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Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation.
Margolis, LM, Wilson, MA, Whitney, CC, Carrigan, CT, Murphy, NE, Hatch, AM, Montain, SJ, Pasiakos, SM
Metabolism: clinical and experimental. 2019;:1-8
Abstract
BACKGROUND Initiating aerobic exercise with low muscle glycogen content promotes greater fat and less endogenous carbohydrate oxidation during exercise. However, the extent exogenous carbohydrate oxidation increases when exercise is initiated with low muscle glycogen is unclear. PURPOSE Determine the effects of muscle glycogen content at the onset of exercise on whole-body and muscle substrate metabolism. METHODS Using a randomized, crossover design, 12 men (mean ± SD, age: 21 ± 4 y; body mass: 83 ± 11 kg; VO2peak: 44 ± 3 mL/kg/min) completed 2 cycle ergometry glycogen depletion trials separated by 7-d, followed by a 24-h refeeding to elicit low (LOW; 1.5 g/kg carbohydrate, 3.0 g/kg fat) or adequate (AD; 6.0 g/kg carbohydrate, 1.0 g/kg fat) glycogen stores. Participants then performed 80 min of steady-state cycle ergometry (64 ± 3% VO2peak) while consuming a carbohydrate drink (95 g glucose +51 g fructose; 1.8 g/min). Substrate oxidation (g/min) was determined by indirect calorimetry and 13C. Muscle glycogen (mmol/kg dry weight), pyruvate dehydrogenase (PDH) activity, and gene expression were assessed in muscle. RESULTS Initiating steady-state exercise with LOW (217 ± 103) or AD (396 ± 70; P < 0.05) muscle glycogen did not alter exogenous carbohydrate oxidation (LOW: 0.84 ± 0.14, AD: 0.87 ± 0.16; P > 0.05) during exercise. Endogenous carbohydrate oxidation was lower and fat oxidation was higher in LOW (0.75 ± 0.29 and 0.55 ± 0.10) than AD (1.17 ± 0.29 and 0.38 ± 0.13; all P < 0.05). Before and after exercise PDH activity was lower (P < 0.05) and transcriptional regulation of fat metabolism (FAT, FABP, CPT1a, HADHA) was higher (P < 0.05) in LOW than AD. CONCLUSION Initiating exercise with low muscle glycogen does not impair exogenous carbohydrate oxidative capacity, rather, to compensate for lower endogenous carbohydrate oxidation acute adaptations lead to increased whole-body and skeletal muscle fat oxidation.
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Weight gain is associated with changes in neural response to palatable food tastes varying in sugar and fat and palatable food images: a repeated-measures fMRI study.
Yokum, S, Stice, E
The American journal of clinical nutrition. 2019;(6):1275-1286
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Abstract
BACKGROUND Emerging data suggest that weight gain is associated with changes in neural response to palatable food tastes and palatable food cues, which may serve to maintain overeating. OBJECTIVE We investigated whether weight gain is associated with neural changes in response to tastes of milkshakes varying in fat and sugar content and palatable food images. METHODS We compared changes in neural activity between initially healthy-weight adolescents who gained weight (n = 36) and those showing weight stability (n = 31) over 2-3 y. RESULTS Adolescents who gained weight compared with those who remained weight stable showed decreases in activation in the postcentral gyrus, prefrontal cortex, insula, and anterior cingulate cortex, and increases in activation in the parietal lobe, posterior cingulate cortex, and inferior frontal gyrus in response to a high-fat/low-sugar compared with low-fat/low-sugar milkshake. Weight gainers also showed greater decreases in activation in the anterior insula and lateral orbitofrontal cortex in response to a high-fat/high-sugar compared with low-fat/low-sugar milkshake than those who remained weight stable. No group differences emerged in response to a low-fat/high-sugar compared with a low-fat/low-sugar milkshake. Weight gainers compared with those who remained weight stable showed greater decreases in activation in the middle temporal gyrus and increases in cuneus activation in response to appetizing compared with unappetizing food pictures. The significant interactions were partially driven by group differences in baseline responsivity and by opposite changes in neural activation in adolescents who remained weight stable. CONCLUSIONS Data suggest that weight gain is associated with a decrease in responsivity of regions associated with taste and reward processing to palatable high-fat- and high-fat/high-sugar food tastes. Data also suggest that avoiding weight gain increases taste sensitivity, which may prevent future excessive weight gain.This trial was registered at clinicaltrials.gov as NCT01949636.
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Effect of modified fasting therapy on body weight, fat and muscle mass, and blood chemistry in patients with obesity.
