Metabolic impact of feeding prior to a 60-min bout of moderate-intensity exercise in females in a fasted state

Ratliff, Kayla M.; Kerksick, Chad M.; Moon, Jessica M.; Hagele, Anthony M.; Boring, Johnathan L.; Walden, Kylie E.; Gaige, Connor J.; Stecker, Richard A.; Sunderland, Kyle L.; Mumford, Petey W.

doi:10.3389/fspor.2022.1070477

Cited by 1 publication

(4 citation statements)

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“…Fat oxidation rates during fixed-intensity cycling were not affected by pre-exercise protein ingestion of different quantities compared to fasted exercise. The findings of this study are in line with previous studies [ 15 , 17 , 18 , 21 ]. Exercise in the fasted state, whether performed in a low muscle glycogen state or not, is accompanied with higher fat oxidation rates compared to a CHO-fed state, which is primarily due to the absence of insulin’s effect on suppressing mechanisms involved in lipolysis and beta-oxidation [ 15 ].…”

Section: Discussionsupporting

confidence: 93%

“…Resting energy expenditure was significantly elevated post-exercise, which is a common finding following moderate and high-intensity exercise [ 33 ]. We hypothesized that due to diet-induced thermogenesis following different protein doses, the protein groups would have higher post-exercise REE compared to 0 g. However, no significant differences were observed between the different doses, despite a large effect size in pre- to post-exercise change within the 40 g condition but moderate effect sizes for 0 and 20 g. Findings are somewhat similar compared to previous studies, who demonstrated significantly higher REE following pre-exercise protein compared to CHO-fed, but not compared to fasted [ 17 , 20 , 21 ]. The timing of the post-exercise measurement, might explain some discrepancies.…”

Section: Discussionsupporting

confidence: 70%

“…For example, Ratliff et al . [ 21 ], using a similar protocol, found differences in REE immediately post-exercise (1.5 h following consumption) but not 60 min after exercise, between pre-exercise CHO and protein intake, but not protein compared to fasted the latter time point more reflective of the time of measurement in the current study. Gieske et al .…”

Section: Discussionsupporting

confidence: 52%

“…[ 19 ] also reported that the reduction in energy intake following fasted exercise occurred in conjunction with a decrease in energy expenditure compared to exercise in the fed state, which the authors attribute to higher diet-induced thermogenesis for the fed condition. Interestingly, some studies demonstrated that pre-exercise protein consumption provided higher rates of resting energy expenditure (REE) post-exercise compared to carbohydrates but not to the fasted condition [ 17 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

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The effect of pre-exercise protein intake on substrate metabolism, energy expenditure, and energy intake: a dose–response study

Peeters,

Cook,

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2023

Journal of the International Society of Sports Nutrition

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Background Pre-exercise protein consumption does not seem to influence substrate metabolism during exercise compared to fasted exercise, however it is unclear if the protein dose impacts on this effect. Methods In a randomized, double-blinded within-subject design trial, healthy, active males and females ( n = 15, 25 ± 5 yrs, O2peak: 47.5 ± 8.8 ml/kg/min) completed 1 h of cycling exercise at 60% peak power output 30 min after having consumed either 0, 20, or 40 g of whey protein. Indirect calorimetry was used to measure substrate oxidation during exercise and baseline and post-exercise resting energy expenditure. Blood samples were taken throughout the trials to measure metabolic responses. Free-living food intake post-trial was collected using food diaries. Results Fat oxidation rates during exercise did not differ between the three conditions ( p = 0.19) with small effect sizes between conditions (Cohen’s dz: 0 vs. 20 g = 0.22, 0 vs. 40 g = 0.47, 20 vs. 40 g = 0.27). Serum insulin was higher in the protein groups vs. 0 g ( p < 0.05), whereas non-esterified fatty acids were higher in the 0 g compared to 20 and 40 g ( p < 0.05). Glucose was significantly lower after 15 min of exercise in 20 and 40 g vs. 0 g ( p = 0.01). Resting energy expenditure was elevated post-exercise ( p < 0.001), without an interaction for protein dose ( p = 0.90). Post-trial free-living energy intake was not different between conditions ( p = 0.31), but 24-h energy intake was significantly higher in 40 vs. 0 g ( p = 0.04). Conclusion Protein doses up to 40 g do not seem to impair fat oxidation rates during exercise compared to fasted exercise and could be considered as a nutritional strategy for exercising individuals who struggle to include fasted exercise in their training.

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