Fat Adaptation

Burke L. M., and B. Kiens. "Fat adaptation" for athletic performance - the nail in the coffin? Journal of Applied Physiology 100: 7-8, 2006.

Stellingwerff T, L.L. Spriet, M.J, Watt, N.E. Kimber, M. Hargreaves, J.A. Hawley, and L.M. Burke. Decreased PDH Activation and Glycogenolysis During Exercise Following Fat Adaptation with Carbohydrate Restoration. American Journal of Physiology - Endocrinology and Metabolism 290: E380-E388, 2006.

Burke L.M., B. Kiens, and J.L Ivy. Carbohydrates and fat for training and recovery. Journal of Sports Sciences 22: 15-30, 2004.

Cameron-Smith, D., L.M. Burke, D.J. Angus, R.J Tunstall, G.R. Cox, A. Bonen, J.A Hawley, M. Hargreaves. A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle. American Journal of Clinical Nutrition 77: 313-8, 2003.

Burke L. M., and J. A. Hawley. Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Medicine & Science in Sports & Exercise 34: 1492-1498, 2002.

Stepto L. M., A. L. Carey, H. M. Staudacher, N. K. Cummings, L. M. Burke, and J. A. Hawley. Effect of short-term fat adaptation on high-intensity training. Medicine & Science in Sports & Exercise 34: 449-55, 2002.

Burke L. M., J. A. Hawley, D. J. Angus, G. R. Cox, S. A. Clark, N. K. Cummings, B. Desbrow, and M. Hargreave
s. Adaptations to short-term high-fat diets persist during exercise despite high carbohydrate availability. Medicine & Science in Sports & Exercise 34: 83-91, 2002.

Staudacher H. M., A. L. Carey, N. K. Cummins, J. A. Hawley, and L. M. Burke. Short-term high-fat diet alters substrate utilisation during exercise but not glucose tolerance in highly trained athletes. International Journal Sport Nutrition and Exercise Metabolism 11: 273-86, 2001.

Carey A. L., H. M. Staudacher, N. K. Cummings, N. K, Stepto, V. Nikolopoulos, L. M. Burke, and J. A. Hawley
. Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise. Journal of Applied Physiology 91: 115-22, 2001.

Hawley J. A., L. M. Burke, D. J. Angus, K. E. Fallon, D. T. Martin, and M. A. Febbraio
. Effect of altering substrate availability on metabolism and performance during exercise. British Journal of Nutrition 84: 829-38, 2000.

Burke L. M., D. J. Angus, G. R. Cox, N. K. Cummings, M. A. Febbraio, K. Gawthorn, J. A. Hawley, M. Minehan, D. T. Martin, and M. Hargreaves
. Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling. Journal of Applied Physiology 89: 2413-2421, 2000.


Burke L. M., and B. Kiens. "Fat adaptation" for athletic performance - the nail in the coffin? Journal of Applied Physiology 100: 7-8, 2006.

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Stellingwerff T, L.L. Spriet, M.J, Watt, N.E. Kimber, M. Hargreaves, J.A. Hawley, and L.M. Burke. Decreased PDH Activation and Glycogenolysis During Exercise Following Fat Adaptation with Carbohydrate Restoration. American Journal of Physiology - Endocrinology and Metabolism. 290: E380-E388, 2006.

