Low-carbohydrate Meal Research Articles

Subjects with high fasting insulin also have higher postprandial GLP-1 and glucagon levels than controls with lower insulin

Little is known about postprandial release of serum ghrelin, glucagon, and glucagon-like peptide-1 (GLP-1) in relation with differing fasting insulin levels. We hypothesized that these hormones are affected by insulin resistance, and hence, we compared different postprandial responses of GLP-1, glucagon, and ghrelin in subjects with relatively high (RHI) or relatively low (RLI) fasting insulin levels. The trial was a randomized crossover study with 4 different meal conditions. Fourteen nonobese or obese, healthy, men and 14 women were randomly assigned to the order of supervised intake of a 750 kcal drink with the same protein contents but with 20 energy-percent (E%) or 55 E% from carbohydrates, and the remaining energy from fat. Participants were also randomized to consume the drinks as 1 large beverage or as five 150-kcal portions every 30 minutes. The 28 subjects were divided into 2 equally sized groups based on fasting insulin levels. Statistics were done with general linear mixed model. Fasting insulin levels were 3-fold higher in the group with RHI compared with the RLI group (RHI: 1004 ± 510 pg/mL, RLI: 324 ± 123 pg/mL, P < .0005). Serum GLP-1 was highest in the RHI group after both single meals and after 5 drinks and following high- and low-carbohydrate meals (both P ≤ .002), and this was the case also for glucagon levels (both P ≤ .018), whereas ghrelin levels did not differ between groups. Thus, subjects with RHI displayed both higher postprandial serum GLP-1 and glucagon than the participants with RLI, suggesting that glucagon could play a role in the advent of dysglycemia by insulin resistance.

“Train-High Sleep-Low” Dietary Periodization Does Not Alter Ventilatory Strategies During Cycling Exercise

Objective: The purpose of this study was to investigate the effects of “train-high sleep-low” (THSL) dietary periodization on ventilatory strategies during cycling exercise at submaximal and maximal intensities. Method: In a randomized crossover design, 8 trained men [age (mean ± SEM) = 28 ± 1 y; peak oxygen uptake = 56.8 ± 2.4 mL kg−1 min−1] completed two glycogen-depleting protocols on a cycle ergometer on separate days, with the cycling followed by a low carbohydrate (CHO) meal and beverages containing either no additional CHO (THSL) or beverages containing 1.2 g kg−1 CHO [traditional CHO replacement (TRAD)]. The following morning, participants completed 4 minutes of cycling below (Stage 1), at (Stage 2), and above (Stage 3) gas exchange threshold, followed by a 5-km time trial. Results: Timetrial performance was significantly faster in TRAD compared to THSL (8.7 ± 0.3 minutes and 9.0 ± 0.3 minutes, respectively; p = 0.02). No differences in ventilation, tidal volume, or carbon dioxide production occurred between conditions at any exercise intensity (p > 0.05). During Stage 1, oxygen uptake was 37.9 ± 1.5 mL kg−1 min−1 in the TRAD condition and 39.6 ± 1.8 mL kg−1 min−1 in THSL (p = 0.05). During Stage 2, VO2 was 44.6 ± 1.7 mL kg−1 min−1 in the TRAD condition and 47.0 ± 1.9 mL kg−1 min−1 in THSL (p = 0.07). No change in operating lung volume was detected between dietary conditions (p > 0.05). Conclusions: THSL impairs performance following the dietary intervention, but this occurs with no alteration of ventilatory measures.

Acute effect of equicaloric meals varying in glycemic index and glycemic load on arterial stiffness and glycemia in healthy adults: a randomized crossover trial.

Dietary carbohydrate quality and quantity fluctuate but it is unknown which attribute takes precedence in vascular health preservation. We investigated all four permutations of glycemic index (GI) and glycemic load (GL) on acute vascular and glycemic responses. Twenty-one healthy adults were screened for this crossover trial. Seventeen (8 M:9 F; 26.7 ± 12.3 y; BMI 22.2 ± 2.8 kg/m2) entered randomization and completed the study, receiving four isocaloric meals, varying in GI and GL, in random order at least 3 days apart. The four meals included either chickpeas (GI = 28, GL = 14, 50 g available carbohydrates (CHO)), a small potato portion (GI = 85, GL = 14, CHO = 17 g), pasta (GI = 45, GL = 42, CHO = 94 g) or a large potato portion (GI = 85, GL = 42, CHO = 50 g) as the source of carbohydrate. Augmentation index (AIx) and central and peripheral blood pressure were measured fasting, 1, 2, 3, and 4 h post-consumption. Capillary blood glucose was analyzed fasting, 15, 30, 45, 60, 90, 120, 180, and 240 min. A reduction in AIx from baseline was observed 4 h following the chickpeas (low GI-low GL) (p = 0.046). The incremental area under blood glucose curves were significantly higher 2 h post-consumption following high compared with low GL meals (p < 0.001). Despite doubling carbohydrates, there was no difference in glycemic response between the large potato (high GI-high GL) and the pasta (low GI-high GL) meals. No significant differences in AIx or blood pressure were seen between meals. Low GI, low-carbohydrate meals may support a healthy vascular tone. Varying meal GI and GL results in different glycemic profiles, which are not necessarily predicted by carbohydrate content. Further investigations on cardiometabolic profiles to meals varying in GI and GL are warranted.

Post-Exercise Carbohydrate-Energy Replacement Attenuates Insulin Sensitivity and Glucose Tolerance the Following Morning in Healthy Adults.

The carbohydrate deficit induced by exercise is thought to play a key role in increased post-exercise insulin action. However, the effects of replacing carbohydrate utilized during exercise on postprandial glycaemia and insulin sensitivity are yet to be determined. This study therefore isolated the extent to which the insulin-sensitizing effects of exercise are dependent on the carbohydrate deficit induced by exercise, relative to other exercise-mediated mechanisms. Fourteen healthy adults performed a 90-min run at 70% max starting at 1600–1700 h before ingesting either a non-caloric artificially-sweetened placebo solution (CHO-DEFICIT) or a 15% carbohydrate solution (CHO-REPLACE; 221.4 ± 59.3 g maltodextrin) to precisely replace the measured quantity of carbohydrate oxidized during exercise. The alternate treatment was then applied one week later in a randomized, placebo-controlled, and double-blinded crossover design. A standardized low-carbohydrate evening meal was consumed in both trials before overnight recovery ahead of a two-hour oral glucose tolerance test (OGTT) the following morning to assess glycemic and insulinemic responses to feeding. Compared to the CHO-DEFICIT condition, CHO-REPLACE increased the incremental area under the plasma glucose curve by a mean difference of 68 mmol·L−1 (95% CI: 4 to 132 mmol·L−1; p = 0.040) and decreased the Matsuda insulin sensitivity index by a mean difference of −2 au (95% CI: −1 to −3 au; p = 0.001). This is the first study to demonstrate that post-exercise feeding to replaceme the carbohydrate expended during exercise can attenuate glucose tolerance and insulin sensitivity the following morning. The mechanism through which exercise improves insulin sensitivity is therefore (at least in part) dependent on carbohydrate availability and so the day-to-day metabolic health benefits of exercise might be best attained by maintaining a carbohydrate deficit overnight.

A randomized cross-over study of the effects of macronutrient composition and meal frequency on GLP-1, ghrelin and energy expenditure in humans

ObjectiveLittle is known about human postprandial increase of energy expenditure and satiety-associated hormones in relation to both meal frequency and macronutrient composition. DesignRandomized cross-over study with four conditions for each participant. MethodsSeven men and seven women (mean age 23±1.5years) were randomly assigned to the order of intake of a 750kcal drink with the same protein content while having either 20 energy-percent (E%) or 55 E% from carbohydrates and the remaining energy from fat. Participants were also randomized to consume the drinks as one large beverage or as five 150kcal portions every 30min, starting in the fasting state in the morning. Energy expenditure (EE) was determined every 30min by indirect calorimetry. Hormonal responses and suppression of hunger (by visual-analogue scales) were also studied. A p<0.013 was considered statistically significant following Bonferroni-correction. ResultsThe area under the curve (AUC) for EE was higher during the 2.5h after the high-carbohydrate drinks (p=0.005 by Wilcoxon) and also after ingesting one drink compared with five (p=0.004). AUC for serum active GLP-1 was higher after single drinks compared with five beverages (p=0.002). Although GLP-1 levels remained particularly high at the end of the test during the low-carbohydrate meals, the AUC did not differ compared with the high-carbohydrate occasions (low-carbohydrate: 58.9±18pg/ml/h, high-carbohydrate: 45.2±16pg/ml/h, p=0.028). Hunger sensations were suppressed more after single beverages compared with five small drinks (p=0.009). ConclusionsWe found higher EE during 2.5h following one large drink compared with five smaller beverages. Since hunger was also suppressed more efficiently, and serum GLP-1 levels were higher after one compared with five smaller drinks, our findings do not support nibbling to avoid hunger or to keep up EE from morning to noon.

Realistic Test-Meal Protocols Lead to Blunted Postprandial Lipemia but Similar Inflammatory Responses Compared with a Standard High-Fat Meal

BackgroundA substantial increase in triglycerides (TGs) after a meal is associated with an increased risk of cardiovascular disease. Most studies investigating the effects of a meal on TGs have not used meals that reflect typical consumption. ObjectiveThe objective of this study was to compare the TG and inflammatory responses of true-to-life meals, containing moderate fat and energy contents, with a high-fat, high-energy, low-carbohydrate meal (HFM) typically used to test TG responses. MethodsNine healthy, insufficiently active men [mean ± SD age: 25.1 ± 6.7 y; body mass index (in kg/m2): 25.8 ± 7.0; <150 min moderate- to vigorous-intensity physical activity/wk] completed 3 meal trials in random order: an HFM (17 kcal/kg, 60% fat), a moderate-fat meal (MFM; 8.5 kcal/kg, 30% fat), and a biphasic meal (BPM), in which participants consumed the full MFM at baseline and 3 h postmeal. Blood samples were collected via an indwelling catheter at baseline and hourly for 6 h. ResultsPeak blood TGs were significantly greater (P = 0.003) after the HFM (285.2 ± 169.7 mg/dL) than after the MFM (156.0 ± 98.7 mg/dL), but the BPM (198.3 ± 182.8 mg/dL) was not significantly different from the HFM (P = 0.06) or the MFM (P = 0.99). Total area under the curve for TGs was greater after the HFM (1348.8 ± 783.7 mg/dL × 6 h) than after the MFM (765.8 ± 486.8 mg/dL × 6 h; P = 0.0005) and the BPM (951.8 ± 787.7 mg/dL × 6 h; P = 0.03), although the MFM and BPM were not significantly different (P = 0.72). There was a significant time-by-meal interaction for interferon γ, but not for interleukins 6, 8, or 10. ConclusionThese findings in insufficiently active, healthy young men suggest that the large TG response after HFMs in previous studies may not reflect the metabolic state of many individuals in daily life.

An acute intake of theobromine does not change postprandial lipid metabolism, whereas a high-fat meal lowers chylomicron particle number

Postprandial responses predict cardiovascular disease risk. However, only a few studies have compared acute postprandial effects of a low-fat, high-carbohydrate (LF) meal with a high-fat, low-carbohydrate (HF) meal. Furthermore, theobromine has favorably affected fasting lipids, but postprandial effects are unknown. Because both fat and theobromine have been reported to increase fasting apolipoprotein A-I (apoA-I) concentrations, the main hypothesis of this randomized, double-blind crossover study was that acute consumption of an HF meal and a theobromine meal increased postprandial apoA-I concentrations, when compared with an LF meal. Theobromine was added to the LF meal. Nine healthy men completed the study. After meal intake, blood was sampled frequently for 4hours. Postprandial apoA-I concentrations were comparable after intake of the 3 meals. Apolipoprotein B48 curves, however, were significantly lower and those of triacylglycerol were significantly higher after HF as compared with LF consumption. Postprandial free fatty acid concentrations decreased less, and glucose and insulin concentrations increased less after HF meal consumption. Except for an increase in the incremental area under the curve for insulin, theobromine did not modify responses of the LF meal. These data show that acute HF and theobromine consumption does not change postprandial apoA-I concentrations. Furthermore, acute HF consumption had divergent effects on postprandial apolipoprotein B48 and triacylglycerol responses, suggesting the formation of less, but larger chylomicrons after HF intake. Finally, except for an increase in the incremental area under the curve for insulin, acute theobromine consumption did not modify the postprandial responses of the LF meal.

A randomized trial on the optimization of 18F-FDG myocardial uptake suppression: implications for vulnerable coronary plaque imaging.

(18)F-FDG PET/CT can be used to detect arterial atherosclerotic plaque inflammation. However, avid myocardial glucose uptake may preclude its use for visualizing coronary plaques. Fatty acid loading or calcium channel blockers could decrease myocardial (18)F-FDG uptake, thus assisting coronary plaque inflammation identification. The present prospective randomized trial compared the efficacies of different interventions for suppressing myocardial (18)F-FDG uptake. We also investigated whether circulating free fatty acid (cFFA) levels predicted the magnitude of myocardial (18)F-FDG uptake. Thirty-six volunteers ate a high-fat low-carbohydrate meal, followed by a 12-h fasting period. They were then randomized to 1 of 4 intervention groups. Group 1 received no additional preparation and served as a reference. Groups 2 and 3, respectively, received a commercial high-fat solution containing 43.8 g of lipids or 50 mL of olive oil 1 h before (18)F-FDG injection to evaluate the impact of fatty acid loading on myocardial (18)F-FDG uptake. Group 4 received verapamil to evaluate the effect of calcium channel blockers. Cardiac PET/CT was performed after administration of 370 MBq of (18)F-FDG. Myocardial uptake suppression was assessed using a qualitative visual scale and by measuring the myocardial maximum standardized uptake value (SUV(max)). Insulin, glucose, and cFFA were serially measured. The qualitative visual scale showed good myocardial (18)F-FDG uptake suppression in 8 of 9, 5 of 9, 4 of 9, and 8 of 9 subjects of groups 1, 2, 3, and 4, respectively (P = 0.09). SUV(max) did not significantly differ between groups (P = 0.17). Interestingly, cFFA levels were higher in volunteers with good suppression (0.80 ± 0.31 mmol/L) than in those with poor suppression (0.53 ± 0.15 mmol/L; P = 0.011). We found an inverse correlation between cFFA level (measured at (18)F-FDG injection) and the SUV(max) (R = 0.61). Receiver-operating-characteristic curve analysis identified 0.65 mmol/L cFFA as the best cutoff value to predict adequate (18)F-FDG uptake suppression (positive predictive value, 89%). A high-fat low-carbohydrate meal followed by a 12-h fasting period effectively suppressed myocardial (18)F-FDG uptake in most subjects. Neither complementary fatty acid loading nor verapamil administered 1 h before (18)F-FDG injection conferred any additional benefit. Myocardial (18)F-FDG uptake was inversely correlated with cFFA level, representing an interesting way to predict myocardial (18)F-FDG uptake suppression.

AB0961 Clinical Utility of 18F-Fdg-Pet/Ct for Evaluation of Patients with Musculoskeletal Sarcoidosis

BackgroundSarcoidosis is a systemic granulomatous disease of unknown cause mainly affecting the lung and the lymphatic system. Muscles, joints and bones may also be involved symptomatically or asymptomatically. Detection of...

Emotions and Food Consumption (Macronutrient) in a Foodservice College Setting—A Mixed Methods Study

The aim of this research is to critically evaluate the relationship between emotions and food consumption (macronutrient) in a realistic eating environment, a college cafeteria. Subjects (n = 408) completed an emotions questionnaire before and after freely choosing, paying for, and consuming a hot main meal. Eleven narrative interviews were also undertaken. The results demonstrated a greater feeling of contentment with a high-fat, high-energy meal, whereas with a low-carbohydrate meal, participants felt unfulfilled. Emotions appear to have a noticeable effect on meals and their consumption, which is not necessarily brought out in the quantitative research alone.

Effects of Different Proportion of Carbohydrate in Breakfast on Postprandial Glucose Excursion in Normal Glucose Tolerance and Impaired Glucose Regulation Subjects

