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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.
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Effect of intermittent vs. daily calorie restriction on changes in weight and patient-reported outcomes in people with multiple sclerosis.
Fitzgerald, KC, Vizthum, D, Henry-Barron, B, Schweitzer, A, Cassard, SD, Kossoff, E, Hartman, AL, Kapogiannis, D, Sullivan, P, Baer, DJ, et al
Multiple sclerosis and related disorders. 2018;23:33-39
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Multiple sclerosis (MS) is a disease of the central nervous system. Dietary modification is emerging as a safe intervention to potentially modify disease course. The main aim of this study was to assess the safety and feasibility of an intermittent fasting diet in people with MS. Secondary outcomes explored the effects of calorie restriction (CR) diets on body weight and anthropometric characteristics as well as on patient-reported outcomes including fatigue, sleep and mood. The study is a pilot randomised controlled feeding study of three different types of diets. Each participant (n=36) was randomized to 1 of 3 diets: a control diet (placebo), a daily CR diet and intermittent CR diet. Results indicate that daily CR diet was associated with marginally greater weight loss than the intermittent CR diet. Both CR diets were associated with trends toward improvements in cardiometabolic outcomes. Furthermore, CR diets were associated with in improvements in emotional well-being. Authors conclude that CR and weight loss represent interventions for clinically relevant symptoms due to MS, such as emotional well-being, without adding meaningful risks or adverse outcomes.
Abstract
An intermittent fasting or calorie restriction diet has favorable effects in the mouse forms of multiple sclerosis (MS) and may provide additional anti-inflammatory and neuroprotective advantages beyond benefits obtained from weight loss alone. We conducted a pilot randomized controlled feeding study in 36 people with MS to assess safety and feasibility of different types of calorie restriction (CR) diets and assess their effects on weight and patient reported outcomes in people with MS. Patients were randomized to receive 1 of 3 diets for 8 weeks: daily CR diet (22% daily reduction in energy needs), intermittent CR diet (75% reduction in energy needs, 2 days/week; 0% reduction, 5 days/week), or a weight-stable diet (0% reduction in energy needs, 7 days/week). Of the 36 patients enrolled, 31 (86%) completed the trial; no significant adverse events occurred. Participants randomized to CR diets lost a median 3.4 kg (interquartile range [IQR]: -2.4, -4.0). Changes in weight did not differ significantly by type of CR diet, although participants randomized to daily CR tended to have greater weight loss (daily CR: -3.6 kg [IQR: -3.0, -4.1] vs. intermittent CR: -3.0 kg [IQR: -1.95, -4.1]; P = 0.15). Adherence to study diets differed significantly between intermittent CR vs. daily CR, with lesser adherence observed for intermittent CR (P = 0.002). Randomization to either CR diet was associated with significant improvements in emotional well-being/depression scores relative to control, with an average 8-week increase of 1.69 points (95% CI: 0.72, 2.66). CR diets are a safe/feasible way to achieve weight loss in people with MS and may be associated with improved emotional health.
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Elevated methane levels in small intestinal bacterial overgrowth suggests delayed small bowel and colonic transit.
Suri, J, Kataria, R, Malik, Z, Parkman, HP, Schey, R
Medicine. 2018;97(21):e10554
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Whilst the most conclusive way to diagnose SIBO is to use an invasive procedure (endoscopy) to take samples from the middle section of the small intestine (jejunum), lactulose breath testing of methane and hydrogen gasses has become the most commonly used test to rule SIBO in or out. This cohort study used historic data (retrospective) of 78 individuals to compare intestinal transit time in patients with a positive lactulose breath test to those with a negative result, as well as compare patients with hydrogen-positive results with those with methane-positive results. All patients experienced gastrointestinal (GI) symptoms of nausea, bloating, constipation, diarrhea and gas to varying degrees. No significant difference in GI symptom severity was found between those with a positive lactulose breath test and those with a negative result. However, those with a hydrogen-gas positive result had a significantly higher level of reported nausea compared to the methane-gas positive patients. A positive SIBO result on the breath test also did not affect GI transit time in comparison to a negative result. However, those with a methane-gas peak on their positive lactulose breath test had a statistically significant slower GI transit time when compared to those with a hydrogen-positive result.