Five days of a high fat diet while training, followed by 1 day of carbohydrate (CHO) restoration, increases rates of whole-body fat oxidation and decreases CHO oxidation during aerobic cycling. The mechanisms responsible for these shifts in fuel oxidation are unknown, but would involve up and down regulation of key regulatory enzymes in the pathways of skeletal muscle fat and CHO metabolism, respectively. This study measured muscle pyruvate dehydrogenase (PDH) and hormone sensitive lipase (HSL) activities pre- and post 20 min of cycling at 70% of VO2peak and 1 min of sprinting at 150% peak power output (PPO). Estimations of muscle glycogenolysis were made during the initial min of exercise at 70% VO2peak and during the 1 min sprint. Seven male cyclists undertook this exercise protocol on two occasions. For 5 days, subjects consumed in random order either a high-CHO (HCHO) diet (10.3 g(.)kg(-1)(.)day(-1) CHO or ~70% of total energy intake) or an isoenergetic high-fat (FAT-adapt) diet (4.6 g(.)kg(-1)(.)day(-1) FAT or 67% of total energy) while undertaking supervised aerobic endurance training. On day 6 for both treatments, subjects ingested a high CHO diet and rested before their experimental trials on day 7. This CHO restoration resulted in similar resting glycogen contents (FAT-adapt: 873 +/- 121 vs. HCHO: 868 +/- 120 umoles glucosyl units (.)g(-1) dw). However, the respiratory exchange ratio was lower during cycling at 70% VO2 peak in the FAT-adapt trial, which resulted in a ~45% increase and a ~30% decrease in fat and CHO oxidation respectively. PDH activity was lower at rest and throughout exercise at 70% VO2peak (1.69 +/- 0.25 vs 2.39 +/- 0.19 mmol(.)kg(-1) ww(.)min(-1)) and the 1 min sprint in the FAT-adapt compared to HCHO trial. Estimates of glycogenolysis during the first min of exercise at 70% VO2peak and the 1 min sprint were also lower following FAT-adapt (9.1 +/- 1.1 vs 13.4 +/- 2.1 and 37.3 +/- 5.1 vs 50.5 +/- 2.7 glucosyl units(.)kg(-1) dw(.)min(-1)). HSL activity was ~20% higher (P=0.12) during exercise at 70% VO2peak following FAT-adapt. These results indicate that the previously reported decreases in whole body CHO oxidation and increases in fat oxidation following the FAT-adapt protocol are a function of metabolic changes within skeletal muscle. The metabolic signals responsible for the shift in muscle substrate use during cycling at 70% VO2peak remain unclear but lower accumulation of free ADP and AMP following the FAT-adapt trial may be responsible for the decreased glycogenolysis and PDH activation during sprinting.


Burke L.M., B. Kiens, and J.L Ivy. Carbohydrates and fat for training and recovery. Journal of Sports Sciences 22: 15-30, 2004.

An important goal of the athlete's everyday diet is to provide the muscle with substrates to fuel the training programme that will achieve optimal adaptation for performance enhancements. In reviewing the scientific literature on post-exercise glycogen storage since 1991, the following guidelines for the training diet are proposed. Athletes should aim to achieve carbohydrate intakes to meet the fuel requirements of their training programme and to optimize restoration of muscle glycogen stores between workouts. General recommendations can be provided, preferably in terms of grams of carbohydrate per kilogram of the athlete's body mass, but should be fine-tuned with individual consideration of total energy needs, specific training needs and feedback from training performance. It is valuable to choose nutrient-rich carbohydrate foods and to add other foods to recovery meals and snacks to provide a good source of protein and other nutrients. These nutrients may assist in other recovery processes and, in the case of protein, may promote additional glycogen recovery when carbohydrate intake is suboptimal or when frequent snacking is not possible. When the period between exercise sessions is < 8 h, the athlete should begin carbohydrate intake as soon as practical after the first workout to maximize the effective recovery time between sessions. There may be some advantages in meeting carbohydrate intake targets as a series of snacks during the early recovery phase, but during longer recovery periods (24 h) the athlete should organize the pattern and timing of carbohydrate-rich meals and snacks according to what is practical and comfortable for their individual situation. Carbohydrate-rich foods with a moderate to high glycaemic index provide a readily available source of carbohydrate for muscle glycogen synthesis, and should be the major carbohydrate choices in recovery meals. Although there is new interest in the recovery of intramuscular triglyceride stores between training sessions, there is no evidence that diets which are high in fat and restricted in carbohydrate enhance training.


Cameron-Smith, D., L.M. Burke, D.J. Angus, R.J Tunstall, G.R. Cox, A. Bonen, J.A Hawley, and M. Hargreaves. A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle. American Journal of Clinical Nutrition 77: 313-8, 2003.

