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Combining Short-Term Interval Training with Caloric Restriction Improves ß-Cell Function in Obese Adults.
Francois, ME, Gilbertson, NM, Eichner, NZM, Heiston, EM, Fabris, C, Breton, M, Mehaffey, JH, Hassinger, T, Hallowell, PT, Malin, SK
Nutrients. 2018;10(6)
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The development of type 2 diabetes is characterised by insulin resistance and dysfunction of the pancreas. Over time, loss of function of the ß-cells of the pancreas leads to impaired tolerance of blood sugar and type 2 diabetes. Low-calorie diets have been shown to improve blood sugar regulation, but it is unclear what impact interval exercise has in addition to a low-calorie diet. This study tested the hypothesis that combining interval exercise with a low-calorie diet would enhance pancreatic function compared to a low calorie diet alone in adults with obesity. Twenty-six obese adults were assigned to 2 weeks of a LCD (1200 kcal/day), using meal replacement shakes for breakfast and lunch. Half the group also underwent 60 minutes of interval training a day; after each session they received a 350 kcal shake to compensate for the calories burned during training. A series of blood tests was carried out to measure glucose tolerance and insulin secretion rates. Combining a low calorie diet with interval training reduced glucose and insulin secretion rates, whereas the low calorie diet alone did not. Both interventions improved insulin sensitivity. The authors concluded that the data supports combining low calorie diets with interval training to preserve pancreatic function and prevent type 2 diabetes.
Abstract
Although low-calorie diets (LCD) improve glucose regulation, it is unclear if interval exercise (INT) is additive. We examined the impact of an LCD versus LCD + INT training on ß-cell function in relation to glucose tolerance in obese adults. Twenty-six adults (Age: 46 ± 12 year; BMI 38 ± 6 kg/m²) were randomized to 2-week of LCD (~1200 kcal/day) or energy-matched LCD + INT (60 min/day alternating 3 min at 90 and 50% HRpeak). A 2 h 75 g oral glucose tolerance test (OGTT) was performed. Insulin secretion rates (ISR) were determined by deconvolution modeling to assess glucose-stimulated insulin secretion ([GSIS: ISR/glucose total area under the curve (tAUC)]) and ß-cell function (Disposition Index [DI: GSIS/IR]) relative to skeletal muscle (Matsuda Index), hepatic (HOMA-IR) and adipose (Adipose-IRfasting) insulin resistance (IR). LCD + INT, but not LCD alone, reduced glucose and total-phase ISR tAUC (Interactions: p = 0.04 and p = 0.05, respectively). Both interventions improved skeletal muscle IR by 16% (p = 0.04) and skeletal muscle and hepatic DI (Time: p < 0.05). Improved skeletal muscle DI was associated with lower glucose tAUC (r = -0.57, p < 0.01). Thus, LCD + INT improved glucose tolerance more than LCD in obese adults, and these findings relate to ß-cell function. These data support LCD + INT for preserving pancreatic function for type 2 diabetes prevention.
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Effects of 3-week total meal replacement vs. typical food-based diet on human brain functional magnetic resonance imaging food-cue reactivity and functional connectivity in people with obesity.
Kahathuduwa, CN, Davis, T, O'Boyle, M, Boyd, LA, Chin, SH, Paniukov, D, Binks, M
Appetite. 2018;120:431-441
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Weight loss diets that use total meal replacement shakes have been shown to reduce food cravings compared to typical reduced-calorie diets. The mechanism for this is unclear. This study examined the effects of a 3-week 1120 kcal per day meal replacement diet compared to a reduced calorie diet on activity in areas of the brain associated with food cravings. Thirty-two obese adults participated in the study. Before and after the study, the participants were given magnetic resonance imaging (MRI) scans to measure activity in different areas of the brain. They were also questioned on food cravings and weighed. The group following the meal replacement diet experienced a significant weight loss of 4.87 kg, a reduction in body fat of 2.19 kg and reduced their overall food cravings. The reduced calorie diet group also experienced significant weight loss and a reduction in body fat (2.37kg and 1.64kg, respectively) but less than the meal replacement group. The meal replacement group experienced reduced cravings compared to the reduced calorie diet group. MRI scans suggested that this was due to changes in activity in the food reward related regions in several areas of the brain, resulting in an increase in executive control. The authors concluded that meal replacement diets may increase executive control within the brain, leading to a reduction in food cravings and weight loss.
