Effects of Ad libitum Low-Carbohydrate High-Fat Dieting in Middle-Age Male Runners

Heatherly, Alexander J.; Killen, Lauren G; Smith, Ashton F; Waldman, Hunter S.; Seltmann, Christie L; Hollingsworth, Angela; OʼNeal, Eric K

doi:10.1249/mss.0000000000001477

Cited by 36 publications

(77 citation statements)

References 24 publications

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“…Five of seven studies examined VO 2 max outcomes in only male athletes Bailey and Hennessy Journal of the International Society of Sports Nutrition (2020) 17:33 [12][13][14][15][16]. However, among those studies, athlete type varied: one study recruited male runners [13], one recruited male race walkers [12], one recruited male cyclists [15], and two recruited a mixed sample of male endurance athletes [14,16]. Two of the seven studies recruited both male and female athletes; one recruited a sample of race walkers [7] and the other recruited a sample of mixed endurance athletes [17].…”

Section: Descriptive Resultsmentioning

confidence: 99%

“…All seven studies included an EAKD (< 50 g daily carbohydrate). Of the six trial studies, all included a standard, high carbohydrate comparison diet [7,[12][13][14][15][16], while the case study provided no comparison diet [17]. Studies either provided participants with meals [7,12,15] or with dietary guidance, including sample meal plans [13,14,16,17].…”

Section: Descriptive Resultsmentioning

confidence: 99%

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A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect?

Bailey

Hennessy

2020

Journal of the International Society of Sports Nutrition

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Background: The ketogenic diet has become popular among endurance athletes as a performance enhancer. This paper systematically reviews the evidence regarding the effect of the endurance athlete's ketogenic diet (EAKD) on maximal oxygen consumption (VO 2 max) and secondary performance outcomes. Methods: PubMed and Web of Science searches were conducted through November 2019. Inclusion criteria were documentation of EAKD (< 50 g daily carbohydrate consumed by endurance athletes), ketosis achieved (measured via serum biomarker), VO 2 max and/or secondary outcomes, English language, and peer reviewed-publication status. Articles were excluded if they were not a primary source or hypotheses were not tested with endurance athletes (i.e., individuals that compete at submaximal intensity for extended time periods). Study design, diet composition, adherence assessment, serum biomarkers, training protocols, and VO 2 max/secondary outcomes were extracted and summarized. Results: Searches identified seven articles reporting on VO 2 max and/or secondary outcomes; these comprised six intervention trials and one case study. VO 2 max outcomes (n = 5 trials, n = 1 case study) were mixed. Two of five trials reported significant increases in VO 2 max across all diets; while three trials and one case study reported no significant VO 2 max findings. Secondary outcomes (n = 5 trials, n = 1 case study) were Time to Exhaustion (TTE; n = 3 articles), Race Time (n = 3 articles), Rating of Perceived Exertion (RPE; n = 3 articles), and Peak Power (n = 2 articles). Of these, significant findings for EAKD athletes included decreased TTE (n = 1 article), higher RPE (n = 1 article), and increased Peak Power (n = 1 article). Conclusion: Limited and heterogeneous findings prohibit definitive conclusions regarding efficacy of the EAKD for performance benefit. When compared to a high carbohydrate diet, there are mixed findings for the effect of EAKD consumption on VO 2 max and other performance outcomes. More randomized trials are needed to better understand the potentially nuanced effects of EAKD consumption on endurance performance. Researchers may also consider exploring the impact of genetics, recovery, sport type, and sex in moderating the influence of EAKD consumption on performance outcomes.

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Section: Descriptive Resultsmentioning

confidence: 99%

Section: Descriptive Resultsmentioning

confidence: 99%

A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect?

Bailey

Hennessy

2020

Journal of the International Society of Sports Nutrition

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“…A 3-week study in elite race-walkers following LCHF found that increased rates of fat oxidation were accompanied (and offset) by an increased oxygen cost of walking, resulting in a lack of improvement in a 10 km race while performance improvements were observed in high-CHO and periodized-CHO groups [29]. Similar findings of decreased economy have also been observed in recreational runners on LCHF [53], while three days of high-CHO diet improved cycling gross efficiency compared with low and moderate-CHO diets [56].…”

Section: Low-carb High-fatmentioning

confidence: 71%

“…Well-trained athletes are able to oxidize more fat for fuel during exercise compared with recreationally trained or untrained individuals [50,51], and correlations have been observed between maximal rate of fat oxidation and endurance performance [52]. At the same time, it is clear that LCHF dietary interventions are able to drastically increase rates of fat oxidation regardless of training status [28,29,53]. Arguments in favor of trying to increase fat-burning capacity focus around the ability to utilize the large stores of endogenous lipids found even in very lean athletes, while preserving the relatively limited supply of muscle and liver glycogen.…”

Section: Low-carb High-fatmentioning

confidence: 99%

Dietary Manipulations Concurrent to Endurance Training

Rothschild¹,

Earnest

2018

JFMK

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The role of an athlete’s dietary intake (both timing and food type) goes beyond simply providing fuel to support the body’s vital processes. Nutritional choices also have an impact on the metabolic adaptations to training. Over the past 20 years, research has suggested that strategically reducing carbohydrate (CHO) availability during an athlete’s training can modify the metabolic responses in lieu of simply maintaining a high CHO diet. Several methods have been explored to manipulate CHO availability and include: Low-carb, high-fat (LCHF) diets, performing two-a-day training without glycogen restoration between sessions, and a “sleep-low” approach entailing a glycogen-depleting session in the evening without consuming CHO until after a morning training session performed in an overnight fasted state. Each of these methods can confer beneficial metabolic adaptations for the endurance athlete including increases in mitochondrial enzyme activity, mitochondrial content, and rates of fat oxidation, yet data showing a direct performance benefit is still unclear.

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“…Movement economy was impaired by LCHF diets between 64-90% VO 2max in elite male race walkers (7,8,14,15) and recreationally-trained male runners (30), and improved by a HCLF diet at 70-75% VO 2max in trained male cyclists (12). However, decreased cycling e ciency following LCHF has also been reported at ~40-45% VO 2max in untrained males (24).…”

Section: Discussionmentioning

confidence: 98%

Effect of low- and high-carbohydrate diets on swimming economy: a crossover study

Bestard

Rothschild

Crocker

2020

Preprint

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Background: Swimming economy refers to the rate of energy expenditure relative to swimming speed of movement, is inversely related to the energetic cost of swimming, and is as a key factor influencing endurance swimming performance. The objective of this study was to determine if high-carbohydrate, low-fat (HCLF) and low-carbohydrate, high-fat (LCHF) diets affect energetic cost of submaximal swimming. Methods: Eight recreational swimmers consumed two 3-day isoenergetic diets in a crossover design. Diets were tailored to individual food preferences, and macronutrient consumption was 69-16-16% and 16-67-18% carbohydrate-fat-protein for the HCLF and LCHF diets, respectively. Following each 3-day dietary intervention, participants swam in a flume at velocities associated with 50, 60, and 70% of their maximal aerobic capacity (VO2max). Expired breath was collected and analyzed while they swam which enabled calculation of the energetic cost of swimming. A paired t-test compared macronutrient distribution between HCLF and LCHF diets, while repeated-measures ANOVA determined effects of diet and exercise intensity on physiological endpoints.Results: Respiratory exchange ratio was significantly higher in HCLF compared to LCHF (p = 0.003), but there were no significant differences in the rate of oxygen consumption (p = 0.499) or energetic cost of swimming (p = 0.324) between diets. Heart rate did not differ between diets (p = 0.712), but oxygen pulse, a non-invasive surrogate for stroke volume, was greater following the HCLF diet (p = 0.029). Conclusions: A 3-day high-carbohydrate diet increased carbohydrate utilization but did not affect swimming economy at 50-70% VO2max. As these intensities are applicable to ultramarathon swims, future studies should use higher intensities that would be more relevant to shorter duration events.

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Effects of Ad libitum Low-Carbohydrate High-Fat Dieting in Middle-Age Male Runners

Cited by 36 publications

References 24 publications

A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect?

A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect?

Dietary Manipulations Concurrent to Endurance Training

Effect of low- and high-carbohydrate diets on swimming economy: a crossover study

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