Liquid meal composition, postprandial satiety hormones, and perceived appetite and satiety in obese women during acute caloric restriction

OBJECTIVE: The purpose of this study was to compare postprandial satiety regulating hormone responses (pancreatic polypeptide (PP) and peptide tyrosine tyrosine (PYY)) and visual analog scale- (VAS) assessed perceived appetite and satiety between liquid high-protein (HP) and high-carbohydrate (HC) meals in obese women during acute (24-h) caloric restriction. DESIGN: Eleven obese premenopausal women completed two conditions in random order in which they consumed 1500 calories as six 250-calorie HP meals or six 250-calorie HC meals over a 12-h period. Blood samples were taken at baseline and every 20 min thereafter and analyzed for PP and PYY concentrations. At these same points, perceived hunger and fullness were assessed with a VAS. The incremental area under the curve (iAUC) was used to compare postprandial responses. RESULTS: THE 12-H PP AND PYY IAUC WERE GREATER (P0.05) DURING THE HP CONDITION (PP: 4727±1306 pg/ml×12 h, PYY: 1373±357 pg/ml×12 h) compared with the HC condition (PP: 2300±528 pg/ml×12 h, PYY: 754±246 pg/ml×12 h). Perceived hunger and fullness were not different between conditions (P>0.05). The greatest changes in PYY and perceived fullness occurred after the morning meals during both conditions. CONCLUSIONS: These data suggest that in obese women during acute caloric restriction before weight loss, i) liquid HP meals, compared with HC meals, result in greater postprandial PP and PYY concentrations, an effect not associated with differential appetite or satiety responses, and ii) meal-induced changes in PYY and satiety are greatest during the morning period, regardless of dietary macronutrient composition

Alteration of postprandial glucose and insulin concentrations with meal frequency and composition

A frequent eating pattern may alter glycaemic control and augment postprandial insulin concentrations in some individuals due to the truncation of the previous postprandial period by a subsequent meal. The present study examined glucose, insulin, C-peptide and glucose-dependent insulinotropic peptide (GIP) responses in obese individuals when meals were ingested in a high-frequency pattern (every 2 h, 6M) or in a low-frequency pattern (every 4 h, 3M) over 12 h. It also examined these postprandial responses to high-frequency, high-protein meals (6MHP). In total, thirteen obese subjects completed three 12 h study days during which they consumed 6276 kJ (1500 kcal): (1) 3M – 15 % protein and 65 % carbohydrate; (2) 6M – 15 % protein and 65 % carbohydrate; (3) 6MHP – 45 % protein and 35 % carbohydrate. Blood samples were collected every 10 min and analysed for glucose, insulin, C-peptide and GIP. Insulin total AUC (tAUC) and peak insulin concentrations (P< 0·05) were higher in the 3M condition than in the 6M condition, but there were no differences in glucose tAUC between the conditions. The 6MHP regimen (glucose: 3569 (se 83) mmol/l × min (64·3 (se 1·5) g/dl × min), insulin: 1·577 (se 0·146) pmol/l (22·7 (se 2·1) μIU/dl) for 12 h) lowered glucose and insulin excursions more so over 12 h than either the 3M regimen (glucose: 3913 (se 78) mmol/l × min (70·5 (se 1·4) g/dl × min), insulin: 2·195 (se 0·146) pmol/l × min (31·6 (se 2·1) μIU/dl × min) for 12 h) or the 6M regimen (glucose: 3902 (se 83) mmol/l × min (70·3 (se 1·5) g/dl × min), insulin: 1·861 (se 0·174) pmol/l × min (26·8 (se 2·5) μIU/dl × min) for 12 h; P< 0·01). Insulin secretion, GIP concentrations and the glucose:insulin ratio were not altered by meal frequency or composition. In obese subjects, ingestion of meals in a low-frequency pattern does not alter glucose tAUC, but increases postprandial insulin responses. The substitution of carbohydrates with protein in a frequent meal pattern results in tighter glycaemic control and reduced postprandial insulin responses

Yoga training improves quality of life in women with asthma

Objectives: Individuals with asthma frequently suffer with a decrease in quality of life. Yoga has been shown to improve autonomic function in the healthy population and has been used as an alternative therapy to help improve symptoms associated with various diseases. Purpose: The purpose of this study was to assess whether 10 weeks of yoga training can improve quality of life and heart rate variability (HRV) in patients with asthma. Design: Nineteen (19) females were randomly assigned to a yoga group or a control group for a 10-week intervention while still following guidelines established by their physician. All subjects answered the St. George's Respiratory Questionnaire (SGRQ) to assess quality of life and performed an isometric handgrip exercise test to assess HRV. Results: Based on the SGRQ, significant improvements (45%, p<0.05) in quality of life were observed with the yoga training, while no changes were found in the control group. Resting hemodynamic measures improved significantly in the yoga group compared to the control group (p<0.05). The yoga group decreased parasympathetic modulation (HFnu [normalized units]) pre-to postintervention (0.45±0.60 to 0.35±0.06 nu, p<0.05, respectively) in response to the isometric forearm exercise (IFE), whereas the control group did not change. Additionally, the yoga group increased sympathetic (LFnu) (pre 0.47±0.07 to post 0.60±0.07 nu, p<0.05) and sympathovagal modulation (logLF/HF) (pre 4.61±0.39 to post 5.31±0.44, p<0.05, respectively) during IFE with no change in the control group. Conclusions: Yoga training improved quality of life in women with mild-to-moderate asthma and resulted in decreased parasympathetic and increased sympathetic modulation in response to an IFE