Abstract
OBJECTIVES Calorie restriction via total meal replacement (TMR) results in greater reduction of food cravings compared to reduced-calorie typical diet (TD). Direct evidence of the impact of these interventions on human brain fMRI food-cue reactivity (fMRI-FCR) and functional connectivity is absent. We examined the effects of a 3-week 1120 kcal/d TMR intervention as compared to an iso-caloric TD intervention using an fMRI-FCR paradigm. METHODS Thirty-two male and female subjects with obesity (19-60 years; 30-39.9 kg/m2) participated in a randomized two-group repeated measures dietary intervention study consisting of 1120 kcal/d from either 1) TMR (shakes), 2) TD (portion control). Pre-intervention and following the 3-week diet fMRI-FCR, functional connectivity, food cravings (Food Craving Inventory) and weight were considered. RESULTS Compared to TD, TMR showed increased fMRI-FCR of the bilateral dorsolateral prefrontal (dlPFC), orbitofrontal, anterior cingulate, primary motor and left insular cortices and bilateral nucleus accumbens regions in the post-intervention state relative to the pre-intervention state. Compared to TD, TMR was also associated with negative modulation of fMRI-FCR of the nucleus accumbens, orbitofrontal cortex and amygdala by dlPFC. Reduced body weight (4.87 kg, P < 0.001), body fat (2.19 kg, P = 0.004) and overall food cravings (0.41, P = 0.047) were seen in the TMR group. In the TD group reduced body weight (2.37 kg, P = 0.004) and body fat (1.64 kg, P = 0.002) were noted. Weight loss was significantly greater in TMR versus TD (2.50 kg, P = 0.007). CONCLUSIONS Greater weight loss and reduced cravings, coupled with stronger activations and potential negative modulation of the food reward related regions by the dlPFC during exposure to visual food cues is consistent with increased executive control in TMR vs. TD.
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Changes in Gut Microbiota-Related Metabolites and Long-term Successful Weight Loss in Response to Weight-Loss Diets: The POUNDS Lost Trial.
Heianza, Y, Sun, D, Smith, SR, Bray, GA, Sacks, FM, Qi, L
Diabetes care. 2018;41(3):413-419
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Evidence has demonstrated that weight loss contributes to lowering the risk of developing type 2 diabetes among obese patients. The aim of this study was to examine whether diet-induced metabolites were associated with improvements in adiposity and metabolism during a weight-loss diet intervention in 510 overweight and obese individuals. Participants were randomly assigned to one of four diets with varying macronutrient composition to adhere to for six months. Blood samples and anthropometric data were taken at baseline and 6 months to monitor changes. This study found that overweight and obese individuals with reduced choline or L-carnitine levels achieved greater improvements of adiposity and energy metabolism. Based on these results, the authors conclude that metabolites are predictive of patient responsiveness to dietary interventions, and suggest further studies evaluate these effects in the pre-diabetic obese population.
Abstract
OBJECTIVE Adiposity and the gut microbiota are both related to the risk of type 2 diabetes. We aimed to comprehensively examine how changes induced by a weight-loss diet intervention in gut microbiota-related metabolites, such as trimethylamine N-oxide (TMAO) and its precursors (choline and l-carnitine), were associated with improvements in adiposity and regional fat deposition. RESEARCH DESIGN AND METHODS This study included 510 overweight and obese individuals who were randomly assigned one of four diets varying in macronutrient intake. We examined associations of 6-month changes in blood metabolites (TMAO, choline, and l-carnitine) with improvements in body weight (BW), waist circumference (WC), body fat composition, fat distribution, and resting energy expenditure (REE). RESULTS Individuals with a greater reduction of choline (P < 0.0001) and l-carnitine (P < 0.01) rather than TMAO showed significant losses of BW and WC at 6 months. The reduction of choline was significantly predictive of decreases in body fat composition, fat distribution, and REE. Results of sensitivity analysis showed that the baseline diabetes risk status, such as the presence of hyperglycemia (31% of the total participants) and fasting glucose levels, did not modify the associations. Early changes in choline and l-carnitine were significantly predictive of weight loss over 2 years (P < 0.05 for all). Individuals with increases in choline or l-carnitine were 2.35-times (95% CI 1.38, 4.00) or 1.77-times (1.06, 2.95) more likely to fail to lose weight (-5% or more loss) at 2 years. CONCLUSIONS Overweight and obese individuals who showed decreases in circulating choline or l-carnitine levels achieved greater improvements of adiposity and energy metabolism by eating a low-calorie weight-loss diet, suggesting that such metabolites are predictive of individuals' response to the treatment. Further investigations are necessary to confirm our findings, particularly in a population with prediabetes that is more representative of the U.S. population with obesity.
