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Behavioral Weight Loss Intervention for Migraine: A Randomized Controlled Trial.
Bond, DS, Thomas, JG, Lipton, RB, Roth, J, Pavlovic, JM, Rathier, L, O'Leary, KC, Evans, EW, Wing, RR
Obesity (Silver Spring, Md.). 2018;26(1):81-87
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Migraine is a neurological disease characterized by moderate-to-severe headache and accompanying autonomic, affective, and sensory features. It is also comorbid with several diseases, including obesity. The aim of this study was to assess the impact of a standardized behavioural weight loss (BWL) intervention on migraine headache frequency. This study is a parallel-group, single-blinded randomised controlled trail. The participants were randomized to one of the two groups: BWL or migraine education (ME). Results show that changes in migraine headache frequency at post-treatment and follow-up were not significantly different between the BWL and ME control interventions. In fact, both BWL and ME had significant reductions in monthly migraine headache days from baseline to post-treatment and follow-up. Authors conclude that further research is required to better understand treatment mechanisms and whether BWL can enhance effects of standard pharmacologic and/or non-pharmacologic migraine therapies in patients with comorbid overweight/obesity.
Abstract
OBJECTIVE The objective of this study was to test whether behavioral weight loss (BWL) intervention decreases headaches in women with comorbid migraine and overweight or obesity. METHODS This randomized, single-blind trial allocated women 18 to 50 years old with 4 to 20 migraine days per month and a BMI = 25.0-49.9 kg/m2 to 16 weeks of BWL (n = 54), which targeted exercise and eating behaviors for weight loss, or to migraine education control (ME, n = 56), which delivered didactic instruction on migraine and treatments. Participants completed a 4-week smartphone headache diary at baseline, posttreatment (16-20 wk), and follow-up (32-36 wk). The primary outcome was posttreatment change in migraine days per month, analyzed via linear mixed effects models. RESULTS Of 110 participants randomly assigned, 85 (78%) and 80 (73%) completed posttreatment and follow-up. Although the BWL group achieved greater weight loss (mean [95% CI] in kilograms) than the ME group at posttreatment (-3.8 [-2.5 to -5.0] vs. + 0.9 [-0.4 to 2.2], P < 0.001) and follow-up (-3.2 [-2.0 to -4.5] vs. + 1.1 [-0.2 to 2.4], P < 0.001), there were no significant group (BWL vs. ME) differences (mean [95% CI]) in migraine days per month at posttreatment (-3.0 [-2.0 to -4.0] vs. -4.0 [-2.9 to -5.0], P = 0.185) or follow-up (-3.8 [-2.7 to -4.8] vs. -4.4 [-3.4 to -5.5], P = 0.378). CONCLUSIONS Contrary to hypotheses, BWL and ME yielded similar, sustained reductions in migraine headaches. Future research should evaluate whether adding BWL to standard pharmacological and/or nonpharmacological migraine treatment approaches yields greater benefits.
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Effect of a lifestyle intervention in obese infertile women on cardiometabolic health and quality of life: A randomized controlled trial.
van Dammen, L, Wekker, V, van Oers, AM, Mutsaerts, MAQ, Painter, RC, Zwinderman, AH, Groen, H, van de Beek, C, Muller Kobold, AC, Kuchenbecker, WKH, et al
PloS one. 2018;13(1):e0190662
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Obesity is linked to increase in cardiovascular and related disease risk factors. The rate of prevalence of obesity in childbearing women is on the increase. Based on these data one of the largest randomised control multicentre Lifestyle study was conducted. The aim of this study was to look into the effects of lifestyle intervention on cardio metabolic risk factors in childbearing obese women. The intervention goal was weight loss of 5-10% within six month. The intervention included caloric restriction and moderate physical activity. The result from the study showed lifestyle intervention among obese infertile women improved cardio metabolic health and also their physical quality of life. The authors concluded that based on data from this study infertile obese women, especially prior to infertility treatment, should be informed of the positive effects of lifestyle intervention of diet and physical activity.