Abstract
Limited research exists regarding the relationship between small intestinal bacterial overgrowth (SIBO), small bowel transit (SBT), and colonic transit (CT). Furthermore, symptom analysis is limited between the subtypes of SIBO hydrogen producing (H-SIBO) and methane producing (M-SIBO). The primary aims of this study are to: compare the SBT and CT in patients with a positive lactulose breath test (LBT) to those with a normal study; compare the SBT and CT among patients with H-SIBO or M-SIBO; compare the severity of symptoms in patients with a positive LBT to those with a normal study; compare the severity of symptoms among patients with H-SIBO or M-SIBO.A retrospective review was performed for 89 patients who underwent a LBT and whole gut transit scintigraphy (WGTS) between 2014 and 2016. Seventy-eight patients were included. WGTS evaluated gastric emptying, SBT (normal ≥40% radiotracer bolus accumulated at the ileocecal valve at 6 hours), and CT (normal geometric center of colonic activity = 1.6-7.0 at 24 hours, 4.0-7.0 at 48 hours, 6.2-7.0 at 72 hours; elevated geometric center indicates increased transit). We also had patients complete a pretest symptom survey to evaluate nausea, bloating, constipation, diarrhea, belching, and flatulence.A total of 78 patients (69 females, 9 males, mean age of 48 years, mean BMI of 25.9) were evaluated. Forty-seven patients had a positive LBT (H-SIBO 66%, M-SIBO 34%). Comparison of SBT among patients with a positive LBT to normal LBT revealed no significant difference (62.1% vs 58.6%, P = .63). The mean accumulated radiotracer was higher for H-SIBO compared to M-SIBO (71.5% vs 44.1%; P < .05). For CT, all SIBO patients had no significant difference in geometric centers of colonic activity at 24, 48, and 72 hours when compared to the normal group. When subtyping, H-SIBO had significantly higher geometric centers compared to the M-SIBO group at 24 hours (4.4 vs 3.1, P < .001), 48 hours (5.2 vs 3.8, P = .002), and at 72 hours (5.6 vs 4.3, P = .006). The symptom severity scores did not differ between the positive and normal LBT groups. A higher level of nausea was present in the H-SIBO group when compared to the M-SIBO group.Overall, the presence of SIBO does not affect SBT or CT at 24, 48, and 72 hours. However, when analyzing the subtypes, M-SIBO has significantly more delayed SBT and CT when compared to H-SIBO. These results suggest the presence of delayed motility in patients with high methane levels on LBT.
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Acute Endothelial Benefits of Fat Restriction over Carbohydrate Restriction in Type 2 Diabetes Mellitus: Beyond Carbs and Fats.
Barbosa-Yañez, RL, Dambeck, U, Li, L, Machann, J, Kabisch, S, Pfeiffer, AFH
Nutrients. 2018;10(12)
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The control of type 2 diabetes mellitus has become a global challenge. Cardiovascular disease is a major cause of mortality in type 2 diabetes. The aim of the study is to examine and compare the effect of a hypocaloric very low carbohydrate diet versus hypocaloric low-fat diet on vascular function and visceral adipose tissue in type 2 diabetic patients. The study is a randomised parallel group intervention study with adult type 2 diabetes patients with an age range between 42 and 76 years. Results show that both dietary strategies effectively reduced body weight, total adipose tissue, visceral adipose tissue and lipid accumulation in the liver. However, participants following the low-fat diet experienced greater vascular function enhancements. Authors conclude that low-fat diet elicited advantageous effects on vascular function in patients with type 2 diabetes.
Abstract
BACKGROUND Cardiovascular diseases (CVD) are the major cause of mortality in type 2 diabetes patients (T2DM). The causes are embedded in a complex interplay between excess body fat, insulin resistance and serum lipid anomalies. Endothelial homeostasis is strongly affected by this pathogenic network. Even though metabolic changes and weight loss improve vascular endothelial function, the effect of different dietary approaches is still uncertain for type 2 diabetes patients. OBJECTIVE We aimed to compare the acute effects of a hypocaloric very low carbohydrate (VLC) diet versus a hypocaloric low fat (LF) diet on flow mediated dilation (FMD), intrahepatic lipid (IHL) accumulation and visceral adipose tissue as independent risk factors of CVD in T2DM patients. DESIGN 36 T2DM patients (age 63 ± 8 years, 60% females) were randomly assigned to the VLC diet (4⁻10% of total energy intake (E)) or to the LF diet (<30% E) for 3 weeks. Endothelial function was assessed by the flow mediated dilation (FMD) method. Adipose tissue depots and IHL were determined by magnetic resonance. RESULTS Both dietary strategies reduced body weight, body fat content and IHL. Unexpectedly, the LF group experienced significantly greater enhancement of FMD, compared to the VLC group. The FMD showed a positive correlation with protein intake and fat intake in the LF group, while it revealed a negative correlation with protein intake in the VLC diet group. CONCLUSIONS Reduction of total and hepatic adiposity was shown to be successful using either the VLC or LF hypocaloric diets, however, improvements in FMD may be related to the interplay of fat and protein intake.