The variability of postprandial plasma glucose is an independent risk factor for diabetes. The type and amount of carbohydrate may be important determinants of glycemic control. The aim of the study was to compare the effects of different proportions of carbohydrate in breakfast on postprandial blood glucose fluctuations in impaired glucose regulation (IGR) and normal glucose tolerance (NGT) subjects. This is a cross-sectional study of two groups including 55 subjects with IGR and 78 individuals with NGT. Their recorded breakfast was sorted into low-carbohydrate (LC) (carbohydrate <45%), medium-carbohydrate (MC) (carbohydrate 45-65%), and high-carbohydrate (HC) (carbohydrate >65%) meals according to the proportion of carbohydrate. Glucose concentrations were continuously measured with a continuous glucose monitoring system, and parameters such as the incremental area under the curve (iAUC) of glucose and postprandial glucose excursion (PPGE) were calculated to evaluate postprandial glucose fluctuations. The postprandial fluctuations of glucose increased gradually with increased proportions of carbohydrate in breakfast in both IGR and NGT subjects. For the MC and HC meals, iAUC, PPGE, postprandial glucose spike (PGS), and mean blood glucose were significantly greater than those in the NGT group (P<0.05), respectively. The median time to PGS and the time period in which glucose concentrations decreased to baseline after the MC and HC meals in the IGR group were significantly longer than those in the NGT group (P<0.01), respectively. Compared with the NGT subjects for the HC meal, the IGR subjects consuming the MC meal had greater PGS, range of glucose concentrations, SD, and PPGE (P<0.05). The proportion of carbohydrate in breakfast contributes to glucose excursions in the NGT and IGR subjects. In the IGR subjects, a HC meal should be avoided and a LC meal should be recommended to prevent development of diabetes.

Low carbohydrate meals or a small dose of insulin normalises one-hour blood glucose in a woman with normal glucose tolerance and elevated one-hour postload glucose: a case report

Low carbohydrate meals or a small dose of insulin normalises one-hour blood glucose in a woman with normal glucose tolerance and elevated one-hour postload glucose: a case report

Metabolic response to high-carbohydrate and low-carbohydrate meals in a nonhuman primate model

We established a model of chronic portal vein catheterization in an awake nonhuman primate to provide a comprehensive evaluation of the metabolic response to low-carbohydrate/high-fat (LCHF; 20% carbohydrate and 65% fat) and high-carbohydrate/low-fat (HCLF; 65% carbohydrate and 20% fat) meal ingestion. Each meal was given 1 wk apart to five young adult (7.8 ± 1.3 yr old) male baboons. A [U-¹³C]glucose tracer was added to the meal, and a [6,6-²H₂]glucose tracer was infused systemically to assess glucose kinetics. Plasma areas under the curve (AUCs) of glucose, insulin, and C-peptide in the femoral artery and of glucose and insulin in the portal vein were higher (P ≤ 0.05) after ingestion of the HCLF compared with the LCHF meal. Compared with the LCHF meal, the rate of appearance of ingested glucose into the portal vein and the systemic circulation was greater after the HCLF meal (P < 0.05). Endogenous glucose production decreased by ∼40% after ingestion of the HCLF meal but was not affected by the LCHF meal (P < 0.05). Portal vein blood flow increased (P < 0.001) to a similar extent after consumption of either meal. In conclusion, a LCHF diet causes minimal changes in the rate of glucose appearance in both portal and systemic circulations, does not affect the rate of endogenous glucose production, and causes minimal stimulation of C-peptide and insulin. These observations demonstrate that LCHF diets cause minimal perturbations in glucose homeostasis and pancreatic β-cell activity.

The relationship between emotions and food consumption (macronutrient) in a foodservice college setting – a preliminary study

Many aspects of eating out have been studied, yet emotions remain an under-researched area, despite having been shown to play a significant role in food consumption. The aim of this research is to critically evaluate the relationship between emotions and food consumption (macronutrient) in a realistic eating environment, a college cafeteria. Subjects (n = 408), diners using a cafeteria, completed an emotions questionnaire before and after freely choosing, paying for and consuming a hot main meal. The results demonstrated a greater feeling of contentment with a high fat, high energy meal, whereas with a low carbohydrate meal, participants felt unfulfilled. In addition, a high protein meal also leads to a feeling of contentment. These results are rather counter-intuitive to public health nutrition policy but indicate the importance of inclusion of a protein or high carbohydrate item in any dish design in a foodservice setting.

Does dietary protein and carbohydrate intake influence blastocyst development and pregnancy rates?

Busy professionals are notorious for eating low protein and high carbohydrate meals. This study seeks to determine if the nutritional components of IVF patient's daily diet impacts blastocyst development and pregnancy outcomes.

