Document Detail

Capacity for moderate exercise in obese subjects after adaptation to a hypocaloric, ketogenic diet.
MedLine Citation:
PMID:  7000826     Owner:  NLM     Status:  MEDLINE    
To study the capacity for moderate endurance exercise and change in metabolic fuel utilization during adaptation to a ketogenic diet, six moderately obese, untrained subjects were fed a eucaloric, balanced diet (base line) for 2 wk, followed by 6 wk of a protein-supplemented fast (PSF), which provided 1.2 g of protein/kg ideal body wt, supplemented with minerals and vitamins. The mean weight loss was 10.6 kg. The duration of treadmill exercise to subjective exhaustion was 80% of base line after 1 wk of the PSF, but increased to 155% after 6 wk. Despite adjusting up to base line, with a backpack, the subjects' exercise weight after 6 wk of dieting, the final exercise test was performed at a mean of 60% of maximum aerobic capacity, whereas the base-line level was 76%. Resting vastus lateralis glycogen content fell to 57% of base line after 1 wk of the PSF, but rose to 69% after 6 wk, at which time no decrement in muscle glycogen was measured after >4 h of uphill walking. The respiratory quotient (RQ) during steady-state exercise was 0.76 during base line, and fell progressively to 0.66 after 6 wk of the PSF. Blood glucose was well maintained during exercise in ketosis. The sum of acetoacetate and beta hydroxybutyrate rose from 3.28 to 5.03 mM during exercise after 6 wk of the PSF, explaining in part the low exercise RQ. The low RQ and the fact that blood glucose and muscle glycogen were maintained during exhausting exercise after 6 wk of a PSF suggest that prolonged ketosis results in an adaptation, after which lipid becomes the major metabolic fuel, and net carbohydrate utilization is markedly reduced during moderate but ultimately exhausting exercise.
S D Phinney; E S Horton; E A Sims; J S Hanson; E Danforth; B M LaGrange
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical investigation     Volume:  66     ISSN:  0021-9738     ISO Abbreviation:  J. Clin. Invest.     Publication Date:  1980 Nov 
Date Detail:
Created Date:  1981-01-29     Completed Date:  1981-01-29     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7802877     Medline TA:  J Clin Invest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1152-61     Citation Subset:  AIM; IM; S    
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MeSH Terms
Exercise Test
Fatty Acids, Nonesterified / blood
Glucagon / blood
Glycogen / analysis
Insulin / blood
Muscles / analysis
Obesity / blood,  diet therapy*,  physiopathology
Oxygen Consumption
Physical Exertion*
Pyruvates / blood
Thyroid Hormones / blood
Grant Support
Reg. No./Substance:
0/Fatty Acids, Nonesterified; 0/Pyruvates; 0/Thyroid Hormones; 11061-68-0/Insulin; 9005-79-2/Glycogen; 9007-92-5/Glucagon

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