A Carbohydrate Ingestion Intervention in an Elite Athlete Who Follows a Low-Carbohydrate High-Fat Diet

in International Journal of Sports Physiology and Performance
Restricted access

Purchase article

USD  $24.95

Student 1 year subscription

USD  $107.00

1 year subscription

USD  $142.00

Student 2 year subscription

USD  $203.00

2 year subscription

USD  $265.00

This case study documents the performance of an elite-level, exceptionally well-fat-adapted endurance athlete as he reintroduced carbohydrate (CHO) ingestion during high-intensity training. He had followed a strict low-CHO high-fat (LCHF) diet for 2 y, during which he ate approximately 80 g of CHO per day and trained and raced while ingesting only water. While following this diet, he earned numerous podium finishes in triathlons of various distances. However, he approached the authors to test whether CHO supplementation during exercise would further increase his high-intensity performance without affecting his fat adaptation. This 7-wk n = 1 investigation included a 4-wk habitual LCHF diet phase during which he drank only water during training and performance trials and a 3-wk habitual diet plus CHO ingestion phase (LCHF + CHO) during which he followed his usual LCHF diet but ingested 60 g/h CHO during 8 high-intensity training sessions and performance trials. After each phase, rates of fat oxidation and 30-s sprint, 4-min sprint, 20-km time trial (TT), and 100-km TT performances were measured. Compared with LCHF, 20-km TT time improved by 2.8% after LCHF + CHO, which would be a large difference in competition. There was no change in 30-s sprint power, a small improvement in 4-min sprint power (1.6%), and a small reduction in 100-km TT time (1.1%). The authors conclude that CHO ingestion during exercise was likely beneficial for this fat-adapted athlete during high-intensity endurance-type exercise (4–30 min) but likely did not benefit his short-sprint or prolonged endurance performance.

The authors are with the Div of Exercise Science and Sports Medicine, Dept of Human Biology, University of Cape Town, Cape Town, South Africa.

Webster (wbschr002@myuct.ac.za) is corresponding author.
  • 1.

    Volek JS, Freidenreich DJ, Saenz C, et al. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism. 2016;65(3):100110. PubMed ID: 26892521 doi:10.1016/j.metabol.2015.10.028

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2.

    Burke LM. Re-examining high-fat diets for sports performance: did we call the ‘Nail in the Coffin’ too soon? Sports Med. 2015;45(suppl 1):3349. doi:10.1007/s40279-015-0393-9

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Burke LM, Ross ML, Garvican-Lewis LA, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol. 2017;595(9):27852807. PubMed ID: 28012184 doi:10.1113/JP273230

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4.

    Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44(suppl 1):S25S33. doi:10.1007/s40279-014-0148-z

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Webster CC, Noakes TD, Chacko SK, Swart J, Kohn TA, Smith JA. Gluconeogenesis during endurance exercise in cyclists habituated to a long-term low carbohydrate high-fat diet. J Physiol. 2016;594(15):43894405. PubMed ID: 26918583 doi:10.1113/JP271934

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6.

    Lamberts RP, Swart J, Woolrich RW, Noakes TD, Lambert MI. Measurement error associated with performance testing in well-trained cyclists: application to the precision of monitoring changes in training status. Int SportMed J. 2009;10(1):3344.

    • Search Google Scholar
    • Export Citation
  • 7.

    Stellingwerff T, Spriet LL, Watt MJ, et al. Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. Am J Physiol Endocrinol Metab. 2006;290(2):E380E388. doi:10.1152/ajpendo.00268.2005

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8.

    de Ataide e Silva T, Di Cavalcanti Alves de Souza ME, de Amorim JF, Stathis CG, Leandro CG, Lima-Silva AE. Can carbohydrate mouth rinse improve performance during exercise? A systematic review. Nutrients. 2014;6(1):110. doi:10.3390/nu6010001

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9.

    Kasper AM, Cocking S, Cockayne M, et al. Carbohydrate mouth rinse and caffeine improves high-intensity interval running capacity when carbohydrate restricted. Eur J Sport Sci. 2016;16(5):560568. PubMed ID: 26035740 doi:10.1080/17461391.2015.1041063

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10.

    Luden ND, Saunders MJ, D’Lugos AC, et al. Carbohydrate mouth rinsing enhances high intensity time trial performance following prolonged cycling. Nutrients. 2016;8(9):576. PubMed ID: 27657117 doi:10.3390/nu8090576

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Coyle EF, Jeukendrup AE, Wagenmakers AJ, Saris WH. Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise. Am J Physiol. 1997;273(2 pt 1):E268E275. PubMed ID: 9277379

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Cox GR, Clark SA, Cox AJ, et al. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. J Appl Physiol. 2010;109(1):126134. doi:10.1152/japplphysiol.00950.2009

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 936 936 85
Full Text Views 33 33 1
PDF Downloads 10 10 0