BACKGROUND: Dietary fatty acids may be important in regulating gene expression. However, little is known about the effect of changes in dietary fatty acids on gene regulation in human skeletal muscle. OBJECTIVE: The objective was to determine the effect of altered dietary fat intake on the expression of genes encoding proteins necessary for fatty acid transport and beta-oxidation in skeletal muscle. DESIGN: Fourteen well-trained male cyclists and triathletes with a mean (+/- SE) age of 26.9 +/- 1.7 y, weight of 73.7 +/- 1.7 kg, and peak oxygen uptake of 67.0 +/- 1.3 mL x kg(-1) x min(-1) consumed either a high-fat diet (HFat: > 65% of energy as lipids) or an isoenergetic high-carbohydrate diet (HCho: 70-75% of energy as carbohydrate) for 5 d in a crossover design. On day 1 (baseline) and again after 5 d of dietary intervention, resting muscle and blood samples were taken. Muscle samples were analyzed for gene expression [fatty acid translocase (FAT/CD36), plasma membrane fatty acid binding protein (FABPpm), carnitine palmitoyltransferase I (CPT I), beta-hydroxyacyl-CoA dehydrogenase (beta-HAD), and uncoupling protein 3 (UCP3)] and concentrations of the proteins FAT/CD36 and FABPpm. RESULTS: The gene expression of FAT/CD36 and beta -HAD and the gene abundance of FAT/CD36 were greater after the HFat than after the HCho diet (P < 0.05). Messenger RNA expression of FABPpm, CPT I, and UCP-3 did not change significantly with either diet. CONCLUSIONS: A rapid and marked capacity for changes in dietary fatty acid availability to modulate the expression of mRNA-encoding proteins is necessary for fatty acid transport and oxidative metabolism. This finding is evidence of nutrient-gene interactions in human skeletal muscle.


Burke L. M. and J. A. Hawley.  Effects of short-term fat adaptation on metabolism and performance of prolonged exercise.  Medicine & Science in Sports & Exercise 34:1492-1498, 2002.

The concept of manipulating an individual's habitual diet before an exercise bout in an attempt to modify patterns of fuel substrate utilisation and enhance subsequent exercise capacity is not new.  Modern studies have focused on nutritional and training strategies aimed to optimise endogenous carbohydrate (CHO) stores while simultaneously maximising the capacity for fat oxidation during continuous, submaximal (60-70% of maximal O 2 uptake [VO 2max ]) exercise.  Such "nutritional periodisation" typically encompasses 5-6 d of a high-fat diet (60-70% E) followed by 1-2 d of high-CHO intake (70-80% E; CHO restoration).  Despite the brevity of the adaptation period, ingestion of a high-fat diet by endurance-trained athletes results in substantially higher rates of fat oxidation and concomitant muscle glycogen sparing during submaximal exercise compared with an isoenergetic high-CHO diet.  Higher rates of fat oxidation during exercise persist even under conditions in which CHO availability is increased, either by having athletes consume a high-CHO meal before exercise and/or ingest glucose solutions during exercise. Yet, despite marked changes in the patterns of fuel utilisation that favour fat oxidation, fat adaptation/CHO restoration strategies do not provide clear benefits to the performance of prolonged endurance exercise.

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Stepto L. M., A. L. Carey, H. M. Staudacher, N. K. Cummings, L. M. Burke, and J. A. Hawley. Effect of short-term fat adaptation on high-intensity training.  Medicine & Science in Sports & Exercise 34: 449-55, 2002.

PURPOSE: To determine the effect of short-term (3-d) fat adaptation on high-intensity exercise training in seven competitive endurance athletes (maximal O2 uptake 5.0 +/- 0.5 L x min(-1), mean +/-SD). METHODS: Subjects consumed a standardized diet on d-0 then, in a randomised cross-over design, either 3-d of high-CHO (11 g x kg(-1)d(-1) CHO, 1 g x kg(-1) x d(-1) fat; HICHO) or an isoenergetic high-fat (2.6 g CHO x kg(-1) x d(-1), 4.6 g FAT x kg(-1) x d(-1); HIFAT) diet separated by an 18-d wash out. On the 1st (d-1) and 4th (d-4) day of each treatment, subjects completed a standardized laboratory training session consisting of a 20-min warm-up at 65% of VO2peak (232 +/- 23W) immediately followed by 8 x 5 min work bouts at 86 +/- 2% of VO2peak (323 +/- 32 W) with 60-s recovery. RESULTS: Respiratory exchange ratio (mean for bouts 1, 4, and 8) was similar on d-1 for HIFAT and HICHO (0.91 +/- 0.04 vs 0.92 +/- 0.03) and on d-4 after HICHO (0.92 +/- 0.03) but fell to 0.85 +/- 0.03 (P < 0.05) on d-4 after HIFAT. Accordingly, the rate of fat oxidation increased from 31 +/- 13 on d-1 to 61 +/- 25 micromol x kg(-1) x min(-1) on d-4 after HIFAT (P < 0.05). Blood lactate concentration was similar on d-1 and d-4 of HICHO and on d-1 of HIFAT (3.5 +/- 0.9 and 3.2 +/- 1.0 vs 3.7 +/- 1.2 mM) but declined to 2.4 +/- 0.5 mM on d-4 after HIFAT (P < 0.05). Ratings of perception of effort (legs) were similar on d-1 for HIFAT and HICHO (14.8 +/- 1.5 vs 14.1 +/- 1.4) and on d-4 after HICHO (13.8 +/- 1.8) but increased to 16.0 +/- 1.3 on d-4 after HIFAT (P < 0.05). CONCLUSIONS: 1) competitive endurance athletes can perform intense interval training during 3-d exposure to a high-fat diet, 2) such exercise elicited high rates of fat oxidation, but 3) compared with a high-carbohydrate diet, training sessions were associated with increased ratings of perceived exertion.