Abstract
BACKGROUND The prevalence of obesity, an important cardiometabolic risk factor, is rising in women. Lifestyle improvements are the first step in treatment of obesity, but the success depends on factors like timing and motivation. Women are especially receptive to advice about lifestyle before and during pregnancy. Therefore, we hypothesize that the pre-pregnancy period provides the perfect window of opportunity to improve cardiometabolic health and quality of life of obese infertile women, by means of a lifestyle intervention. METHODS AND FINDINGS Between 2009-2012, 577 infertile women between 18 and 39 years of age, with a Body Mass Index of ≥ 29 kg/m2, were randomized to a six month lifestyle intervention preceding infertility treatment, or to direct infertility treatment. The goal of the intervention was 5-10% weight loss or a BMI < 29 kg/m2. Cardiometabolic outcomes included weight, waist- and hip circumference, body mass index, systolic and diastolic blood pressure, fasting glucose and insulin, HOMA-IR, hs-CRP, lipids and metabolic syndrome. All outcomes were measured by research nurses at randomization, 3 and 6 months. Self-reported quality of life was also measured at 12 months. Three participants withdrew their informed consent, and 63 participants discontinued the intervention program. Intention to treat analysis was conducted. Mixed effects regression models analyses were performed. Results are displayed as estimated mean differences between intervention and control group. Weight (-3.1 kg 95% CI: -4.0 to -2.2 kg; P < .001), waist circumference (-2.4 cm 95% CI: -3.6 to -1.1 cm; P < .001), hip circumference (-3.0 95% CI: -4.2 to -1.9 cm; P < .001), BMI (-1.2 kg/m2 95% CI: -1.5 to -0.8 kg/m2; P < .001), systolic blood pressure (-2.8 mmHg 95% CI: -5.0 to -0.7 mmHg; P = .01) and HOMA-IR (-0.5 95% CI: -0.8 to -0.1; P = .01) were lower in the intervention group compared to controls. Hs-CRP and lipids did not differ between groups. The odds ratio for metabolic syndrome in the intervention group was 0.53 (95% CI: 0.33 to 0.85; P < .01) compared to controls. Physical QoL scores were higher in the lifestyle intervention group (2.2 95% CI: 0.9 to 3.5; P = .001) while mental QoL scores did not differ. CONCLUSIONS In obese infertile women, a lifestyle intervention prior to infertility treatment improves cardiometabolic health and self-reported physical quality of life (LIFEstyle study: Netherlands Trial Register: NTR1530).
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Vitamin D Supplementation in Pregnancy and Lactation and Infant Growth.
Roth, DE, Morris, SK, Zlotkin, S, Gernand, AD, Ahmed, T, Shanta, SS, Papp, E, Korsiak, J, Shi, J, Islam, MM, et al
The New England journal of medicine. 2018;379(6):535-546
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In Bangladesh, 30% of newborns are small for gestational age and 36% of children under 5-years of age have stunted growth. Some previous studies suggest that supplementing mums-to-be with vitamin D during and/or after pregnancy may improve foetal and infant growth. The aim of this trial was to evaluate the dose-dependent effects of vitamin D supplementation on infant growth in Bangladesh. Over 1,100 pregnant women were split into five groups. One group received no vitamin D (placebo group). Three groups received supplementation from mid pregnancy in doses of 4200 IU, 16,800 IU, and 28,000 IU per week. The fifth group received 28,000 IU vitamin D per week during pregnancy, as well as 28,000 IU weekly for 26 weeks after childbirth. At the start of the study, 64% of women were vitamin D deficient (defined as 25(OH)D<30 nmol/L). The vitamin D status of the women was similar across the groups. Among 1,164 infants assessed at 1 year of age, there were no significant differences across groups in the length-for-age scores. Other anthropometric measures, birth outcomes, and morbidity did not differ significantly across groups. The researchers concluded that maternal vitamin D supplementation from mid pregnancy until birth or until 6 months post-partum did not improve foetal or infant growth. The findings of the study do not support routine vitamin D supplementation in pregnancy or lactation to improve birth outcomes or infant growth, even in communities with endemic vitamin D deficiency and foetal-infant growth restriction.
Abstract
BACKGROUND It is unclear whether maternal vitamin D supplementation during pregnancy and lactation improves fetal and infant growth in regions where vitamin D deficiency is common. METHODS We conducted a randomized, double-blind, placebo-controlled trial in Bangladesh to assess the effects of weekly prenatal vitamin D supplementation (from 17 to 24 weeks of gestation until birth) and postpartum vitamin D supplementation on the primary outcome of infants' length-for-age z scores at 1 year according to World Health Organization (WHO) child growth standards. One group received neither prenatal nor postpartum vitamin D (placebo group). Three groups received prenatal supplementation only, in doses of 4200 IU (prenatal 4200 group), 16,800 IU (prenatal 16,800 group), and 28,000 IU (prenatal 28,000 group). The fifth group received prenatal supplementation as well as 26 weeks of postpartum supplementation in the amount of 28,000 IU (prenatal and postpartum 28,000 group). RESULTS Among 1164 infants assessed at 1 year of age (89.5% of 1300 pregnancies), there were no significant differences across groups in the mean (±SD) length-for-age z scores. Scores were as follows: placebo, -0.93±1.05; prenatal 4200, -1.11±1.12; prenatal 16,800, -0.97±0.97; prenatal 28,000, -1.06±1.07; and prenatal and postpartum 28,000, -0.94±1.00 (P=0.23 for a global test of differences across groups). Other anthropometric measures, birth outcomes, and morbidity did not differ significantly across groups. Vitamin D supplementation had expected effects on maternal and infant serum 25-hydroxyvitamin D and calcium concentrations, maternal urinary calcium excretion, and maternal parathyroid hormone concentrations. There were no significant differences in the frequencies of adverse events across groups, with the exception of a higher rate of possible hypercalciuria among the women receiving the highest dose. CONCLUSIONS In a population with widespread prenatal vitamin D deficiency and fetal and infant growth restriction, maternal vitamin D supplementation from midpregnancy until birth or until 6 months post partum did not improve fetal or infant growth. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT01924013 .).
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Effect of ubiquinol supplementation on biochemical and oxidative stress indexes after intense exercise in young athletes.
Orlando, P, Silvestri, S, Galeazzi, R, Antonicelli, R, Marcheggiani, F, Cirilli, I, Bacchetti, T, Tiano, L
Redox report : communications in free radical research. 2018;23(1):136-145
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Strenuous exercise or overtraining increases the production of reactive oxygen species (ROS), especially in mitochondria. ROS production in excess leads to oxidative stress, cellular dysfunction, and oxidation of molecules such as DNA, polyunsaturated fatty acids, amino acids, and proteins. Previous research has shown that antioxidant supplementation might lead to the downregulation of ROS production. Coenzyme Q10 is an antioxidant believed to be effective in downregulating the effects of oxidative stress and preventing cellular damage. However, most previous studies have used ubiquinone, an oxidised form of Coenzyme Q10. Ubiquinol, a reduced form of Coenzyme Q10, is highly bioavailable, stable and in a form that the body can readily use. This randomised, double-blinded, crossover-controlled trial investigated ubiquinol's antioxidant and anti-inflammatory effects on biochemical and oxidative stress indexes after an intense bout of exercise in trained athletes. Twenty-one male athletes in constant training were randomly taking 200 mg/day of ubiquinol for a month. After a single bout of intense aerobic and endurance exercise, the participants showed a rapid and significant reduction in ubiquinol levels, especially lipoprotein CoQ10 and increased muscle damage markers such as Creatine kinase (CK) and Myoglobin (Mb). Ubiquinol supplementation prevented exercise-induced CoQ10 scarcity and reduced the activity of paraoxonase, an anti-inflammatory and antioxidant enzyme protective against oxidative stress in lipoprotein and circulating cells. Ubiquinol supplementation was associated with a significant decrease in cytosolic ROS in peripheral blood mononuclear cells. Ubiquinol supplementation enhanced plasma and cellular antioxidant levels. Healthcare professionals can use the results of this study to understand the antioxidant effects of ubiquinol supplementation and its buffering effect on plasma CoQ10 balances and exercise-induced CoQ10 depletion. However, further robust studies are required to evaluate the therapeutic potential of ubiquinol supplementation in sports nutrition.
Abstract
OBJECTIVES Physical exercise significantly impacts the biochemistry of the organism. Ubiquinone is a key component of the mitochondrial respiratory chain and ubiquinol, its reduced and active form, is an emerging molecule in sport nutrition. The aim of this study was to evaluate the effect of ubiquinol supplementation on biochemical and oxidative stress indexes after an intense bout of exercise. METHODS 21 male young athletes (26 + 5 years of age) were randomized in two groups according to a double blind cross-over study, either supplemented with ubiquinol (200 mg/day) or placebo for 1 month. Blood was withdrawn before and after a single bout of intense exercise (40 min run at 85% maxHR). Physical performance, hematochemical parameters, ubiquinone/ubiquinol plasma content, intracellular reactive oxygen species (ROS) level, mitochondrial membrane depolarization, paraoxonase activity and oxidative DNA damage were analyzed. RESULTS A single bout of intense exercise produced a significant increase in most hematochemical indexes, in particular CK and Mb while, on the contrary, normalized coenzyme Q10 plasma content decreased significantly in all subjects. Ubiquinol supplementation prevented exercise-induced CoQ deprivation and decrease in paraoxonase activity. Moreover at a cellular level, in peripheral blood mononuclear cells, ubiquinol supplementation was associated with a significant decrease in cytosolic ROS while mitochondrial membrane potential and oxidative DNA damage remained unchanged. DISCUSSION Data highlights a very rapid dynamic of CoQ depletion following intense exercise underlying an increased demand by the organism. Ubiquinol supplementation minimized exercise-induced depletion and enhanced plasma and cellular antioxidant levels but it was not able to improve physical performance indexes or markers of muscular damage.
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Metabolic Slowing and Reduced Oxidative Damage with Sustained Caloric Restriction Support the Rate of Living and Oxidative Damage Theories of Aging.
Redman, LM, Smith, SR, Burton, JH, Martin, CK, Il'yasova, D, Ravussin, E
Cell metabolism. 2018;27(4):805-815.e4
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Following a calorie-restricted diet while maintaining adequate nutrition is known to have a beneficial effect on increasing longevity and promoting healthy ageing. Oxidative stress resulting from reactive oxygen species formation in mitochondria plays a role in accelerating ageing by damaging DNA, proteins and lipids. A calorie-restriction diet can reduce oxidative stress and cause metabolic adaptations. In this ancillary study, non-obese participants were randomly assigned to either a calorie restriction group which followed 25% calorie restriction while getting adequate nutritional support through supplementation or to a control group which included ad libitum calorie intake. After 2 years of intervention, participants in the calorie restriction group achieved 15% calorie restriction, 8.7kg weight loss and a reduction in 24-hour energy expenditure and sleep energy expenditure beyond weight loss because of metabolic adaptation. Oxidative stress and thyroid axis activity were also reduced in the calorie restriction group. Further robust studies are required to evaluate the effectiveness of calorie restriction in metabolic adaptation and oxidative stress and its effects on ageing. The results of this study can be used by healthcare professionals to understand the benefits of a nutritionally adequate calorie restriction diet on adjusting metabolic processes.
Abstract
Calorie restriction (CR) is a dietary intervention with potential benefits for healthspan improvement and lifespan extension. In 53 (34 CR and 19 control) non-obese adults, we tested the hypothesis that energy expenditure (EE) and its endocrine mediators are reduced with a CR diet over 2 years. Approximately 15% CR was achieved over 2 years, resulting in an average 8.7 kg weight loss, whereas controls gained 1.8 kg. In the CR group, EE measured over 24 hr or during sleep was approximately 80-120 kcal/day lower than expected on the basis of weight loss, indicating sustained metabolic adaptation over 2 years. This metabolic adaptation was accompanied by significantly reduced thyroid axis activity and reactive oxygen species (F2-isoprostane) production. Findings from this 2-year CR trial in healthy, non-obese humans provide new evidence of persistent metabolic slowing accompanied by reduced oxidative stress, which supports the rate of living and oxidative damage theories of mammalian aging.
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The Effect of Gluten Free Diet on Components of Metabolic Syndrome: A Randomized Clinical Trial
Ehteshami, M, Shakerhosseini, R, Sedaghat, F, Hedayati, M, Eini-Zinab, H, Hekmatdoost, A
Asian Pacific journal of cancer prevention : APJCP. 2018;19(10):2979-2984
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Metabolic syndrome is a cluster of conditions related to cardiovascular disorders risk factors such as blood pressure, dyslipidaemia, hyperglycaemia, excess body fat around the waist and insulin resistance. The aim of this study was to assess the effects of a gluten-free diet on components of metabolic syndrome in patients diagnosed with metabolic syndrome. The study is a randomised control trial that recruited fifty subjects diagnosed with metabolic syndrome. Subjects were block randomised by gender into control and gluten-free diet groups. Results showed that a gluten-free diet induces significant reduction in waist circumference in comparison to control diet. Reduction in waist circumference without significant reduction in body weight may indicate preferential loss of abdominal fat. Furthermore, results indicate that a gluten-free diet improved glucose tolerance. Authors conclude that a gluten-free diet significantly improved some key features of metabolic syndrome including blood glucose and serum triglycerides.
Abstract
Background: This study aimed to assess the effects of Gluten free diet (GFD) on components of metabolic syndrome (MES). Materials and Methods: In this randomized clinical trial, 50 subjects diagnosed with MES were randomly divided into two groups (n=25). The first group received a GFD and the second group continued their regular diet. Biochemical markers of MES and blood pressure were measured before and after 8-week intervention. Results: Forty five subjects completed the study. A post-hoc comparison of the groups showed no effects of the GFD and control diet on LDL cholesterol, total cholesterol, fasting insulin, HOMA-IR, systolic and diastolic blood pressure levels. The GFD reduced fasting blood glucose, waist circumference (WC) and serum triglyceride concentration significantly compared with the control diet (p<0.05). Conclusion: Short-term GFD reduced WC and improved glycemic control and Triglyceride level in subjects with the metabolic syndrome.
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Impact of Experimentally Induced Cognitive Dietary Restraint on Eating Behavior Traits, Appetite Sensations, and Markers of Stress during Energy Restriction in Overweight/Obese Women.
Morin, I, Bégin, C, Maltais-Giguère, J, Bédard, A, Tchernof, A, Lemieux, S
Journal of obesity. 2018;2018:4259389
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The treatment of obesity has become a public health priority given the negative impact of this condition on physical and mental health. The aim of this study was to compare the effects of energy restriction alone or in combination with induced cognitive dietary restraint (CDR) on eating behaviour traits, appetite sensations, and markers of stress in overweight and obese premenopausal women. The study is a single-blinded randomised clinical study which recruited premenopausal women aged between 26 and 50 years. The participants were randomised to either an energy-restriction-plus-induced CDR condition (CDR+group) or an energy-restriction-without induced CDR condition (CDR−group). Results indicate that inducing CDR in a context of energy restriction had no further effects on eating behaviour traits, appetite sensations, and markers of stress in the short term as well as in the longer term than energy restriction alone. Authors conclude that increasing CDR has no negative impact on factors regulating energy balance in the context of energy restriction.
Abstract
Weight loss has been associated with changes in eating behaviors and appetite sensations that favor a regain in body weight. Since traditional weight loss approaches emphasize the importance of increasing cognitive dietary restraint (CDR) to achieve negative energy imbalance, it is difficult to untangle the respective contributions of energy restriction and increases in CDR on factors that can eventually lead to body weight regain. The present study aimed at comparing the effects of energy restriction alone or in combination with experimentally induced CDR on eating behavior traits, appetite sensations, and markers of stress in overweight and obese women. We hypothesized that the combination of energy restriction and induced CDR would lead to more prevalent food cravings, increased appetite sensations, and higher cortisol concentrations than when energy restriction is not coupled with induced CDR. A total of 60 premenopausal women (mean BMI: 32.0 kg/m2; mean age: 39.4 y) were provided with a low energy density diet corresponding to 85% of their energy needs during a 4-week fully controlled period. At the same time, women were randomized to either a condition inducing an increase in CDR (CDR+ group) or a condition in which CDR was not induced (CRD- group). Eating behavior traits (Three-Factor Eating Questionnaire and Food Craving Questionnaire), appetite sensations (after standardized breakfast), and markers of stress (Perceived Stress Scale; postawakening salivary cortisol) were measured before (T = 0 week) and after (T = 4 weeks) the 4-week energy restriction, as well as 3 months later. There was an increase in CDR in the CDR+ group while no such change was observed in the CDR- group (p=0.0037). No between-group differences were observed for disinhibition, hunger, cravings, appetite sensations, perceived stress, and cortisol concentrations. These results suggest that a slight increase in CDR has no negative impact on factors regulating energy balance in the context of energy restriction.
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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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Randomised trial of coconut oil, olive oil or butter on blood lipids and other cardiovascular risk factors in healthy men and women.
Khaw, KT, Sharp, SJ, Finikarides, L, Afzal, I, Lentjes, M, Luben, R, Forouhi, NG
BMJ open. 2018;8(3):e020167
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Blood lipids is a term used for fatty substances found in the blood such as cholesterol and triglycerides. When these fatty substances are above a normal level it may increase an individual’s risk factors for coronary heart diseases. A diet high in saturated fats is linked to an increased amount of these fats in the blood. Recent renewed interest in the health effects of saturated fats based on their composition (long chain, medium chain, and short chain) brought about this randomised control trial. The aim of the study was to compare the effects of butter, extra virgin coconut oil and olive oil on blood lipids. The study population were men and women aged between 50 and 70 years who did not have any known medical history of heart disease or were on any medication related to heart disease. At the end of the four week trial period, significant changes in the blood lipids were observed within the three intervention groups. The concentration of LDL cholesterol in the butter group when compared with coconut oil and olive oil showed a significant increase, whilst no difference was observed in the LDL cholesterol concentration between the olive oil and coconut oil group. The concentration of HDL cholesterol in the coconut oil group increased significantly in comparison to the butter or olive oil group. However, the authors concluded that as further trials between different fatty acids and health are required, the current recommendation of the American Heart Association - to reduce saturated fat in general - is strongly recommended.
Abstract
INTRODUCTION High dietary saturated fat intake is associated with higher blood concentrations of low-density lipoprotein cholesterol (LDL-C), an established risk factor for coronary heart disease. However, there is increasing interest in whether various dietary oils or fats with different fatty acid profiles such as extra virgin coconut oil may have different metabolic effects but trials have reported inconsistent results. We aimed to compare changes in blood lipid profile, weight, fat distribution and metabolic markers after four weeks consumption of 50 g daily of one of three different dietary fats, extra virgin coconut oil, butter or extra virgin olive oil, in healthy men and women in the general population. DESIGN Randomised clinical trial conducted over June and July 2017. SETTING General community in Cambridgeshire, UK. PARTICIPANTS Volunteer adults were recruited by the British Broadcasting Corporation through their websites. Eligibility criteria were men and women aged 50-75 years, with no known history of cancer, cardiovascular disease or diabetes, not on lipid lowering medication, no contraindications to a high-fat diet and willingness to be randomised to consume one of the three dietary fats for 4 weeks. Of 160 individuals initially expressing an interest and assessed for eligibility, 96 were randomised to one of three interventions; 2 individuals subsequently withdrew and 94 men and women attended a baseline assessment. Their mean age was 60 years, 67% were women and 98% were European Caucasian. Of these, 91 men and women attended a follow-up assessment 4 weeks later. INTERVENTION Participants were randomised to extra virgin coconut oil, extra virgin olive oil or unsalted butter and asked to consume 50 g daily of one of these fats for 4 weeks, which they could incorporate into their usual diet or consume as a supplement. MAIN OUTCOMES AND MEASURES The primary outcome was change in serum LDL-C; secondary outcomes were change in total and high-density lipoprotein cholesterol (TC and HDL-C), TC/HDL-C ratio and non-HDL-C; change in weight, body mass index (BMI), waist circumference, per cent body fat, systolic and diastolic blood pressure, fasting plasma glucose and C reactive protein. RESULTS LDL-C concentrations were significantly increased on butter compared with coconut oil (+0.42, 95% CI 0.19 to 0.65 mmol/L, P<0.0001) and with olive oil (+0.38, 95% CI 0.16 to 0.60 mmol/L, P<0.0001), with no differences in change of LDL-C in coconut oil compared with olive oil (-0.04, 95% CI -0.27 to 0.19 mmol/L, P=0.74). Coconut oil significantly increased HDL-C compared with butter (+0.18, 95% CI 0.06 to 0.30 mmol/L) or olive oil (+0.16, 95% CI 0.03 to 0.28 mmol/L). Butter significantly increased TC/HDL-C ratio and non-HDL-C compared with coconut oil but coconut oil did not significantly differ from olive oil for TC/HDL-C and non-HDL-C. There were no significant differences in changes in weight, BMI, central adiposity, fasting blood glucose, systolic or diastolic blood pressure among any of the three intervention groups. CONCLUSIONS AND RELEVANCE Two different dietary fats (butter and coconut oil) which are predominantly saturated fats, appear to have different effects on blood lipids compared with olive oil, a predominantly monounsaturated fat with coconut oil more comparable to olive oil with respect to LDL-C. The effects of different dietary fats on lipid profiles, metabolic markers and health outcomes may vary not just according to the general classification of their main component fatty acids as saturated or unsaturated but possibly according to different profiles in individual fatty acids, processing methods as well as the foods in which they are consumed or dietary patterns. These findings do not alter current dietary recommendations to reduce saturated fat intake in general but highlight the need for further elucidation of the more nuanced relationships between different dietary fats and health. TRIAL REGISTRATION NUMBER NCT03105947; Results.