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The Effect of Low-Carbohydrate Diet on Glycemic Control in Patients with Type 2 Diabetes Mellitus.
Wang, LL, Wang, Q, Hong, Y, Ojo, O, Jiang, Q, Hou, YY, Huang, YH, Wang, XH
Nutrients. 2018;10(6)
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Dietary intervention is a strategy to manage diabetes mellitus, as it can reduce the burden on islet cells and thus improve blood glucose levels, lipid profiles, and cognitive status. The aim of the study was to find out the effectiveness of the ‘six-point formula’ and the effects of a low-fat diet and low-carbohydrate diet on hyperglycaemia. The study is a prospective, single-blind randomized controlled trial which recruited 56 participants with type 2 diabetes mellitus. The participants were randomly allocated to receive either a low-fat diet or a low-carbohydrate diet. Results show that HbA1c levels (the average blood glucose levels in the last 2 – 3 months) in low-carbohydrate diet decreased significantly compared to the low-fat diet. The body mass index and the total cholesterol levels of the participants following the low-carbohydrate diet also decreased. Authors conclude that a low-carbohydrate diet can improve blood glucose, regulate blood lipids, reduce body mass index and decrease insulin doses more than a low-fat diet in Chinese patients with type 2 diabetes mellitus.
Abstract
OBJECTIVE In China, a low-fat diet (LFD) is mainly recommended to help improve blood glucose levels in patients with type 2 diabetes mellitus (T2DM). However, a low-carbohydrate diet (LCD) has been shown to be effective in improving blood glucose levels in America and England. A few studies, primarily randomized controlled trials, have been reported in China as well. METHOD Firstly, we designed two 'six-point formula' methods, which met the requirements of LCD and LFD, respectively. Fifty-six T2DM patients were recruited and randomly allocated to the LCD group (n = 28) and the LFD group (n = 28). The LCD group received education about LCD's six-point formula, while the LFD group received education about LFD's six-point formula. The follow-up time was three months. The indicators for glycemic control and other metabolic parameters were collected and compared between the two groups. RESULTS Forty-nine patients completed the study. The proportions of calories from three macronutrients the patients consumed met the requirements of LCD and LFD. Compared to the LFD group, there was a greater decrease in HbA1c level in the LCD group (-0.63% vs. -0.31%, p < 0.05). The dosages of insulin and fasting blood glucoses (FBG) in the third month were lower than those at baseline in both groups. Compared with baseline values, body mass index (BMI) and total cholesterol (TC) in the LCD group were significantly reduced in the third month (p < 0.05); however, there were no statistically significant differences in the LFD group. CONCLUSIONS LCD can improve blood glucose more than LFD in Chinese patients with T2DM. It can also regulate blood lipid, reduce BMI, and decrease insulin dose in patients with T2DM. In addition, the six-point formula is feasible, easily operable, and a practical educational diet for Chinese patients with T2DM.
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Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial.