Kim, KW, Song, MY, Chung, SH, Chung, WS
Journal of traditional Chinese medicine = Chung i tsa chih ying wen pan. 2016;(1):57-62
Abstract
OBJECTIVE The aim of this study was to investigate the effects and safety of modified fasting therapy using fermented medicinal herbs and exercise on body weight, fat and muscle mass, and blood chemistry in obese subjects. METHODS Twenty-six patients participated in a 14-day fast, during which they ingested a supplement made from fermented medicinal herbs and carbohydrates (intake: 400-600 kcal/d). The schedule included 7 prefasting relief days and 14 days of stepwise reintroduction of food. The patients also took part in an exercise program that incorporated Qigong, weight training, and walking exercises. The efficacy of treatments was observed by assessing body fat mass and muscle mass, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), cholesterol, and triglycerides in each study period. Specific symptoms or side effects were reported. RESULTS Body weight and body fat mass both decreased significantly by (5.16 ± 0.95) and (3.89 ± 0.79) kg (both P < 0.05), while muscle mass decreased by an average of (0.26 ± 0.22) kg, without statistical significance. ALT levels were significantly decreased (P < 0.05), while AST levels decreased without statistical significance (P = 0.052). The levels of total cholesterol and triglycerides were also significantly decreased (both P < 0.05). There were few adverse events except for mild dizziness, which did not affect everyday living. CONCLUSION These results suggest that modified fasting therapy using fermented medicinal herbs and exercise could be effective and safe on obese patients.
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The influence of exogenous fat and water on lumbar spine bone mineral density in healthy volunteers.
Kim, KN, Kim, BT, Kim, KM, Park, SB, Joo, NS, Je, SH, Kim, YS, Lee, DJ
Yonsei medical journal. 2012;(2):289-93
Abstract
PURPOSE Changes in human body composition can affect the accuracy of spine bone mineral density (BMD) measurements. The purpose of this study was to evaluate whether fat and water in the soft tissue of the abdomen influence lumbar spine BMD measurements obtained using dual energy X-ray absorptiometry (DXA). MATERIALS AND METHODS Duplicate BMD measurements were carried out on healthy volunteers (10 men and 10 women) and the Hologic anthropomorphic spine phantom had on the same day before and after placement of following 3 materials in the abdominal area: lard 900 g, 1.5 cm thick; oil 1.4 liters in a vinyl bag; and water 1.2 liters in a vinyl bag. RESULTS In the case of human participants, following the placement of exogenous water to mimic extracellular fluid (ECF), there was a significant decrease in lumbar spine BMD (-0.012 g/cm², p=0.006), whereas the placement of exogenous lard and oil to mimic abdominal fat produced a slight increase in lumbar spine BMD (0.006 g/cm², p=0.301; 0.008 g/cm², p=0.250, respectively). The average percentage of lumbar spine BMD change with and without exogenous lard, oil, and water showed increase of 0.51%, and 0.67%, and decrease of 1.02%, respectively. Using the phantom, BMD decreased with the placement of both lard (-0.002 g/cm², p=0.699) and water (-0.006 g/cm², p=0.153); however, there was no difference in BMD after oil placement. CONCLUSION These results suggest that in cases where changes in fat and ECF volume are similar, ECF exerts a greater influence than fat on DXA lumbar BMD measurements.
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Endotoxin increase after fat overload is related to postprandial hypertriglyceridemia in morbidly obese patients.
Clemente-Postigo, M, Queipo-Ortuño, MI, Murri, M, Boto-Ordoñez, M, Perez-Martinez, P, Andres-Lacueva, C, Cardona, F, Tinahones, FJ
Journal of lipid research. 2012;(5):973-978
Abstract
The low-grade inflammation observed in obesity has been associated with a high-fat diet, though this relation is not fully understood. Bacterial endotoxin, produced by gut microbiota, may be the linking factor. However, this has not been confirmed in obese patients. To study the relationship between a high-fat diet and bacterial endotoxin, we analyzed postprandial endotoxemia in morbidly obese patients after a fat overload. The endotoxin levels were determined in serum and the chylomicron fraction at baseline and 3 h after a fat overload in 40 morbidly obese patients and their levels related with the degree of insulin resistance and postprandial hypertriglyceridemia. The morbidly obese patients with the highest postprandial hypertriglyceridemia showed a significant increase in lipopolysaccharide (LPS) levels in serum and the chylomicron fraction after the fat overload. Postprandial chylomicron LPS levels correlated positively with the difference between postprandial triglycerides and baseline triglycerides. There were no significant correlations between C-reactive protein (CRP) and LPS levels. The main variables contributing to serum LPS levels after fat overload were baseline and postprandial triglyceride levels but not glucose or insulin resistance. Additionally, superoxide dismutase activity decreased significantly after the fat overload. Postprandial LPS increase after a fat overload is related to postprandial hypertriglyceridemia but not to degree of insulin resistance in morbidly obese patients.
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Elevated n-3 fatty acids in a high-fat diet attenuate the increase in PDH kinase activity but not PDH activity in human skeletal muscle.