Number of foods available at a meal determines the amount consumed

The number of foods available at a meal has been suggested as a major determinant of the amount consumed. Two studies conducted in humans test this idea by altering the number of foods available at a meal where participants eat the available foods ad libitum. In Study 1, dinner intake of twenty-seven young adults was measured. The amount consumed was measured when subjects were served either: (a) a composite meal (a protein rich food, a carbohydrate rich food, and a vegetable), (b) a low carbohydrate meal (protein rich food and vegetable), or (c) a vegetarian meal (carbohydrate rich food and vegetable). In Study 2, twenty-four subjects were given two different meals presented either as individual foods or as a composite meal (stir-fry or stew). Both studies show that the greater the number of foods offered at a meal, the greater the total intake. Study 2 demonstrated that the effects observed in Study 1 could not be attributed to different nutrient compositions, but was rather due to the presentation of the individual foods because the same foods that were offered as individual foods were combined to make the composite meal. The results demonstrate that the greater the number of foods offered at a meal, the greater the spontaneous intake of those foods. This finding is important because not only does it expand the concept of variety from the kinds of foods to the number of foods, but it presents an environmental variable that might contribute to overeating and obesity.

Differential effects of low-carbohydrate and low-fat diets on inflammation and endothelial function in diabetes

Objective To characterize acute (postprandial) and chronic (after a 6-month period of weight loss) effects of a low-carbohydrate vs. a low-fat diet on subclinical markers of cardiovascular disease (CVD) in adults with type 2 diabetes. Design At baseline and 6 months, measures of C-reactive protein (CRP), interleukin-6 (IL-6), soluble intercellular adhesion molecule (sICAM) and soluble E-selectin were obtained from archived samples ( n=51) of participants randomized in a clinical trial comparing a low-carbohydrate and a low-fat diet. In a subset of participants ( n=27), postprandial measures of these markers were obtained 3 h after a low-carbohydrate or low-fat liquid meal. Endothelial function was also measured by reactive hyperemic peripheral arterial tonometry during the meal test. Paired t tests and unpaired t tests compared within- and between-group changes. Results There were no significant differences observed in postprandial measures of inflammation or endothelial function. After 6 months, CRP (mean±S.E.) decreased in the low-fat arm from 4.0±0.77 to 3.0±0.77 ( P=.01). In the low-carbohydrate arm, sICAM decreased from 234±22 to 199±23 ( P=.001), and soluble E-selectin decreased from 93±10 to 82±10 ( P=.05.) A significant correlation between change in high-density lipoprotein and change in soluble E-selectin ( r=−0.33, P=.04) and with the change in ICAM ( r=−0.43, P=.01) was observed. Conclusions Low-carbohydrate and low-fat diets both have beneficial effects on CVD markers. There may be different mechanisms through which weight loss with these diets potentially reduces CVD risk.

Metabolic Responses To A Single Low-carbohydrate And Low-fat Meal At Rest And During Exercise In Adult Females

PURPOSE: The present study examined the metabolic response to a single low-carbohydrate (LC) and low-fat (LF) meal at rest and during exercise in females. METHODS: All data are reported as the mean + standard deviation. Subjects included 8 premenopausal females who engaged in aerobic activity for > 3 days/week for at least 6 months (age 33.0 + 6.3 years, BMI 26.8 + 3.5 kg/m2, body fat 30.9 + 6.1%, and peak oxygen consumption (VO2peak) 41.8 + 5.7 ml/kg/min). Subjects completed a LC and LF testing session administered in random order and after a 12 hr fast. Respiratory gas exchange (RER) measurements were taken for 20 min fasted before the test meal was consumed, for 55 min postprandial (PP), and during 30 min of treadmill exercise performed at 60 to 65% of VO2peak. Blood was collected for assessment of glucose (G), insulin (IN), triglycerides (TG), and free fatty acids (FFA) during the final 10 min of the fasting and PP time periods and immediately post-exercise (PE). G, FFA, and TG were analyzed using enzymatic assays. IN was analyzed using the ELISA technique. The LF meal provided 396 kcal (78% carbohydrate, 7% fat, and 15% protein). The LC meal provided 392 kcal (15% carbohydrate, 68% fat, and 18% protein). Repeated Measures Factorial ANOVAs were computed for LC and LF over time. RESULTS: No significant differences (p > 0.05) existed between test meals for fasting values of RER, G, IN, TG, or FFA. PP IN (µU/ml) levels were significantly lower (p < 0.05) following LC compared to LF (10.7 + 6.1 vs. 26.0 + 21.0). PE FFA (mEq/L) levels were significantly greater (p < 0.05) following LC (1.1 + 0.3 vs. 0.5 + 0.3). PE TG (mg/dL) levels were significantly greater (p < 0.05) following LC (152.0 + 53.1 vs. 114.4 + 40.9). RER was significantly lower (p < 0.05) from 0 to 25 min PP and from 25 to 55 min PP after LC (0.72 + 0.04 vs. 0.80 + 0.04 and 0.75 + 0.03 vs. 0.86 + 0.04). RER during exercise was significantly lower (p < 0.05) after LC (0.81 + 0.04 vs. 0.86 + 0.04). CONCLUSIONS: In moderately active adult females, ingestion of a single LC meal resulted in greater lipid oxidation at rest and during exercise as compared to a single LF meal. Although macronutrient distribution appears to have dictated substrate utilization in the present study, more research is needed regarding the long-term effects of macronutrient redistribution with and without exercise on substrate utilization.