Vargas, S, Romance, R, Petro, JL, Bonilla, DA, Galancho, I, Espinar, S, Kreider, RB, Benítez-Porres, J
Journal of the International Society of Sports Nutrition. 2018;15(1):31
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This randomised controlled trial investigated the effects of a ketogenic diet on body composition in bodybuilders. 24 healthy body-builders were randomised to either a ketogenic diet (KD), non-ketogenic diet (NKD) or to control group (CG). During the trial period, both the KD and the NKD group received a surplus of calories and the same amount of protein, 2g/kg body weight per day to promote anabolic activity. Macronutrient ratios were carbohydrate 55%, protein 20% and fat 25% in the NKD group versus <10% carbohydrate, 20% protein and 70% fat in the KD group. Participants could eat when and how often they wanted to and both groups carried out the same training programme. After eight weeks the KD group showed significantly lower total fat mass and visceral (abdominal) fat, but no gain in either total body weight or lean mass. The NKD group, on the other hand, gained lean mass and body weight, but saw no changes in total or visceral fat mass. No significant changes in body composition were observed in the CG.
Abstract
BACKGROUND Ketogenic diets (KD) have become a popular method of promoting weight loss. More recently, some have recommended that athletes adhere to ketogenic diets in order to optimize changes in body composition during training. This study evaluated the efficacy of an 8-week ketogenic diet (KD) during energy surplus and resistance training (RT) protocol on body composition in trained men. METHODS Twenty-four healthy men (age 30 ± 4.7 years; weight 76.7 ± 8.2 kg; height 174.3 ± 19.7 cm) performed an 8-week RT program. Participants were randomly assigned to a KD group (n = 9), non-KD group (n = 10, NKD), and control group (n = 5, CG) in hyperenergetic condition. Body composition changes were measured by dual energy X-ray absorptiometry (DXA). Compliance with the ketosis state was monitored by measuring urinary ketones weekly. Data were analyzed using a univariate, multivariate and repeated measures general linear model (GLM) statistics. RESULTS There was a significant reduction in fat mass (mean change, 95% CI; p-value; Cohen's d effect size [ES]; - 0.8 [- 1.6, - 0.1] kg; p < 0.05; ES = - 0.46) and visceral adipose tissue (- 96.5 [- 159.0, - 34.0] g; p < 0.05; ES = - 0.84), while no significant changes were observed in the NKD and CG in fat mass (- 0,5 [- 1.2, 0.3] kg; p > 0.05; ES = - 0.17 and - 0,5 [- 2.4, 1.3] kg; p > 0.05; ES = - 0.12, respectively) or visceral adipose tissue (- 33.8 [- 90.4, 22.8]; p > 0.5; ES = - 0.17 and 1.7 [- 133.3, 136.7]; p > 0.05; ES = 0.01, respectively). No significant increases were observed in total body weight (- 0.9 [- 2.3, 0.6]; p > 0.05; ES = [- 0.18]) and muscle mass (- 0.1 [- 1.1,1.0]; p > 0,05; ES = - 0.04) in the KD group, but the NKD group showed increases in these parameters (0.9 [0.3, 1.5] kg; p < 0.05; ES = 0.18 and (1.3[0.5, 2.2] kg; p < 0,05; ES = 0.31, respectively). There were no changes neither in total body weight nor lean body mass (0.3 [- 1.2, 1.9]; p > 0.05; ES = 0.05 and 0.8 [- 0.4, 2.1]; p > 0.05; ES = 0.26, respectively) in the CG. CONCLUSION Our results suggest that a KD might be an alternative dietary approach to decrease fat mass and visceral adipose tissue without decreasing lean body mass; however, it might not be useful to increase muscle mass during positive energy balance in men undergoing RT for 8 weeks.
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Effects of Low Versus Moderate Glycemic Index Diets on Aerobic Capacity in Endurance Runners: Three-Week Randomized Controlled Crossover Trial.
Durkalec-Michalski, K, Zawieja, EE, Zawieja, BE, Jurkowska, D, Buchowski, MS, Jeszka, J
Nutrients. 2018;10(3)
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During athletic performance, adequate amounts of carbohydrates are required to prolong the onset of fatigue. Research on whether the glycaemic index (GI) of ingested carbohydrates effects performance has been explored but has produced equivocal results. The aim of this randomised crossover study was to assess the effect of low- and moderate- GI diets on the aerobic capacity and endurance performance in 21 runners. Participants consumed a low- and moderate- GI, high carbohydrate and nutrient balanced diets for three weeks each with a two-week washout period. Aerobic capacity and body composition were measured at the beginning and end of each diet period through various athletic performance tests. This study found that after a low-GI, high-carbohydrate diet, improvements were seen in time to exhaustion and running performance. Gas exchange was improved by both diets. The low-GI carbohydrate diet helped athletes to maintain a more stable blood glucose concentration during exertion tests. Based on these results the authors suggest considering GI when planning a diet for performance athletes, and also urge further research be completed to better understand the effects of long-term GI diets with regards to exercise performance.