Turvey, EA, Heigenhauser, GJ, Parolin, M, Peters, SJ
Journal of applied physiology (Bethesda, Md. : 1985). 2005;(1):350-5
Abstract
We tested the hypothesis that a high-fat diet (75% fat; 5% carbohydrates; 20% protein), for which 15% of the fat content was substituted with n-3 fatty acids, would not exhibit the diet-induced increase in pyruvate dehydrogenase kinase (PDK) activity, which is normally observed in human skeletal muscle. The fat content was the same in both the regular high-fat diet (HF) and in the n-3-substituted diet (N3). PDK activity increased after both high-fat diets, but the increase was attenuated after the N3 diet (0.051 +/- 0.007 and 0.218 +/- 0.047 min(-1) for pre- and post-HF, respectively; vs. 0.073 +/- 0.016 and 0.133 +/- 0.032 min(-1) for pre- and post-N3, respectively). However, the active form of pyruvate dehydrogenase (PDHa) activity decreased to a similar extent in both conditions (0.93 +/- 0.17 and 0.43 +/- 0.09 mmol/kg wet wt pre- and post-HF; vs. 0.87 +/- 0.19 and 0.39 +/- 0.05 mmol/kg wet wt pre- and post-N3, respectively). This suggested that the difference in PDK activity did not affect PDHa activation in the basal state, and it was regulated by intramitochondrial effectors, primarily muscle pyruvate concentration. Muscle glycogen content was consistent throughout the study, before and after both diet conditions, whereas muscle glucose-6-phosphate, glycerol-3-phosphate, lactate, and pyruvate were decreased after the high-fat diets. Plasma triglycerides decreased after both high-fat diets but decreased to a greater extent after the N3, whereas plasma free fatty acids increased after both diets, but to a lesser extent after the N3. In summary, PDK activity is decreased after a high-fat diet that is rich in n-3 fatty acids, although PDHa activity was unaltered. In addition, our data demonstrated that the hypolipidemic effect of n-3 fatty acids occurs earlier (3 days) than previously reported and is evident even when the diet has 75% of its total energy derived from fat.
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Increasing dietary palmitic acid decreases fat oxidation and daily energy expenditure.
Kien, CL, Bunn, JY, Ugrasbul, F
The American journal of clinical nutrition. 2005;(2):320-6
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Abstract
BACKGROUND Oleic acid (OA) is oxidized more rapidly than is palmitic acid (PA). OBJECTIVE We hypothesized that changing the dietary intakes of PA and OA would affect fatty acid oxidation and energy expenditure. DESIGN A double-masked trial was conducted in 43 healthy young adults, who, after a 28-d, baseline, solid-food diet (41% of energy as fat, 8.4% as PA, and 13.1% as OA), were randomly assigned to one of two 28-d formula diets: high PA (40% of energy as fat, 16.8% as PA, and 16.4% as OA; n = 21) or high OA (40% of energy as fat, 1.7% as PA, and 31.4% as OA; n = 22). Differences in the change from baseline were evaluated by analysis of covariance. RESULTS In the fed state, the respiratory quotient was lower (P = 0.01) with the high OA (0.86 +/- 0.01) than with the high-PA (0.89 +/- 0.01) diet, and the rate of fat oxidation was higher (P = 0.03) with the high-OA (0.0008 +/- 0.0001) than with the high-PA (0.0005 +/- 0.0001 mg . kg fat-free mass(-1) . min(-1)) diet. Resting energy expenditure in the fed and fasting states was not significantly different between groups. Change in daily energy expenditure in the high-OA group (9 +/- 60 kcal/d) was significantly different from that in the high-PA group (-214 +/- 69 kcal/d; P = 0.02 or 0.04 when expressed per fat-free mass). CONCLUSIONS Increases in dietary PA decrease fat oxidation and daily energy expenditure, whereas decreases in PA and increases in OA had the opposite effect. Increases in dietary PA may increase the risk of obesity and insulin resistance.
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Effects of growth hormone-releasing hormone on bone turnover in human immunodeficiency virus-infected men with fat accumulation.
