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Cited by 422Diet and metabolism studiesMuscle metabolism and nutritionCardiovascular and exercise physiology

The human metabolic response to chronic ketosis without caloric restriction: Preservation of submaximal exercise capability with reduced carbohydrate oxidation

Phinney, S.D., Bistrian, B.R., Evans, W.J., Gervino, E., Blackburn, G.L.·1983·Metabolism
DOI 10.1016/0026-0495(83)90106-3
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Abstract

To study the effect of chronic ketosis on exercise performance in endurance-trained humans, five well-trained cyclists were fed a eucaloric balanced diet (EBD) for one week providing 35-50 kcal/kg/d, 1.75 g protein/kg/d and the remainder of kilocalories as two-thirds carbohydrate (CHO) and one-third fat. This was followed by four weeks of a eucaloric ketogenic diet (EKD), isocaloric and isonitrogenous with the EBD but providing less than 20 g CHO daily. Both diets were appropriately supplemented to meet the recommended daily allowances for vitamins and minerals. Pedal ergometer testing of maximal oxygen uptake (VO2max) was unchanged between the control week (EBD-1) and week 3 of the ketogenic diet (EKD-3). The mean ergometer endurance time for continuous exercise to exhaustion (ENDUR) at 62%-64% of VO2max was 147 minutes at EBD-1 and 151 minutes at EKD-4. The ENDUR steady-state RQ dropped from 0.83 to 0.72 (P less than 0.01) from EBD-1 to EKD-4. In agreement with this were a three-fold drop in glucose oxidation (from 15.1 to 5.1 mg/kg/min, P less than 0.05) and a four-fold reduction in muscle glycogen use (0.61 to 0.13 mmol/kg/min, P less than 0.01). Neither clinical nor biochemical evidence of hypoglycemia was observed during ENDUR at EKD-4. These results indicate that aerobic endurance exercise by well-trained cyclists was not compromised by four weeks of ketosis. This was accomplished by a dramatic physiologic adaptation that conserved limited carbohydrate stores (both glucose and muscle glycogen) and made fat the predominant muscle substrate at this submaximal power level.

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Crossref · 10.1016/0026-0495(83)90106-3

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  • A ketogenic diet containing less than 20 g of carbohydrate per day for 4 weeks resulted in hyperketonemia and increases in fat oxidation.

    “In the 1980s, a study with five subjects showed that a ketogenic diet, containing less than 20 g of carbohydrate per day, for a prolonged period of time (4 weeks) resulted in hyperketonemia and increases in fat oxidation [53].”

    From Periodized Nutrition for Athletes (2017) · cites this paper as [53]

  • To date, not a single study has demonstrated performance benefits of a ketogenic diet, including the early study that is often referred to.

    “However, it is important to realize that, to date, not a single study has demonstrated performance benefits of a ketogenic diet, including the early study that is often referred to [53].”

    From Periodized Nutrition for Athletes (2017) · cites this paper as [53]

  • In that study, exercise capacity was only tested at a low intensity and showed a large degree of variation; on average, there was no difference in exercise capacity before and after the ketogenic diet.

    “In this study, exercise capacity was only tested at a low intensity and showed a large degree of variation both between subjects and within subjects. On average, there was no difference in exercise capacity before and after the ketogenic diet.”

    From Periodized Nutrition for Athletes (2017) · cites this paper as [53]

  • In the 1983 study, results were skewed by a large increase in endurance in one subject, and the authors noted that enhanced utilisation of fat and sparing of carbohydrate at moderate intensity was a limitation of the intensity of exercise that can be performed and a throttling of function near VO2max.

    “Moreover, the results were skewed by a large increase in endurance in one subject, and the authors also noted that the enhanced utilisation of fat and sparing of carbohydrate at moderate intensity was “a limitation of the intensity of exercise that can be performed” and a “throttling of function near VO2max” [75].”

    From New strategies in sport nutrition to increase exercise performance (2016) · cites this paper as [75]

  • At the time of the first study, the available literature on such a diet was limited to a single investigation of a 4-wk exposure in well-trained endurance athletes.

    “At the time of undertaking our first study, the available literature on such a diet was limited to a single investigation of a 4-wk exposure in well-trained endurance athletes [10].”

    From Crisis of confidence averted: impairment of exercise economy and performance in elite race walkers by ketogenic low carbohydrate, high fat (LCHF) diet is reproducible (2020) · cites this paper as [10]

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Authors
Phinney, S. D., Bistrian, B. R., Evans, W. J., Gervino, E., & Blackburn, G. L.
Affiliations
  • Massachusetts Institute of Technology (US)
  • Harvard University (US)
  • Boston University (US)
ORCID
Venue
Metabolism
Publisher
Elsevier BV
Published
1983-08
Volume
32
Issue
8
Pages
769-776
ISSN
0026-0495 (ISSN-L)
DOI
10.1016/0026-0495(83)90106-3
OpenAlex
W2113645942
Cited by
422
References
23
Citations by year
2026: 5 · 2025: 19 · 2024: 12 · 2023: 17 · 2022: 20 · 2021: 25 · 2020: 38 · 2019: 19 · 2018: 31 · 2017: 28 · 2016: 12 · 2015: 15 · 2014: 11 · 2013: 12 · 2012: 4
FWCI
2.06
Type
journal article
Language
en
Open access
closed
Licence
Locations
  • Metabolism (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Physiology › Diet and metabolism studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
Keywords
ketogenic diet, eucaloric diet, endurance exercise, submaximal exercise, carbohydrate oxidation, muscle glycogen, fat oxidation, VO2max, respiratory quotient, hypoglycemia, endurance cyclists
MeSH terms
Acidosis, Adult, Blood Glucose, Energy Intake, Diet, Physical Exertion, Glycogen, Humans, Ketosis, Male, Muscles, Oxygen Consumption, Physical Endurance, Carbohydrate Metabolism

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