Abstract
The glycemic index (GI) of ingested carbohydrates may influence substrate oxidation during exercise and athletic performance. Therefore, the aim of this study was to assess the effect of low- and moderate-GI three-week diets on aerobic capacity and endurance performance in runners. We conducted a randomized crossover feeding study of matched diets differing only in GI (low vs. moderate) in 21 endurance-trained runners. Each participant consumed both, low- (LGI) and moderate-GI (MGI) high-carbohydrate (~60%) and nutrient-balanced diets for three weeks each. At the beginning and end of each diet, participants had their aerobic capacity and body composition measured and performed a 12-min running test. After LGI, time to exhaustion during incremental cycling test (ICT) and distance covered in the 12-min run were significantly increased. The MGI diet led to an increase in maximal oxygen uptake ( V ˙ O₂max), but no performance benefits were found after the MGI diet. The LGI and MGI diets improved time and workload at gas exchange threshold (GET) during ICT. The results indicate that a three-week high-carbohydrate LGI diet resulted in a small but significant improvement in athletic performance in endurance runners. Observed increase in V ˙ O₂max on MGI diet did not affect performance.
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Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial.
Gardner, CD, Trepanowski, JF, Del Gobbo, LC, Hauser, ME, Rigdon, J, Ioannidis, JPA, Desai, M, King, AC
JAMA. 2018;319(7):667-679
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Obesity is a major public health challenge and different dietary strategies are employed to lose weight. This randomised clinical trial of 609 obese adults between the age of 18 and 50 aimed to determine the effects of a healthy low-fat diet in comparison to a healthy low-carbohydrate diet on weight change over a 12 month period. The study also assessed whether 3 genetic markers and blood sugar management affected weight loss in the 2 groups. Participants in the study were offered 22 group sessions of health coaching to support adherence to the programme. 481 participants completed the study. The low-carbohydrate group lost on average 6kg and the low-fat group lost on average 5.4kg. The difference between the 2 groups did not achieve significance for weight loss. There was also no significant genetic or blood sugar management effect in relation to dietary pattern and weight loss. The authors of this study conclude that the results of this study do not help in identifying which dietary type is better for whom in relation to 3 genetic markers and blood sugar management.
Abstract
Importance: Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets. Objective: To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss. Design, Setting, and Participants: The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss. Interventions: Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality. Main Outcomes and Measures: Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss. Results: Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was -5.3 kg for the HLF diet vs -6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, -0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups. Conclusions and Relevance: In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom. Trial Registration: clinicaltrials.gov Identifier: NCT01826591.
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Early and long period follow-up results of low glycemic index diet for migraine prophylaxis.
Evcili, G, Utku, U, Öğün, MN, Özdemir, G
Agri : Agri (Algoloji) Dernegi'nin Yayin organidir = The journal of the Turkish Society of Algology. 2018;30(1):8-11
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Environmental factors such as diet and lifestyle are known to play a role in migraine. Particular foods can act as direct triggers for individuals. Also, how the individual’s diet affects their blood sugar levels may be key to the frequency and severity of their attacks. Foods that are said to have low glycaemic index (GI), i.e. they are thought to raise blood sugar levels more slowly, may help with the management of migraine. In this randomised control trial, migraine patients were randomly allocated to either a low GI diet group or a medication group. Both groups were given tips for lifestyle changes and the diet group was also advised to eat a low GI diet and avoid high GI foods, while the medication group participants kept using their preventive medication. The frequency and severity of migraine attacks was assessed before the start of the study and at 1 month and 3 months after starting the low GI diet. At 3 months, the frequency and severity of attacks reduced significantly in both groups and the low GI diet was noted to be as effective as the drug treatment. The authors conclude that a low GI diet can be an effective and reliable method to reduce migraine attacks.