Koutkia, P, Canavan, B, Breu, J, Grinspoon, S
The Journal of clinical endocrinology and metabolism. 2005;(4):2154-60
Abstract
GHRH is a potentially appealing strategy to simultaneously improve fat distribution and increase bone turnover in HIV-infected patients. We investigated the effects of GHRH (1 mg sc twice a day over 12 wk) in 31 HIV-infected men with abdominal fat accumulation (age 46 +/- 1 yr, body mass index 26.2 +/- 0.6 kg/m2) in a randomized, double-blind, placebo-controlled study. We previously reported significant effects of GHRH on IGF-I and truncal fat. In this study, we assessed whether GHRH increased markers of bone turnover. At baseline, 32% of our subjects (n = 10) demonstrated a bone density Z score less than -1.0 sd and greater than or equal to -2.5 sd, and 3% (n = 1) demonstrated a Z score of less than -2.5 sd. IGF-I correlated with N-terminal telopeptide (NTx) (r = 0.49, P = 0.005) and tended to correlate with C-terminal telopeptide (CTx) (r = 0.35, P = 0.06) at baseline. Of the bone resorption markers, CTx increased significantly (0.16 +/- 0.07 vs. -0.03 +/- 0.03 ng/ml, GHRH vs. placebo, P = 0.02), and NTx tended to increase in response to GHRH (2.8 +/- 1.4 vs. -0.5 +/- 1.0 nm bone collagen equivalent, GHRH vs. placebo, P = 0.07). Of the bone formation markers, N-terminal propeptide of type 1 procollagen increased (14.6 +/- 9 vs. -6.8 +/- 3.1 microg/liter, GHRH vs. placebo, P = 0.03) and osteocalcin tended to increase (8.4 +/- 3.0 vs. 2.0 +/- 1.6 ng/ml, GHRH vs. placebo, P = 0.06) in response to GHRH. The calciotropic hormones, calcium and phosphorus, did not change significantly. The change in IGF-I correlated with the change in NTx (r = 0.45, P = 0.02), CTx (r = 0.38, P = 0.05), and osteocalcin (r = 0.55, P = 0.002). GHRH improves fat distribution and bone metabolism in men with HIV-related fat accumulation. Long-term studies are needed to determine whether the stimulatory effects of GHRH on bone turnover will translate into increased bone density in this population.
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Enhanced fat oxidation through physical activity is associated with improvements in insulin sensitivity in obesity.
Goodpaster, BH, Katsiaras, A, Kelley, DE
Diabetes. 2003;(9):2191-7
Abstract
Skeletal muscle insulin resistance entails dysregulation of both glucose and fatty acid metabolism. This study examined whether a combined intervention of physical activity and weight loss influences fasting rates of fat oxidation and insulin-stimulated glucose disposal. Obese (BMI >30 kg/m(2)) volunteers (9 men and 16 women) without diabetes, aged 39 +/- 4 years, completed 16 weeks of moderate-intensity physical activity combined with caloric reduction. Body composition was determined by dual-energy X-ray absorptiometry and computed tomography. Glucose disposal rates (R(d)) were measured during euglycemic hyperinsulinemia (40 mU x m(-2) x min(-1)), and substrate oxidation was determined via indirect calorimetry. Fat mass and regional fat depots were reduced and VO(2max) improved by 19%, from 38.8 +/- 1.2 to 46.0 +/- 1.0 ml x kg fat-free mass (FFM)(-1) x min(-1) (P < 0.05). Insulin sensitivity improved 49 +/- 10% (6.70 +/- 0.40 to 9.51 +/- 0.51 mg x min(-1) x kg FFM(-1); P < 0.05). Rates of fat oxidation following an overnight fast increased (1.16 +/- 0.06 to 1.36 +/- 0.05 mg x min(-1) x kg FFM(-1); P < 0.05), and the proportion of energy derived from fat increased from 38 to 52%. The strongest predictor of the improved insulin sensitivity was enhanced fasting rates of fat oxidation, accounting for 52% of the variance. In conclusion, exercise combined with weight loss enhances postabsorptive fat oxidation, which appears to be a key aspect of the improvement in insulin sensitivity in obesity.
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Effect of exercise training at different intensities on fat metabolism of obese men.
van Aggel-Leijssen, DP, Saris, WH, Wagenmakers, AJ, Senden, JM, van Baak, MA
Journal of applied physiology (Bethesda, Md. : 1985). 2002;(3):1300-9
Abstract
The present study investigated the effect of exercise training at different intensities on fat oxidation in obese men. Twenty-four healthy male obese subjects were randomly divided in either a low- [40% maximal oxygen consumption (VO(2 max))] or high-intensity exercise training program (70% VO(2 max)) for 12 wk, or a non-exercising control group. Before and after the intervention, measurements of fat metabolism at rest and during exercise were performed by using indirect calorimetry, [U-(13)C]palmitate, and [1,2-(13)C]acetate. Furthermore, body composition and maximal aerobic capacity were measured. Total fat oxidation did not change at rest in any group. During exercise, after low-intensity exercise training, fat oxidation was increased by 40% (P < 0.05) because of an increased non-plasma fatty acid oxidation (P < 0.05). High-intensity exercise training did not affect total fat oxidation during exercise. Changes in fat oxidation were not significantly different among groups. It was concluded that low-intensity exercise training in obese subjects seemed to increase fat oxidation during exercise but not at rest. No effect of high-intensity exercise training on fat oxidation could be shown.