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Changes in Visceral Adiposity, Subcutaneous Adiposity, and Sex Hormones in the Diabetes Prevention Program.
Kim, C, Dabelea, D, Kalyani, RR, Christophi, CA, Bray, GA, Pi-Sunyer, X, Darwin, CH, Yalamanchi, S, Barrett-Connor, E, Golden, SH, et al
The Journal of clinical endocrinology and metabolism. 2017;102(9):3381-3389
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It is not currently known to what extent changes in different types of fat stores (visceral fat that surrounds organs and subcutaneous fat that sits under the surface of the skin) relate to changes in sex hormones. This study was a secondary analysis of a randomised controlled trial including 555 individuals. It examined whether changes to visceral and subcutaneous fat were associated with changes in sex hormones (DHEA, testosterone, oestrogen and sex hormone binding globulin - SHBG) among overweight individuals with glucose intolerance under the care of a diabetes program. Participants were randomly assigned to an intensive lifestyle modification programme (goals for weight reduction and 150 mins exercise weekly), medication (metformin) or placebo for 12 months. The authors found that among men, reductions in both types of fat were associated with significant increases in total testosterone and SHBG. Among women, reductions in both types of fat were associated with increases in SHBG and associations with estrone differed by menopausal status. No associations were found between changes in fat stores and estradiol or DHEA. The authors conclude that weight loss may affect sex hormone profiles via reductions in visceral and subcutaneous fat. -
Abstract
Context: The degree to which changes in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) relate to corresponding changes in plasma sex steroids is not known. Objective: We examined whether changes in VAT and SAT areas assessed by computed tomography were associated with changes in sex hormones [dehydroepiandrosterone sulfate (DHEAS), testosterone, estradiol, estrone, and sex hormone binding globulin (SHBG)] among Diabetes Prevention Program participants. Design: Secondary analysis of a randomized trial. Participants: Overweight and glucose-intolerant men (n = 246) and women (n = 309). Interventions: Intensive lifestyle change with goals of weight reduction and 150 min/wk of moderate intensity exercise or metformin administered 850 mg twice a day or placebo. Main Outcome Measures: Associations between changes in VAT, SAT, and sex hormone changes over 1 year. Results: Among men, reductions in VAT and SAT were both independently associated with significant increases in total testosterone and SHBG in fully adjusted models. Among women, reductions in VAT and SAT were both independently associated with increases in SHBG and associations with estrone differed by menopausal status. Associations were similar by race/ethnicity and by randomization arm. No significant associations were observed between change in fat depot with change in estradiol or DHEAS. Conclusions: Among overweight adults with impaired glucose intolerance, reductions in either VAT and SAT were associated with increased total testosterone in men and higher SHBG in men and women. Weight loss may affect sex hormone profiles via reductions in visceral and subcutaneous fat.
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Limbic-thalamo-cortical projections and reward-related circuitry integrity affects eating behavior: A longitudinal DTI study in adolescents with restrictive eating disorders.
Olivo, G, Wiemerslage, L, Swenne, I, Zhukowsky, C, Salonen-Ros, H, Larsson, EM, Gaudio, S, Brooks, SJ, Schiöth, HB
PloS one. 2017;12(3):e0172129
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This is a highly specialised and technical observational study using brain imaging techniques to investigate longitudinal changes in the brain white matter micro-structure in adolescent patients with restrictive eating disorders (e.g. anorexia nervosa). Twelve patients and twenty-four controls were enrolled into this study. Patients were scanned at diagnosis and after one year of family-based treatment. Brain imaging results were correlated with weight/BMI as well as clinical features of the eating disorder. The observed changes in specific regions of the brain support the hypothesis that neural pathway related to taste processing and reward-related regions are involved, and determine an alteration in food-related cognitive processing in adolescents, leading to restrictive eating behaviour. The observed changes in brain micro-structure appeared to revert after one year of follow-up. This suggests that a prompt intervention might be effective in arresting the disruption of white matter integrity that occurs during the first phases of the eating disorder, and that early treatment is of particular importance in adolescents, as during adolescence processes relating to neuronal structuring and neuroplasticity are at their maximum.