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Burke L. M., J. A. Hawley, D. J. Angus, G. R. Cox, S. A. Clark, N. K. Cummings, B. Desbrow, and M. Hargreaves. Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability. Medicine & Science in Sports & Exercise 34: 83-91, 2002.

PURPOSE: Five days of a high-fat diet produce metabolic adaptations that increase the rate of fat oxidation during prolonged exercise. We investigated whether enhanced rates of fat oxidation during submaximal exercise after 5 d of a high-fat diet would persist in the face of increased carbohydrate (CHO) availability before and during exercise. METHODS: Eight well-trained subjects consumed either a high-CHO (9.3 g x kg(-1) x d(-1) CHO, 1.1 g x kg(-1) x d(-1) fat; HCHO) or an isoenergetic high-fat diet (2.5 g x kg(-1) x d(-1) CHO, 4.3 g x kg(-1) x d(-1) fat; FAT-adapt) for 5 d followed by a high-CHO diet and rest on day 6. On day 7, performance testing (2 h steady-state (SS) cycling at 70% peak O(2) uptake [VO(2peak)] + time trial [TT]) of 7 kJ x kg(-1)) was undertaken after a CHO breakfast (CHO 2 g x kg(-1)) and intake of CHO during cycling (0.8 g x kg(-1) x h(-1)). RESULTS: FAT-adapt reduced respiratory exchange ratio (RER) values before and during cycling at 70% VO(2peak); RER was restored by 1 d CHO and CHO intake during cycling (0.90 +/- 0.01, 0.80 +/- 0.01, 0.91 +/- 0.01, for days 1, 6, and 7, respectively). RER values were higher with HCHO (0.90 +/- 0.01, 0.88 +/- 0.01 (HCHO > FAT-adapt, P < 0.05), 0.95 +/- 0.01 (HCHO > FAT-adapt, P < 0.05)). On day 7, fat oxidation remained elevated (73 +/- 4 g vs 45 +/- 3 g, P < 0.05), whereas CHO oxidation was reduced (354 +/- 11 g vs 419 +/- 13 g, P < 0.05) throughout SS in FAT-adapt versus HCHO. TT performance was similar for both trials (25.53 +/- 0.67 min vs 25.45 +/- 0.96 min, NS). CONCLUSION: Adaptations to a short-term high-fat diet persisted in the face of high CHO availability before and during exercise, but failed to confer a performance advantage during a TT lasting approximately 25 min undertaken after 2 h of submaximal cycling.

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Staudacher H. M., A. L. Carey, N. K. Cummins, J. A . Hawley, and L. M. Burke. Short-term high-fat diet alters substrate utilisation during exercise but not glucose tolerance in highly trained athletes. International Journal Sport Nutrition and Exercise Metabolism 11: 273-86, 2001.

