL, etc.).
SHOCKING INCREASES IN FAT METABOLISM ON LOW-CARB DIETS
The finding was a big shocker for the research community. When the subjects were on the ketogenic diet, during the 1-mile exercise, the average fat oxidation increased (+190%), and average carbohydrate oxidation decreased (-20%). During the repeated sprint test, average fat oxidation increased (+92%), and average carbohydrate oxidation decreased (-54%). There was no difference in performance between the LCHF and HCLW diets.
Like other studies, the LCHF had lower blood glucose levels than the higher carbohydrate diet. The concerning finding was that the athletes on the HCLF had blood glucose levels that were in the pre-diabetic range while following the HCLF diet. (Prins et al., 2023)
This study challenges the notion that fat is an inferior metabolic fuel unable to support high-intensity exercise. This study also challenges the belief that you need to “carbohydrate load” to enhance recuperation and performance. The low-carb, high-healthy fat group with adequate protein intake performed similarly to the high-carb group in exercises traditionally thought of as carbohydrate-dominant exercises. This study had only 10 subjects, but I am sure more studies will be re-testing the results.
REFERENCES
Bostock, E. C. S., Kirkby, K. C., Taylor, B. V., & Hawrelak, J. A. (2020). Consumer Reports of “Keto Flu” Associated With the Ketogenic Diet. Frontiers in Nutrition, 7, 20-20. https://doi.org/10.3389/fnut.2020.00020
Burke, L. M., Ross, M. L., Garvican-Lewis, L. A., Welvaert, M., Heikura, I. A., Forbes, S. G., Mirtschin, J. G., Cato, L. E., Strobel, N., Sharma, A. P., & Hawley, J. A. (2017). Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol, 595(9), 2785-2807. https://doi.org/10.1113/jp273230
Burke, L. M., Whitfield, J., Heikura, I. A., Ross, M. L. R., Tee, N., Forbes, S. F., Hall, R., McKay, A. K. A., Wallett, A. M., & Sharma, A. P. (2021). Adaptation to a low carbohydrate high fat diet is rapid but impairs endurance exercise metabolism and performance despite enhanced glycogen availability. J Physiol, 599(3), 771-790. https://doi.org/10.1113/jp280221
Gomez-Arbelaez, D., Bellido, D., Castro, A. I., Ordoñez-Mayan, L., Carreira, J., Galban, C., Martinez-Olmos, M. A., Crujeiras, A. B., Sajoux, I., & Casanueva, F. F. (2017). Body Composition Changes After Very-Low-Calorie Ketogenic Diet in Obesity Evaluated by 3 Standardized Methods. J Clin Endocrinol Metab, 102(2), 488-498. https://doi.org/10.1210/jc.2016-2385
REFERENCES
Hansen, C. D., Gram-Kampmann, E. M., Hansen, J. K., Hugger, M. B., Madsen, B. S., Jensen, J. M., Olesen, S., Torp, N., Rasmussen, D. N., Kjærgaard, M., Johansen, S., Lindvig, K. P., Andersen, P., Thorhauge, K. H., Brønd, J. C., Hermann, P., Beck-Nielsen, H., Detlefsen, S., Hansen, T., . . . Krag, A. (2023). Effect of Calorie-Unrestricted Low-Carbohydrate, High-Fat Diet Versus High-Carbohydrate, Low-Fat Diet on Type 2 Diabetes and Nonalcoholic Fatty Liver Disease : A Randomized Controlled Trial. Ann Intern Med, 176(1), 10-21. https://doi.org/10.7326/m22-1787
Harvey, K. L., Holcomb, L. E., & Kolwicz, S. C., Jr. (2019). Ketogenic Diets and Exercise Performance. Nutrients, 11(10), 2296. https://doi.org/10.3390/nu11102296
Havemann, L., West, S. J., Goedecke, J. H., Macdonald, I. A., St Clair Gibson, A., Noakes, T. D., & Lambert, E. V. (2006). Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. J Appl Physiol (1985), 100(1), 194-202. https://doi.org/10.1152/japplphysiol.00813.2005
Henselmans, M., Bjørnsen, T., Hedderman, R., & Vårvik, F. T. (2022). The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review. Nutrients, 14(4). https://doi.org/10.3390/nu14040856
REFERENCES
Johnstone, A. M., Horgan, G. W., Murison, S. D., Bremner, D. M., & Lobley, G. E. (2008). Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr, 87(1), 44-55. https://doi.org/10.1093/ajcn/87.1.44
Prins, P. J., Noakes, T. D., Buga, A., D’Agostino, D. P., Volek, J. S., Buxton, J. D., Heckman, K., Jones, D. W., Tobias, N. E., Grose, H. M., Jenkins, A. K., Jancay, K. T., & Koutnik, A. P. (2023). Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males [Original Research]. Frontiers in Nutrition, 10. https://doi.org/10.3389/fnut.2023.1084021
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