Abstract
Few studies have used diffusion tensor imaging (DTI) to investigate the micro-structural alterations of WM in patients with restrictive eating disorders (rED), and longitudinal data are lacking. Twelve patients with rED were scanned at diagnosis and after one year of family-based treatment, and compared to twenty-four healthy controls (HCs) through DTI analysis. A tract-based spatial statistics procedure was used to investigate diffusivity parameters: fractional anisotropy (FA) and mean, radial and axial diffusivities (MD, RD and AD, respectively). Reduced FA and increased RD were found in patients at baseline in the corpus callosum, corona radiata and posterior thalamic radiation compared with controls. However, no differences were found between follow-up patients and controls, suggesting a partial normalization of the diffusivity parameters. In patients, trends for a negative correlation were found between the baseline FA of the right anterior corona radiata and the Eating Disorder Examination Questionnaire total score, while a positive trend was found between the baseline FA in the splenium of corpus callosum and the weight loss occurred between maximal documented weight and time of admission. A positive trend for correlation was also found between baseline FA in the right anterior corona radiata and the decrease in the Obsessive-Compulsive Inventory Revised total score over time. Our results suggest that the integrity of the limbic-thalamo-cortical projections and the reward-related circuitry are important for cognitive control processes and reward responsiveness in regulating eating behavior.
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Effect of Two-Year Caloric Restriction on Bone Metabolism and Bone Mineral Density in Non-Obese Younger Adults: A Randomized Clinical Trial.
Villareal, DT, Fontana, L, Das, SK, Redman, L, Smith, SR, Saltzman, E, Bales, C, Rochon, J, Pieper, C, Huang, M, et al
Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 2016;31(1):40-51
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While there is increasing evidence that caloric restriction (CR) can extend a healthy lifespan in humans, it is not known whether weight loss is linked to reductions in bone mineral density (BMD) in younger adults. The aim of this trial was to assess the effect of prolonged caloric restriction on bone mass density and bone metabolism in 218 healthy adults aged 21 to 40. Participants were randomised to either a 25% caloric restriction or ad libitum diet for two years. The findings of this study showed that the CR group had a larger increase in markers of bone turnover and caused a modest but significant decline in bone mineral density. Based on these findings, the authors suggest that further research is needed to determine whether bone loss increases fracture risk, and whether interventions can prevent bone loss that occurs with CR-induced weight loss.
Abstract
Although caloric restriction (CR) could delay biologic aging in humans, it is unclear if this would occur at the cost of significant bone loss. We evaluated the effect of prolonged CR on bone metabolism and bone mineral density (BMD) in healthy younger adults. Two-hundred eighteen non-obese (body mass index [BMI] 25.1 ± 1.7 kg/m(2) ), younger (age 37.9 ± 7.2 years) adults were randomly assigned to 25% CR (CR group, n = 143) or ad libitum (AL group, n = 75) for 2 years. Main outcomes were BMD and markers of bone turnover. Other outcomes included body composition, bone-active hormones, nutrient intake, and physical activity. Body weight (-7.5 ± 0.4 versus 0.1 ± 0.5 kg), fat mass (-5.3 ± 0.3 versus 0.4 ± 0.4 kg), and fat-free mass (-2.2 ± 0.2 versus -0.2 ± 0.2 kg) decreased in the CR group compared with AL (all between group p < 0.001). Compared with AL, the CR group had greater changes in BMD at 24 months: lumbar spine (-0.013 ± 0.003 versus 0.007 ± 0.004 g/cm(2) ; p < 0.001), total hip (-0.017 ± 0.002 versus 0.001 ± 0.003 g/cm(2) ; p < 0.001), and femoral neck (-0.015 ± 0.003 versus -0.005 ± 0.004 g/cm(2) ; p = 0.03). Changes in bone markers were greater at 12 months for C-telopeptide (0.098 ± 0.012 versus 0.025 ± 0.015 μg/L; p < 0.001), tartrate-resistant acid phosphatase (0.4 ± 0.1 versus 0.2 ± 0.1 U/L; p = 0.004), and bone-specific alkaline phosphatase (BSAP) (-1.4 ± 0.4 versus -0.3 ± 0.5 U/L; p = 0.047) but not procollagen type 1 N-propeptide; at 24 months, only BSAP differed between groups (-1.5 ± 0.4 versus 0.9 ± 0.6 U/L; p = 0.001). The CR group had larger increases in 25-hydroxyvitamin D, cortisol, and adiponectin and decreases in leptin and insulin compared with AL. However, parathyroid hormone and IGF-1 levels did not differ between groups. The CR group also had lower levels of physical activity. Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ∼31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span. Further long-term studies are needed to determine if CR-induced bone loss in healthy adults contributes to fracture risk and if bone loss can be prevented with exercise.
