Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation

Margolis, Lee M.; Wilson, Marques A.; Whitney, Claire; Carrigan, Christopher T.; Murphy, Nancy; Hatch, Adrienne M.; Montain, Scott J.; Pasiakos, Stefan M.

doi:10.1016/j.metabol.2019.05.003

Cited by 30 publications

(53 citation statements)

References 41 publications

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“…Since the magnitude of fat oxidation during physical activity seems to depend on insulin (34) and glycogen levels (48) , it can be speculated that the observed effects of a higher ET on relative fat balance would be more pronounced, when physical activity sessions are performed in a fasted state, for example, before breakfast.…”

Section: Discussionmentioning

confidence: 99%

Impact of energy turnover on fat balance in healthy young men during energy balance, energetic restriction and overfeeding

et al. 2019

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Body weight control is thought to be improved when physical activity and energy intake are both high (high energy turnover (ET)). The aim of the present study was to investigate the short-term impact of ET on fat balance during zero energy balance (EB), energetic restriction (ER) and overfeeding (OF). In a randomised crossover study, nine healthy men (BMI: 23·0 (SD 2·1) kg/m2, 26·6 (SD 3·5) years) passed 3 × 3 d in a metabolic chamber: three levels of ET (low, medium and high; physical activity level = 1·3−1·4, 1·5−1·6 and 1·7−1·8) were performed at zero EB, ER and OF (100, 75 and 125 % of individual energy requirement). Different levels of ET were obtained by walking (4 km/h) on a treadmill (0, 165 and 330 min). Twenty-four-hour macronutrient oxidation and relative macronutrient balance (oxidation relative to intake) was calculated, and NEFA, 24-h insulin and catecholamine secretion were analysed as determinants of fat oxidation. During EB and OF, 24-h fat oxidation increased with higher ET. This resulted in a higher relative fat balance at medium ET (EB: +17 %, OF: +14 %) and high ET (EB: +23 %, OF: +17 %) compared with low ET (all P < 0·05). In contrast, ER led to a stimulation of 24-h fat oxidation irrespective of ET (no differences in relative fat balance between ET levels, P > 0·05). In conclusion, under highly controlled conditions, a higher ET improved relative fat balance in young healthy men during OF and EB compared with a sedentary state.

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Section: Discussionmentioning

confidence: 99%

Impact of energy turnover on fat balance in healthy young men during energy balance, energetic restriction and overfeeding

et al. 2019

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“…Glucose transport into the cell does not appear to be altered by short-term LCHF diets. Work from our laboratory showed that consuming a LCHF (16% carbohydrate, 72% fat) versus high-carbohydrate (65% carbohydrate, 25% fat) diet for 24 h after performing an exhaustive exercise bout to elicit low or adequate glycogen stores, respectively, did not alter exogenous carbohydrate oxidation during 80 min of steady-state exercise while consuming a carbohydrate drink (95 g glucose and 51 g fructose; 1.8 g/min) [42]. These findings were supported by a similar expression of GLUT4 and hexokinase mRNA before and after the exercise bout in both groups [42].…”

Section: Glucose Transportmentioning

confidence: 96%

“…Work from our laboratory showed that consuming a LCHF (16% carbohydrate, 72% fat) versus high-carbohydrate (65% carbohydrate, 25% fat) diet for 24 h after performing an exhaustive exercise bout to elicit low or adequate glycogen stores, respectively, did not alter exogenous carbohydrate oxidation during 80 min of steady-state exercise while consuming a carbohydrate drink (95 g glucose and 51 g fructose; 1.8 g/min) [42]. These findings were supported by a similar expression of GLUT4 and hexokinase mRNA before and after the exercise bout in both groups [42]. Burke et al [4] similarly showed that plasma-derived glucose disposal was unchanged during exercise after 5 days of a LCHF (19% carbohydrate, 68% fat) versus high-carbohydrate (74% carbohydrate, 13% fat) diet and one day of high-carbohydrate feeding to restore muscle glycogen concentrations.…”

Section: Glucose Transportmentioning

confidence: 96%

“…Twelve weeks of a LCHF diet (20% carbohydrate, 60% fat) plus endurance training in rats elevated FAT/CD36 mRNA compared to a LCHF diet alone [74]. In humans, one day of LCHF (16% carbohydrate, 72% fat) versus high-carbohydrate (65% carbohydrate, 25% fat) feeding after an exhaustive exercise bout to deplete muscle glycogen increased FAT/CD36 and FABP mRNA expression at rest and after 80 min of steady-state exercise [42]. Five days of LCHF (<20% carbohydrate, >65% fat) versus high-carbohydrate (70-75% carbohydrate, <15% fat) feeding in well-trained cyclists similarly increased resting FAT/CD36 mRNA and protein content, though resting FABP protein content was unchanged in these individuals [26].…”

Section: Fatty Acid Uptakementioning

confidence: 96%

“…Rates of carbohydrate oxidation are largely controlled by PDH activity, which is attenuated at rest and during exercise following LCHF feeding [42,49,50]. These LCHF diet-mediated decreases in PDH activity may impair the use of available carbohydrate for energy production during high-intensity exercise.…”

Section: Pdh Activitymentioning

confidence: 99%

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Intramuscular Mechanisms Mediating Adaptation to Low-Carbohydrate, High-Fat Diets during Exercise Training

Howard

Margolis

2020

Nutrients

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Interest in low-carbohydrate, high-fat (LCHF) diets has increased over recent decades given the theorized benefit of associated intramuscular adaptations and shifts in fuel utilization on endurance exercise performance. Consuming a LCHF diet during exercise training increases the availability of fat (i.e., intramuscular triglyceride stores; plasma free fatty acids) and decreases muscle glycogen stores. These changes in substrate availability increase reliance on fat oxidation for energy production while simultaneously decreasing reliance on carbohydrate oxidation for fuel during submaximal exercise. LCHF diet-mediated changes in substrate oxidation remain even after endogenous or exogenous carbohydrate availability is increased, suggesting that the adaptive response driving changes in fat and carbohydrate oxidation lies within the muscle and persists even when the macronutrient content of the diet is altered. This narrative review explores the intramuscular adaptations underlying increases in fat oxidation and decreases in carbohydrate oxidation with LCHF feeding. The possible effects of LCHF diets on protein metabolism and post-exercise muscle remodeling are also considered.

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Carbohydrate supplementation: a critical review of recent innovations

Baur

Saunders

2020

Eur J Appl Physiol

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Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation

Cited by 30 publications

References 41 publications

Impact of energy turnover on fat balance in healthy young men during energy balance, energetic restriction and overfeeding

Impact of energy turnover on fat balance in healthy young men during energy balance, energetic restriction and overfeeding

Intramuscular Mechanisms Mediating Adaptation to Low-Carbohydrate, High-Fat Diets during Exercise Training

Carbohydrate supplementation: a critical review of recent innovations

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