Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis.
This study aimed to verify the effect of aerobic exercise performed in the fasted v. fed states on fat and carbohydrate metabolism in adults. Searches were conducted in March 2015, and updated in July 2016, using PubMed®, Scopus and Cochrane databases (terms: 'fasting', 'exercise', 'aerobic exercise', 'substrate', 'energy metabolism', 'fat', 'glucose', 'insulin' and 'adult') and references from selected studies. Trials that compared the metabolic effects of aerobic exercise (duration ≤120 min) performed in the fasted v. fed states in adults were accepted. The outcomes evaluated were fat oxidation during exercise and the plasma concentrations of insulin, glucose and NEFA before and immediately after exercise; two independent reviewers extracted the data (A. F. V. and L. C.). The results were presented as weighted mean differences between treatments, with 95 % CI. Of 10 405 articles identified, twenty-seven studies - with a total of 273 participants - were included. There was a significant increase in fat oxidation during exercise performed in the fasted, compared with fed, state (-3·08 g; 95 % CI -5·38, -0·79; I 2 39·1 %). The weighted mean difference of NEFA concentrations was not significantly different between states (0·00 mmol/l; 95 % CI -0·07, 0·08; I 2 72·7 %). However, the weighted mean differences of glucose (0·78 mmol/l; 95 % CI 0·43, 1·14; I 2 90·8 %) and insulin concentrations (104·5 pmol/l; 95 % CI 70·8, 138·2; I 2 94·5 %) were significantly higher for exercise performed in the fed state. We conclude that aerobic exercise performed in the fasted state induces higher fat oxidation than exercise performed in the fed state.
2Research Group on Water and Land Activities,Federal University of Rio Grande do Sul, 750, Felizardo Street, 90690-200Porto Alegre,Brazil.
Alexandra Ferreira
AF
Vieira
1Physical Education, Physiotherapy and Dance School,Federal University of Rio Grande do Sul, 750, Felizardo Street, 90690-200Porto Alegre,Brazil.
Rochelle Rocha
RR
Costa
1Physical Education, Physiotherapy and Dance School,Federal University of Rio Grande do Sul, 750, Felizardo Street, 90690-200Porto Alegre,Brazil.
Rodrigo Cauduro Oliveira
RC
Macedo
1Physical Education, Physiotherapy and Dance School,Federal University of Rio Grande do Sul, 750, Felizardo Street, 90690-200Porto Alegre,Brazil.
Leandro
L
Coconcelli
1Physical Education, Physiotherapy and Dance School,Federal University of Rio Grande do Sul, 750, Felizardo Street, 90690-200Porto Alegre,Brazil.
Luiz Fernando Martins
LF
Kruel
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005215:Fasting / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005502:Food; D006801:Humans; D007328:Insulin / Q000097:blood; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D010084:Oxidation-Reduction
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin
 IMTG;  intramuscular TAG; Energy metabolism; Exercise; Fasting; Reviews