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Modifying influence of dietary sugar in the relationship between cortisol and visceral adipose tissue in minority youth.
Gyllenhammer, LE, Weigensberg, MJ, Spruijt-Metz, D, Allayee, H, Goran, MI, Davis, JN
Obesity (Silver Spring, Md.). 2014;22(2):474-81
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Visceral adipose tissue (VAT) is one of the strongest risk factors associated with obesity and related co-morbidities. A potential mechanism for this association involves cortisol and cortisol receptors, however the specific interaction of cortisol and diet upon fat deposition has not yet been explored in humans. The purpose of this cross-sectional study was to assess the impact of a high-fat, high-sugar diet on the association between stress and visceral fat in 165 overweight minority youth. The results of this study showed that cortisol was significantly associated with elevated VAT under conditions of high sugar intake in this population. Based on these findings, the authors conclude that dietary sugar may play a crucial role in moderating the adverse effects of cortisol.
Abstract
OBJECTIVE Cortisol has been associated with preferential visceral adipose tissue (VAT) deposition; however, findings in humans are mixed, which may be clarified when diet is considered. DESIGN AND METHODS Participants included 165 African-American and Latino, overweight adolescents (BMI% 97.2±3.2%, ages 13-18, 67% Latino, 66% female). Body composition was determined by dual energy X-ray absorptiometry, abdominal fat depots [VAT, subcutaneous (SAT)] by multiple-slice MRI, time-controlled serum sample to measure cortisol, and 2-day multi-pass 24-hour dietary recall. Linear regression analysis examined the cross-sectional relationship between cortisol, and the interaction of diet and cortisol on adiposity measures. Sex, race, age, and total body fat were a priori covariates. RESULTS There was a significant interaction between cortisol and sugar (total and added) in the prediction of VAT (P(interaction) ≤ 0.05). Amongst participants with high total or added-sugar intake, cortisol was significantly associated with VAT (ß = 0.031 P < 0.001; ß = 0.026 P < 0.001), with no relationship in low consumers of total or added-sugar. CONCLUSION Dietary sugar may play an important role in modifying the relationship between cortisol and VAT, such that cortisol is significantly associated with elevated VAT under conditions of high sugar intake.
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Nighttime snacking reduces whole body fat oxidation and increases LDL cholesterol in healthy young women.
Hibi, M, Masumoto, A, Naito, Y, Kiuchi, K, Yoshimoto, Y, Matsumoto, M, Katashima, M, Oka, J, Ikemoto, S
American journal of physiology. Regulatory, integrative and comparative physiology. 2013;304(2):R94-R101
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Night eating syndrome (NES) is defined by night time eating (25% or more of the total energy of the day is consumed after the evening meal or by waking up in the middle of the night to eat at least three times per week). Research suggests that it is associated with obesity and a higher BMI. Those with NES may have higher glucose and insulin levels, and lower levels of ghrelin during the night compared to those without NES. This randomised crossover study aimed to explore the impact of nighttime eating on energy, glucose and lipid metabolism in normal weight young women. Participants were asked to either complete a 2 week nighttime snacking intervention or a daytime snacking intervention. The snack represented 10% of the average energy requirement (1950 k/cal per day) with a protein:fat:carbohydrate ratio of 5:50:45. The study found no impact of nighttime snacking on body weight, energy expenditure or glucose metabolism compared to daytime snacking. However, it did find a decrease in fat oxidation and increases in total and LDL cholesterol. Hunger levels before lunch were also higher during the nighttime snacking intervention.
Abstract
The increase in obesity and lipid disorders in industrialized countries may be due to irregular eating patterns. Few studies have investigated the effects of nighttime snacking on energy metabolism. We examined the effects of nighttime snacking for 13 days on energy metabolism. Eleven healthy women (means ± SD; age: 23 ± 1 yr; body mass index: 20.6 ± 2.6 kg/m(2)) participated in this randomized crossover trial for a 13-day intervention period. Subjects consumed a specified snack (192.4 ± 18.3 kcal) either during the daytime (10:00) or the night time (23:00) for 13 days. On day 14, energy metabolism was measured in a respiratory chamber without snack consumption. An oral glucose tolerance test was performed on day 15. Relative to daytime snacking, nighttime snacking significantly decreased fat oxidation (daytime snacking: 52.0 ± 13.6 g/day; nighttime snacking: 45.8 ± 14.0 g/day; P = 0.02) and tended to increase the respiratory quotient (daytime snacking: 0.878 ± 0.022; nighttime snacking: 0.888 ± 0.021; P = 0.09). The frequency of snack intake and energy intake, body weight, and energy expenditure were not affected. Total and low-density lipoprotein (LDL) cholesterol significantly increased after nighttime snacking (152 ± 26 mg/dl and 161 ± 29 mg/dl; P = 0.03 and 76 ± 20 mg/dl and 83 ± 24 mg/dl; P = 0.01, respectively), but glucose and insulin levels after the glucose load were not affected. Nighttime snacking increased total and LDL cholesterol and reduced fat oxidation, suggesting that eating at night changes fat metabolism and increases the risk of obesity.
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Glycemic load effect on fasting and post-prandial serum glucose, insulin, IGF-1 and IGFBP-3 in a randomized, controlled feeding study.
Runchey, SS, Pollak, MN, Valsta, LM, Coronado, GD, Schwarz, Y, Breymeyer, KL, Wang, C, Wang, CY, Lampe, JW, Neuhouser, ML
European journal of clinical nutrition. 2012;66(10):1146-52
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Dietary intervention studies have shown detrimental metabolic effects of high-glycaemic load diets. The glycaemic index (GI) is the numerical classification of a particular food’s blood glucose-raising effect. The aim of this study was to evaluate the effect of a high-glycaemic load diet on circulating levels of insulin-like growth factor-1 (IGF-1) [hormone] and insulin-like growth factor-binding protein 3 (IGFBP-3) [protein] compared to a low-glycaemic load diet. The study is a randomised controlled crossover study which enrolled 84 normal weight and overweight-obese healthy individuals. The study included two 28-day weight-maintaining high- and low-glycaemic load diets. Results indicate that consumption of a low-glycaemic load diet resulted in lower post-prandial [after a meal] insulin and glucose responses and modestly lower fasting IGF-1 and IGF-1/IGFBP-3 concentrations. However, there were no observable effects of glycaemic load on insulin resistance or glucose-adjusted post-prandial insulin responses in these healthy participants. Authors conclude that further intervention studies are required in order to weigh the impact of dietary glycaemic load on risk for chronic disease.
Abstract
BACKGROUND/OBJECTIVES The effect of a low glycemic load (GL) diet on insulin-like growth factor-1 (IGF-1) concentration is still unknown but may contribute to lower chronic disease risk. We aimed to assess the impact of GL on concentrations of IGF-1 and IGF-binding protein-3 (IGFBP-3). SUBJECTS/METHODS We conducted a randomized, controlled crossover feeding trial in 84 overweight obese and normal weight healthy individuals using two 28-day weight-maintaining high- and low-GL diets. Measures were fasting and post-prandial concentrations of insulin, glucose, IGF-1 and IGFBP-3. In all 80 participants completed the study and 20 participants completed post-prandial testing by consuming a test breakfast at the end of each feeding period. We used paired t-tests for diet component and linear mixed models for biomarker analyses. RESULTS The 28-day low-GL diet led to 4% lower fasting concentrations of IGF-1 (10.6 ng/ml, P=0.04) and a 4% lower ratio of IGF-1/IGFBP-3 (0.24, P=0.01) compared with the high-GL diet. The low-GL test breakfast led to 43% and 27% lower mean post-prandial glucose and insulin responses, respectively; mean incremental areas under the curve for glucose and insulin, respectively, were 64.3±21.8 (mmol/l/240 min; P<0.01) and 2253±539 (μU/ml/240 min; P<0.01) lower following the low- compared with the high-GL test meal. There was no effect of GL on mean homeostasis model assessment for insulin resistance or on mean integrated post-prandial concentrations of glucose-adjusted insulin, IGF-1 or IGFBP-3. We did not observe modification of the dietary effect by adiposity. CONCLUSIONS Low-GL diets resulted in 43% and 27% lower post-prandial responses of glucose and insulin, respectively, and modestly lower fasting IGF-1 concentrations. Further intervention studies are needed to weigh the impact of dietary GL on risk for chronic disease.