We determined the effect of a high-fat diet and carbohydrate (CHO) restoration on substrate oxidation and glucose tolerance in 7 competitive ultra-endurance athletes (peak oxygen uptake [VO(2peak)] 68 +/- 1 ml x kg(-1) x min(-1); mean +/- SEM). For 6 days, subjects consumed a random order of a high-fat (69% fat; FAT-adapt) or a high-CHO (70% CHO; HCHO) diet, each followed by 1 day of a high-CHO diet. Treatments were separated by an 18-day wash out. Substrate oxidation was determined during submaximal cycling (20 min at 65% VO(2peak)) prior to and following the 6 day dietary interventions. Fat oxidation at baseline was not different between treatments (17.4 +/- 2.1 vs. 16.1 +/- 1.3 g x 20 min(-1) for FAT-adapt and HCHO, respectively) but increased 34% after 6 days of FAT-adapt (to 23.3 +/- 0.9 g x 20 min(-1), p < .05) and decreased 30% after HCHO (to 11.3 +/- 1.4 g x 20 min(-1), p < .05). Glucose tolerance, determined by the area under the plasma [glucose] versus time curve during an oral glucose tolerance (OGTT) test, was similar at baseline (545 +/- 21 vs. 520 +/- 28 mmol x L(-1) x 90 min(-1)), after 5-d of dietary intervention (563 +/- 26 vs. 520 +/-18 mmol x L(-1) x 90 min(-1)) and after 1 d of high-CHO (491 +/- 28 vs. 489 +/- 22 mmol x L(-1) x 90 min(-1) for FAT- adapt and HCHO, respectively). An index of whole-body insulin sensitivity ( S(I), 10000/divided by fasting [glucose] x fasting [insulin] x mean [glucose] during OGTT x mean [insulin] during OGTT) was similar at baseline (15 +/- 2 vs. 17 +/- 5 arbitrary units), after 5-d of dietary intervention (15 +/- 2 vs. 15 +/- 2) and after 24 h of CHO loading (17 +/- 3 vs. 18 +/- 2 for FAT- adapt and HCHO, respectively). We conclude that despite marked changes in the pattern of substrate oxidation during submaximal exercise, short-term adaptation to a high-fat diet does not alter whole-body glucose tolerance or an index of insulin sensitivity in highly-trained individuals.

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Carey A. L., H. M. Staudacher, N. K. Cummings, N. K, Stepto, V. Nikolopoulos, L. M. Burke and J. A. Hawley. Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise.  Journal Applied Physiology 91: 115-22, 2001.

We determined the effect of fat adaptation on metabolism and performance during 5 h of cycling in seven competitive athletes who consumed a standard carbohydrate (CHO) diet for 1 day and then either a high-CHO diet (11 g. kg(-1)x day(-1) CHO, 1 g x kg(-1) x day(-1) fat; HCHO) or an isoenergetic high-fat diet (2.6 g x kg(-1) x day(-1) CHO, 4.6 g x kg(-1) x day(-1) fat; fat-adapt) for 6 days. On day 8, subjects consumed a high-CHO diet and rested. On day 9, subjects consumed a preexercise meal and then cycled for 4 h at 65% peak O(2) uptake, followed by a 1-h time trial (TT). Compared with baseline, 6 days of fat-adapt reduced respiratory exchange ratio (RER) with cycling at 65% peak O(2) uptake [0.78 +/- 0.01 (SE) vs. 0.85 +/- 0.02; P < 0.05]. However, RER was restored by 1 day of high-CHO diet, preexercise meal, and CHO ingestion (0.88 +/- 0.01; P < 0.05). RER was higher after HCHO than fat-adapt (0.85 +/- 0.01, 0.89 +/- 0.01, and 0.93 +/- 0.01 for days 2, 8, and 9, respectively; P < 0.05). Fat oxidation during the 4-h ride was greater (171 +/- 32 vs. 119 +/- 38 g; P < 0.05) and CHO oxidation lower (597 +/- 41 vs. 719 +/- 46 g; P < 0.05) after fat-adapt. Power output was 11% higher during the TT after fat-adapt than after HCHO (312 +/- 15 vs. 279 +/- 20 W; P = 0.11). In conclusion, compared with a high-CHO diet, fat oxidation during exercise increased after fat-adapt and remained elevated above baseline even after 1 day of a high-CHO diet and increased CHO availability. However, this study failed to detect a significant benefit of fat adaptation to performance of a 1-h TT undertaken after 4 h of cycling.

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Hawley J. A., L. M. Burke, D. J. Angus, K. E. Fallon, D. T. Martin and M. A. Febbraio.  Effect of altering substrate availability on metabolism and performance during exercise. British Journal of Nutrition 84: 829-38, 2000.

