Fat and Carbohydrate Metabolism in Fasted vs Fed Aerobic Exercise: A Systematic Review and Meta-Analysis
Vieira AF, Costa RR, Macedo RCO, Coconcelli L, Kruel LFM
Evidence is still building up
Summary
A meta-analysis showing that fasted aerobic exercise acutely increases fat oxidation during exercise compared with fed exercise. However, this acute difference in substrate use does not translate into long-term differences in body fat or composition, which depend on total energy balance.
Key findings
- 1
Fasted aerobic exercise acutely increases fat oxidation during exercise compared with fed exercise
- 2
However this acute difference in substrate use does not translate into long-term differences in body fat or composition
- 3
Changes in body composition ultimately depend on total energy balance
- 4
It shows an acute metabolic difference, not a long-term body-composition difference; sampleSize is 0 because it was not pooled across studies (moderate confidence)
Related research
Fasted vs Fed Aerobic Exercise and Body Composition: A 4-Week RCT Under Caloric Restriction
Journal of the International Society of Sports Nutrition, 2014
In 20 healthy young women (10 per group) performing 60 minutes of aerobic exercise 3 times/week for 4 weeks while all followed a caloric deficit, reductions in body weight and fat mass were similar between fasted and fed groups, suggesting the driver is total energy balance rather than fasted vs fed state.
Fasted vs Fed Exercise for Body Composition: A Systematic Review and Meta-Analysis
Journal of Functional Morphology and Kinesiology, 2017
A meta-analysis pooling 5 studies (n=96) comparing fasted vs fed exercise found trivial-to-small effect sizes for body weight and body composition, with no clear evidence that fasted exercise is superior.
Articles featuring this study
Last checked: