The effect of a short-term ketogenic diet on exercise efficiency during graded exercise in healthy adults

Wonhee Cho, Hwaebong Jung, Sunghyun Hong, Hyuk In Yang, Dong-Hyuk Park, Sang-Hoon Suh, Dong Hoon Lee, Yong-Sahm Choe, Joon Young Kim, Wooyoung Lee, Justin Y Jeon

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: We examined the effects of short-term KD on exercise efficiency and hormonal response during and after the graded exercise testing.

METHODS: Fourteen untrained healthy adults (8 males, 6 females, age 26.4 ± 3.1 [SD] years; BMI 24.8 ± 4.6 kg/m2; peak VO2max 54.0 ± 5.8 ml/kg FFM/min) completed 3-days of a mixed diet (MD) followed by another 3-days of KD after 3-days of washout period. Upon completion of each diet arm, participants underwent graded exercise testing with low- (LIE; 40% of VO2max), moderate- (MIE; 55%), and high-intensity exercise (HIE; 70%). Exercise efficiency was calculated as work done (kcal/min)/energy expenditure (kcal/min).

RESULTS: Fat oxidation during the recovery period was higher in KD vs. MD. Despite identical workload during HIE, participants after having KD vs. MD showed higher energy expenditure and lower exercise efficiency (10.1 ± 0.7 vs. 12.5 ± 0.3%, p < .01). After KD, free fatty acid (FFA) concentrations were higher during MIE and recovery vs. resting, and beta-hydroxybutylate (BOHB) was lower at HIE vs. resting. Cortisol concentrations after KD was higher during recovery vs. resting, with no significant changes during graded exercise testing after MD.

CONCLUSIONS: Our data suggest that short-term KD is favorable to fat metabolism leading increased circulating FFA and BOHB during LIE to MIE. However, it is notable that KD may cause 1) exercise inefficiency manifested by increased energy expenditure and 2) elevated exercise stress during HIE and recovery. Trial registration: KCT0005172, International Clinical Trials Registry Platform.

Original languageEnglish (US)
Pages (from-to)2264278
JournalJournal of the International Society of Sports Nutrition
Issue number1
StatePublished - Dec 2023


  • Adult
  • Female
  • Humans
  • Male
  • Young Adult
  • Diet, Ketogenic
  • Energy Metabolism
  • Exercise/physiology
  • Exercise Test
  • Oxidation-Reduction


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