The purpose of this study was to determine the effect of altering substrate availability on metabolism and performance during intense cycling. Seven highly trained men ingested a random order of three isoenergetic meals 90 min before cycling at 80% maximal oxygen uptake (VO2max) for 20 min (about 310 W), followed by a 600 kJ time trial lasting about 30 min. Meals consisted of either 1.2 g saturated fat/kg body mass (BM) with 3500 U heparin intravenously (HIFAT) to elevate circulating plasma free fatty acid (FA) concentration, 2.5 g carbohydrate/kg BM (CHO) to elevate plasma glucose and insulin concentrations or 2.5 g carbohydrate +20 mg nicotinic acid/kg BM (NA) to suppress lipolysis and reduce free FA concentration. HIFAT elevated free FA concentration (HIFAT 1.3 (sem 0.2), CHO 0.2 (sem 0.1), NA 0.1 (sem 0.1) mm; P < 0.001) lowered the RER (HIFAT 0.94 (sem 0.01), CHO 0.97 (sem 0.01), NA 0.98 (sem 0.01); P < 0.01) and increased the rate of fat oxidation (HIFAT 24 (sem 3), CHO 12 (sem 2), NA 8 (sem 3) micromol/kg per min; P < 0.01) during the 20 min ride. Marked differences in fat availability and fuel utilisation, however, had little effect on performance in the subsequent time trial (HIFAT 320 (sem 16), CHO 324 (sem 15), NA 315 (sem 13) W). We conclude: (1) increased fat availability during intense cycling increases the rate of fat oxidation; but (2) the reduction in the rate of carbohydrate oxidation in the presence of high circulating plasma free FA is unlikely to enhance intense exercise performance lasting about 1 h; (3) substrate selection during intense (about 80% VO2max) exercise is dominated by carbohydrate oxidation.


Burke L. M., D. J. Angus, G. R. Cox, N. K. Cummings, M. A. Febbraio, K. Gawthorn, J. A. Hawley, M. Minehan, D. T. Martin, and M. Hargreaves. Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged exercise.  Journal of Applied Physiology 89: 2413-2421, 2000.

For 5 days, eight well-trained cyclists consumed a random order of a high-carbohydrate (CHO) diet (9.6 g. kg(-1). day(-1) CHO, 0.7 g. kg(-1). day(-1) fat; HCHO) or an isoenergetic high-fat diet (2.4 g. kg(-1). day(-1) CHO, 4 g. kg(-1). day(-1) fat; Fat-adapt) while undertaking supervised training. On day 6, subjects ingested high CHO and rested before performance testing on day 7 [2 h cycling at 70% maximal O(2) consumption (SS) + 7 kJ/kg time trial (TT)]. With Fat-adapt, 5 days of high-fat diet reduced respiratory exchange ratio (RER) during cycling at 70% maximal O(2) consumption; this was partially restored by 1 day of high CHO [0.90 +/- 0.01 vs. 0.82 +/- 0.01 (P < 0.05) vs. 0.87 +/- 0.01 (P < 0.05), for day 1, day 6, and day 7, respectively]. Corresponding RER values on HCHO trial were [0. 91 +/- 0.01 vs. 0.88 +/- 0.01 (P < 0.05) vs. 0.93 +/- 0.01 (P < 0. 05)]. During SS, estimated fat oxidation increased [94 +/- 6 vs. 61 +/- 5 g (P < 0.05)], whereas CHO oxidation decreased [271 +/- 16 vs. 342 +/- 14 g (P < 0.05)] for Fat-adapt compared with HCHO. Tracer-derived estimates of plasma glucose uptake revealed no differences between treatments, suggesting muscle glycogen sparing accounted for reduced CHO oxidation. Direct assessment of muscle glycogen utilization showed a similar order of sparing (260 +/- 26 vs. 360 +/- 43 mmol/kg dry wt; P = 0.06). TT performance was 30.73 +/- 1.12 vs. 34.17 +/- 2.48 min for Fat-adapt and HCHO (P = 0.21). These data show significant metabolic adaptations with a brief period of high-fat intake, which persist even after restoration of CHO availability. However, there was no evidence of a clear benefit of fat adaptation to cycling performance.

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