Abstract
OBJECTIVES The role of dietary restriction in the management of patients with migraine is still a controversial topic in the headache field. The aim of this study was to evaluate the efficacy of dietary restriction on migraine attacks. METHODS Patients diagnosed with migraine without aura according to the International Classification of Headaches were enrolled. Our study included 350 migraine patients evaluated at the neurology headache outpatient clinic. They were randomly divided into two groups: diet group as the study group and medication group as the control group. We told migraine patients to make lifestyle changes, especially those with low glycemic index in the diet group. On the other hand, propranolol, amitriptyline, flunarizine, and topiramate were used for the prophylaxis in the medication group. The frequency and severity of attacks [using the visual analog scale (VAS)] were recorded before starting dietary restriction and 1 and 3 months after the dietary restriction. RESULTS There were 350 participants in this study. After 3 months, a total of 147 patients (male/female: 17/130, mean age: 34.7±5.9) were evaluated in the diet group. The control group consisted of 147 age- and sex-matched, randomly selected patients with migraine without aura. In the first month after dietary restriction, monthly attack frequency significantly decreased in both groups but not the VAS score. The mean scores of VAS significantly decreased later in the diet group compared with those in the medication group (after 3 months). CONCLUSION The results of the study revealed that low glycemic index diet intake can be an effective and reliable method to reduce migraine attacks.
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Type-4 Resistant Starch in Substitution for Available Carbohydrate Reduces Postprandial Glycemic Response and Hunger in Acute, Randomized, Double-Blind, Controlled Study.
Stewart, ML, Wilcox, ML, Bell, M, Buggia, MA, Maki, KC
Nutrients. 2018;10(2)
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Resistant starch is a combination of dietary fibre and carbohydrate that ‘resists’ digestion in the small intestine and is fermented in the large intestine by gut bacteria. It is associated with a number of health benefits, particularly the management of blood glucose levels. This small double-blind, randomised controlled trail allocated 36 healthy individuals (mostly female, average age 46 and BMI 26) to eat either a low-fibre scone or a scone with added resistant starch in the form of acid-hydrolyzed and heat treated maize starch. The response of blood glucose and blood insulin levels were measured, as well as participants feeling of fullness and intestinal comfort after eating the scones. The scone with the added resistant starch had significantly lower blood glucose (43-45% lower) and blood insulin (35-40% lower) levels after eating the scone, when compared to those eating the low-fibre scone. They also reported feeling fuller for longer and had no particular digestive symptoms. Whilst this is a small study, Nutrition Practitioners may want to investigate dietary sources of resistant starch when working with clients to balance blood glucose and insulin levels.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Based on the findings of the Predict Study, it is highly probable that the same meal will elicit a different glycaemic response in individuals with different gut microbial compositions.
- The gut microbiota, therefore, needs to be taken into consideration when assessing glycaemic responses to a meal.
- Healthcare practitioners may like to consider the use of resistant starches as an additional tool to balance blood sugar responses to a meal.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Dietary modulation of the gut microbiota impacts human health. This paper discusses the effects of a man-made type of resistant starch on the glycaemic response to a meal. Based on the initial findings of the Predict Study, it is highly probably that the same meal will elicit a different glycaemic (and wider metabolic) response in individuals with different gut microbial compositions. So this paper confirms the need to take the gut microbiota into consideration when assessing glycaemic responses to a meal, both in research and in clinical practice.
Clinical practice applications:
Not all fibres are equal, and not all starches are equal. Type 4 resistant starch is a novel addition to the already known types 1, 2, and 3 and provides with clinicians with an additional tool to balance their patient's blood sugar response to a meal based on the effect of resistant starch on the gut microbiota.
Considerations for future research:
Resistant starches are known for their ability to affect gut microbiota composition and short-chain fatty acid concentrations which, in turn, have the ability to modulate immune and metabolic functions in the host, including cholesterol, fasting glucose, glycosylated haemoglobin, and pro-inflammatory markers. Further studies on glycaemic and wider metabolic responses to a meal must take into consideration the effect of resistant starches on gut microbial composition. Not doing so may be skewing scientific findings.