Postprandial ghrelin and PYY responses of male subjects on low carbohydrate meals to varied balancing proportions of proteins and fats

This study was conducted to investigate whether a higher proportion of protein or fat is more favorable for optimal ghrelin and peptide YY (PYY) release in subjects consuming low carbohydrate meals. Eight normal weight men received, on three separate occasions, high protein low fat (HPLF) (40% protein, 25% fat), low protein high fat (LPHF) (10% protein, 55% fat) or medium protein medium fat (MPMF) (25% protein, 40% fat) meals, with equal low carbohydrates content in all three meals (35% of energy). Postprandial blood samples were collected before and 15, 30, 60, 120, 180 and 240min following the ingestion of each meal. Plasma acylated ghrelin and PYY(3-36) as well as serum insulin, glucose and triglycerides were measured. Comparing meals and considering each time point separately, a trend for a statistically significant difference in acylated ghrelin was observed between HPLF and LPHF meals and a statistically significant change of PYY from baseline was noted between HPLF and LPHF meals as compared to the MPMF meal at certain time points. When data were pooled together, a statistically significant difference in acylated ghrelin change from baseline was observed between HPLF and LPHF meals, while both HPLF and LPHF meals resulted in a significantly higher PYY(3-36) release in comparison to MPMF meal. AUC data analysis for PYY(3-36) revealed significantly higher values following HPLF in comparison to MPMF meal. Correlation analysis revealed a significant negative correlation between acylated ghrelin and insulin only with the HPLF meal. Postprandial glucose and triglyceride levels were not significantly different between the three meals. In subjects consuming low carbohydrate meals, higher concentrations of proteins to fat seem to have more favorable effects on postprandial appetite hormones.

Carbohydrate ingestion and soccer skill performance during prolonged intermittent exercise

The aim of this study was to investigate the effect of ingesting a carbohydrate-electrolyte solution, during the 90-min Loughborough Intermittent Shuttle Test, on soccer skill performance. Seventeen male soccer players ingested either a 6.4% carbohydrate-electrolyte solution or placebo solution equivalent to 8 ml · kg−1 body mass before exercise and 3 ml · kg−1 body mass after every 15 min of exercise, in a double-blind randomized cross-over design, with the trials separated by 7 days. The evening before the main trial, the participants performed glycogen-reducing exercise on a cycle ergometer (80 min at 70%[Vdot]O2max) and were then fed a low-carbohydrate meal. After a 12-h overnight fast, they performed The Loughborough Soccer Passing Test before and after every 15 min of exercise. Analysis of the combined skill test data showed a significant time effect (P = 0.001) with differences between 0–45 and 75–90 min (P < 0.05). There was a 3% reduction in skill performance from before to after exercise in the carbohydrate-electrolyte trial, whereas in the placebo trial the decrease was 14% (P = 0.07). In conclusion, skill performance during the simulated soccer activity appeared to deteriorate in the last 15–30 min of exercise. However, providing 52 g · h−1 carbohydrate during exercise showed a tendency to better maintain soccer skill performance than a taste-matched placebo.