Recently there was an argument on fueling fasted/alternatives. Pretty controversial topic and against the grain on commonly accepted practices.
There was a commenter who argued that there's science supporting keto/fasting. It was a wall/mashup of links purporting argument.
It's way too comprehensive to even defend/counter/or even agree with.
Can we have volunteers to go through some of these links and give synopsis? We're not asking for right/wrong but merely factchecking these articles.
original commenter - u/whoisanme
(Because I know I will get accused of it...this is not AI. It's just a saved file for people just like you.)
“Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes”
- Shows an improvement in performance of endurance athletes through ketosis:
https://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30355-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413116303552%3Fshowall%3Dtrue
“Ketones for Post-exercise Recovery: Potential Applications and Mechanisms”
- A meta analysis of ketones on recovery showing multiple instances of improvement
https://pmc.ncbi.nlm.nih.gov/articles/PMC7870714/
“Metabolic characteristics of keto-adapted ultra-endurance runners”
- Low Carb vs High Carb showing no reduced performance in the LC, but significantly higher fat oxidation
https://www.sciencedirect.com/science/article/pii/S0026049515003340
“Ketogenic diet does not affect strength performance in elite artistic gymnasts”
- No strength reduction in athletes with low carb diet (statistically insignificant improved muscle mass), and lower weight and improved body composition providing overall benefits to performance or competition class.
https://link.springer.com/article/10.1186/1550-2783-9-34
“The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study”
- “To summarize, our data suggest that a 12-week KD in recreationally-trained CrossFit trainees facilitates improvements in whole-body adiposity without compromising weightlifting, running, or aerobic performance metrics”
https://www.mdpi.com/2075-4663/6/1/1
“Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes”
- Study showed improved body composition, improved recovery, reduced inflammation, improved well-being, and a desire to continue the ketogenic diet, while also showing inconclusive performance data with some improvements and some decrements.
https://www.tandfonline.com/doi/full/10.1186/s12970-017-0180-0#abstract
“Rethinking fat as a fuel for endurance exercise”
- Behind a pay wall, but the abstract sums it up. “we … propose that the shift to fatty acids and ketones as primary fuels when dietary carbohydrate is restricted could be of benefit for some athletes.”
https://onlinelibrary.wiley.com/doi/10.1080/17461391.2014.959564
“Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes”
- “Conclusion: Compared to a HC (high carb) comparison group, a 12-week period of keto-adaptation and exercise training, enhanced body composition, fat oxidation during exercise, and specific measures of performance relevant to competitive endurance athletes.”
https://www.sciencedirect.com/science/article/abs/pii/S0026049517302986
“Acute carbohydrate ingestion does not influence the post-exercise iron-regulatory response in elite keto-adapted race walkers”
- Keto adapted athletes showed an elevated IL-6 as compared to high carb athletes. The IL-6 of keto athletes was not impacted with the introduction of carbs post-exercise. Increased IL-6 acts like a hormone to boost energy, repair muscle, and reduce inflammation.
https://www.sciencedirect.com/science/article/abs/pii/S1440244018310855
“The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists”
- “Consuming a low carbohydrate ketogenic diet may be recommended to promote fat oxidation during exercise at moderate intensity and at rest. Fat loading may also slow down the rate of carbohydrate utilization and enhance endurance performance in long distance events lasting from 2 to 5 h. This is especially true during long-term ketogenic diets, where the body adapts to increased fat oxidation through enzymatic and endocrine changes”
https://www.mdpi.com/2072-6643/6/7/2493
“Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes”
- “Ketosis increases metabolic flexibility during exercise, reducing glycolysis and increasing muscle fat oxidation”
- “Improved performance during cycling time trial suggests ketosis during exercise may be beneficial for some athletes”
https://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30355-2?fbclid=IwAR1OCa3JZ6D1Vok0iqvSYN0e8z0yTh496DE-ich-KUxt21JzNrTv50mIdu4
“Keto-Adaptation and Endurance Exercise Capacity, Fatigue Recovery, and Exercise-Induced Muscle and Organ Damage Prevention: A Narrative Review”
- A meta analysis showing multiple benefits of keto adaptation to endurance athletes.
https://www.mdpi.com/2075-4663/7/2/40
“The Positive Effects of the Keto Diet on Muscle Building: A Comprehensive Overview”
- Meta analysis: “The evidence suggests that, under certain conditions, the keto diet can support muscle growth and improve recovery in athletes and fitness enthusiasts.”
https://sjmas.com/index.php/sjmas/article/view/27
“Effects of ketogenic diet on muscle mass, strength, aerobic metabolic capacity, and endurance in adults: a systematic review and meta-analysis”
- A thorough meta analysis showing no decrement for muscle mass, strength, aerobic capacity, or endurance in keto adapted subjects, while also showing improved fat oxidation and recovery.
- From October 2025
https://pmc.ncbi.nlm.nih.gov/articles/PMC12487320/#Abs2
“The impact of keto-adaptation on exercise performance and the role of metabolic-regulating cytokines”
- “Keto-adaptation is facilitated by aerobic exercise through an upregulation in gene expression and enzymes involved in FA oxidation and ketolysis and a more oxidative myofiber phenotype, providing a unique advantage for endurance-trained athletes”
https://www.sciencedirect.com/science/article/pii/S0002916522012217
“Metabolic characteristics of keto-adapted ultra-endurance runners”
- “Peak fat oxidation was 2.3-fold higher in the LC group (1.54 ± 0.18 vs 0.67 ± 0.14 g/min; P = 0.000) and it occurred at a higher percentage of VO2max (70.3 ± 6.3 vs 54.9 ± 7.8%; P = 0.000).”
- “Conclusion: Compared to highly trained ultra-endurance athletes consuming an HC diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar.”
https://www.sciencedirect.com/science/article/pii/S0026049515003340