Effect of diurnal exercise timing on postprandial glucose responses: A randomized controlled trial

PURPOSE: Postprandial exercise has been shown to reduce postprandial glucose (PPG) response to a greater degree than preprandial exercise, suggesting an important yet under-acknowledged role for exercise timing on glycemic control. Whether diurnal timing of exercise imparts additional benefits on PPG responses remains unclear. This study aimed to determine the diurnal effect of exercise timing on PPG response in individuals enrolled into a 12-week supervised multi-modal exercise training program. METHODS: Forty sedentary overweight individuals (17 males, 23 female; age: 51 ± 13 years; BMI: 30.9 ± 4.2 kg/m2) with (n = 20) or without T2DM diagnosis were randomly allocated to either a morning (amEX) or evening (pmEX) exercise training group. All participants completed the 12-week supervised multi-modal exercise training program (3 days per week), which consisted of 30 minutes of aerobic exercise (walking protocol) and 4 resistance-based exercises (3 sets of 12-18 repetitions). The amEX and pmEX training sessions occurred in the postprandial state between 0700-0900h and 1700-1900h, respectively. Changes in postprandial glucose (PPG) and insulin (PPI) responses, during a mixed meal tolerance test (MMTT) were the primary outcome measures of the study assessed at baseline and post-intervention at 12 weeks. All data is displayed as mean differences ± SD. RESULTS: Exercise training reduced (main effect of time, p < 0.01) PPG and PPI concentrations during the MMTT, with no group differences observed (p = 0.69). A significantly greater reduction in PPG-iAUC was observed for the pmEX group (-78.56 mmol/L) when compared to the amEX group (-33.22 mmol/L) at post-intervention (p = 0.03). Reductions in PPI iAUC (main effect of time, p < 0.01) were observed at post-intervention, with no group differences reported (p = 0.18) CONCLUSIONS: Irrespective of the diurnal timing of exercise performance, 12-weeks of multi-modal exercise training significant improved PPG and PPI responses in both overweight non-T2DM and T2DM individuals

Effect of meal frequency on glucose and insulin excursions over the course of a day

Background & aims: This study characterized the glucose and insulin responses to temporal alterations in meal frequency, and alterations in the macronutrient composition. Methods: Eight subjects underwent three separate 12-h meal tests: three high carbohydrate (3CHO) meals, 6 high carbohydrate meals (6CHO), 6 high-protein meals (6HP). Blood samples were taken at 15-min intervals. Integrated area under the curve (AUC) concentrations for glucose and plasma insulin were determined (total, 4-h, and 2-h blocks) for each meal condition. Results: Baseline glucose and insulin values were not different between study days. Peak glucose levels were highest on the 3CHO day; however the 12 h glucose AUC was higher during the 6CHO condition (p = 0.029) than 3CHO condition, with no difference in the insulin response. The 6HP condition resulted in a decreased glucose AUC (p = 0.004) and insulin AUC (p = 0.012) compared to 6CHO. Conclusions: In non-obese individuals, glucose levels remained elevated throughout the day with frequent CHO meals compared to 3CHO meals, without any differences in the insulin levels. Increasing the protein content of frequent meals attenuated both the glucose and insulin response. These findings of elevated glucose levels throughout the day warrant further research, particularly in overweight and obese individuals with and without type 2 diabete

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Effect of increased physical activity on fructose-induced glycemic response in healthy individuals

Background/Objectives: The purpose of the current study was to determine whether increased physical activity (PA) altered glycemic control while ingesting an energy-balanced high-fructose diet. Subjects/Methods: Twenty-two normal-weight men and women (age: 21.2±0.6 years; body mass index: 22.6 ±0.6 kg/m2) participated in a randomized, cross-over design study in which they ingested an additional 75 g of fructose for 14 days while either maintaining low PA (FR+inactive) (12 000 steps/day). Before and following the 2-week loading period, a fructose-rich meal challenge was administered and blood was sampled at baseline and for 6 h after the meal and analyzed for glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), c-peptide, glucose and insulin concentrations. Results: Plasma insulin, glucose, c-peptide, GIP and GLP-1 concentrations significantly increased in response to the test meal on all test visits (P<0.05). C-peptide incremental area under the curve (AUC) decreased by 10 208 ±120 pmol/l × min for 6 h from pre to post Fr+active intervention (P=0.02) leading to a decrease in plasma insulin total AUC (pre: 58 470.2±6261.0 pmol/l; post: 49 444.3±3883.0 pmol/l; P=0.04) resulting in a decrease Δpeak[Insulin] (P=0.009). Following the FR+active intervention, GIP total AUC significantly decreased (P=0.005) yet only males had a lower total GLP-1 AUC after both interventions (P=0.049). There were no sex differences in GIP levels. Conclusions: Increased PA attenuates the deleterious effects on glycemic control caused by a high-fructose diet. These changes in glycemic control with PA are associated with decreases in insulin and GIP concentrations

The effect of exercise timing on Glycemic Control

Despite the acknowledgment of exercise as a cornerstone in the management of type 2 diabetes (T2D), the importance of exercise timing has only recently been considered