Abstract
Resistant starch (RS) is a type of dietary fiber that has been acknowledged for multiple physiological benefits. Resistant starch type 4 (RS4) is a subcategory of RS that has been more intensively studied as new types of RS4 emerge in the food supply. The primary aim of this randomized, double-blind, controlled study was to characterize the postprandial glucose response in healthy adults after consuming a high fiber scone containing a novel RS4 or a low fiber control scone without RS4. Secondary aims included assessment of postprandial insulin response, postprandial satiety, and gastrointestinal tolerance. The fiber scone significantly reduced postprandial glucose and insulin incremental areas under the curves (43-45% reduction, 35-40% reduction, respectively) and postprandial glucose and insulin maximum concentrations (8-10% and 22% reduction, respectively). The fiber scone significantly reduced hunger and desire to eat during the 180 min following consumption and yielded no gastrointestinal side effects compared with the control scone. The results from this study demonstrate that a ready-to-eat baked-good, such as a scone, can be formulated with RS4 replacing refined wheat flour to yield statistically significant and clinically meaningful reductions in blood glucose and insulin excursions. This is the first study to report increased satiety after short-term RS4 intake, which warrants further investigation in long-term feeding studies.
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Effects of Providing High-Fat versus High-Carbohydrate Meals on Daily and Postprandial Physical Activity and Glucose Patterns: a Randomised Controlled Trial.
Parr, EB, Devlin, BL, Callahan, MJ, Radford, BE, Blankenship, JM, Dunstan, DW, Hawley, JA
Nutrients. 2018;10(5)
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The timing of habitual meal consumption and composition is known to be an important factor in health status, particularly for blood glucose regulation. The aim of this randomised crossover study was to assess the effects of altering meal timing and diet composition on postprandial glucose and physical activity levels. Eight overweight or obese men with a sedentary lifestyle completed two 12-day measurement periods including a 7-day habitual period followed by a 5-day experimental period, with an 8-day washout period. The two conditions tested were a high-fat, low carbohydrate diet (HFD) and a high-carbohydrate, low-fat diet (HCD) and participants were instructed to consume meals at standardised times throughout both conditions. Body composition, oxygen consumption and blood glucose were measured at baseline and between each experimental condition. This trial found the provision of meals did not alter overall activity patterns or postprandial activity patterns. The authors observed increased sedentary activity across the day, and identify evening time as an important target for sedentary time to be minimised. Based on these results, the authors suggest that future dietary interventions consider habitual meal consumption and composition to best replicate real-world behaviours.
Abstract
We determined the effects of altering meal timing and diet composition on temporal glucose homeostasis and physical activity measures. Eight sedentary, overweight/obese men (mean ± SD, age: 36 ± 4 years; BMI: 29.8 ± 1.8 kg/m²) completed two × 12-day (12-d) measurement periods, including a 7-d habitual period, and then 5 d of each diet (high-fat diet [HFD]: 67:15:18% fat:carbohydrate:protein versus high-carbohydrate diet [HCD]: 67:15:18% carbohydrate:fat:protein) of three meals/d at ±30 min of 0800 h, 1230 h, and 1800 h, in a randomised order with an 8-d washout. Energy intake (EI), the timing of meal consumption, blood glucose regulation (continuous glucose monitor system (CGMS)), and activity patterns (accelerometer and inclinometer) were assessed across each 12-d period. Meal provision did not alter the patterns of reduced physical activity, and increased sedentary behaviour following dinner, compared with following breakfast and lunch. The HCD increased peak (+1.6 mmol/L, p < 0.001), mean (+0.5 mmol/L, p = 0.001), and total area under the curve (+670 mmol/L/min, p = 0.001), as well as 3-h postprandial meal glucose concentrations (all p < 0.001) compared with the HFD. In overweight/obese males, the provision of meals did not alter physical activity patterns, but did affect glycaemic control. Greater emphasis on meal timing and composition is required in diet and/or behaviour intervention studies to ensure relevance to real-world behaviours.