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AbstractObjectiveTo determine the effects of diets varying in carbohydrate to fat ratio on total energy expenditure.DesignRandomized trial.SettingMulticenter collaboration at US two sites, August 2014 to May 2017.Participants164 adults aged 18-65 years with a body mass index of 25 or more.InterventionsAfter 12% (within 2%) weight loss on a run-in diet, participants were randomly assigned to one of three test diets according to carbohydrate content (high, 60%, n=54; moderate, 40%, n=53; or low, 20%, n=57) for 20 weeks. Test diets were controlled for protein and were energy adjusted to maintain weight loss within 2 kg. To test for effect modification predicted by the carbohydrate-insulin model, the sample was divided into thirds of pre-weight loss insulin secretion (insulin concentration 30 minutes after oral glucose).Main outcome measuresThe primary outcome was total energy expenditure, measured with doubly labeled water, by intention-to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate. Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.ResultsTotal energy expenditure differed by diet in the intention-to-treat analysis (n=162, P=0.002), with a linear trend of 52 kcal/d (95% confidence interval 23 to 82) for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ). Change in total energy expenditure was 91 kcal/d (95% confidence interval −29 to 210) greater in participants assigned to the moderate carbohydrate diet and 209 kcal/d (91 to 326) greater in those assigned to the low carbohydrate diet compared with the high carbohydrate diet. In the per protocol analysis (n=120, P<0.001), the respective differences were 131 kcal/d (−6 to 267) and 278 kcal/d (144 to 411). Among participants in the highest third of pre-weight loss insulin secretion, the difference between the low and high carbohydrate diet was 308 kcal/d in the intention-to-treat analysis and 478 kcal/d in the per protocol analysis (P<0.004). Ghrelin was significantly lower in participants assigned to the low carbohydrate diet compared with those assigned to the high carbohydrate diet (both analyses). Leptin was also significantly lower in participants assigned to the low carbohydrate diet (per protocol).ConclusionsConsistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance. This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion.Trial registrationClinicalTrials.gov NCT02068885.

\"The goal of the text is to illustrate the \"integration of nutrition and exercise and its impact on optimal exercise performance and training responsiveness.\" This is the most in depth and detailed sports nutrition book on the market authored by the well-known team of McArdle, Katch and Katch. The challenge of this course is presenting nutrition content/material at the level that is appropriate for those studying exercise science and not nutrition\"--Provided by publisher.

Background/Objectives:The MATADOR (Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound) study examined whether intermittent energy restriction (ER) improved weight loss efficiency compared with continuous ER and, if so, whether intermittent ER attenuated compensatory responses associated with ER.Subjects/Methods:Fifty-one men with obesity were randomised to 16 weeks of either: (1) continuous (CON), or (2) intermittent (INT) ER completed as 8 × 2-week blocks of ER alternating with 7 × 2-week blocks of energy balance (30 weeks total). Forty-seven participants completed a 4-week baseline phase and commenced the intervention (CON: N=23, 39.4±6.8 years, 111.1±9.1 kg, 34.3±3.0 kg m-2 ; INT: N=24, 39.8±9.5 years, 110.2±13.8 kg, 34.1±4.0 kg m-2 ). During ER, energy intake was equivalent to 67% of weight maintenance requirements in both groups. Body weight, fat mass (FM), fat-free mass (FFM) and resting energy expenditure (REE) were measured throughout the study.Results:For the N=19 CON and N=17 INT who completed the intervention per protocol, weight loss was greater for INT (14.1±5.6 vs 9.1±2.9 kg; P<0.001). INT had greater FM loss (12.3±4.8 vs 8.0±4.2 kg; P<0.01), but FFM loss was similar (INT: 1.8±1.6 vs CON: 1.2±2.5 kg; P=0.4). Mean weight change during the 7 × 2-week INT energy balance blocks was minimal (0.0±0.3 kg). While reduction in absolute REE did not differ between groups (INT: -502±481 vs CON: -624±557 kJ d-1 ; P=0.5), after adjusting for changes in body composition, it was significantly lower in INT (INT: -360±502 vs CON: -749±498 kJ d-1 ; P<0.05).Conclusions:Greater weight and fat loss was achieved with intermittent ER. Interrupting ER with energy balance 'rest periods' may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency.

The carbohydrate–insulin model of obesity posits that high-carbohydrate diets lead to excess insulin secretion, thereby promoting fat accumulation and increasing energy intake. Thus, low-carbohydrate diets are predicted to reduce ad libitum energy intake as compared to low-fat, high-carbohydrate diets. To test this hypothesis, 20 adults aged 29.9 ± 1.4 (mean ± s.e.m.) years with body mass index of 27.8 ± 1.3 kg m −2 were admitted as inpatients to the National Institutes of Health Clinical Center and randomized to consume ad libitum either a minimally processed, plant-based, low-fat diet (10.3% fat, 75.2% carbohydrate) with high glycemic load (85 g 1,000 kcal −1 ) or a minimally processed, animal-based, ketogenic, low-carbohydrate diet (75.8% fat, 10.0% carbohydrate) with low glycemic load (6 g 1,000 kcal −1 ) for 2 weeks followed immediately by the alternate diet for 2 weeks. One participant withdrew due to hypoglycemia during the low-carbohydrate diet. The primary outcomes compared mean daily ad libitum energy intake between each 2-week diet period as well as between the final week of each diet. We found that the low-fat diet led to 689 ± 73 kcal d −1 less energy intake than the low-carbohydrate diet over 2 weeks ( P  < 0.0001) and 544 ± 68 kcal d −1 less over the final week ( P  < 0.0001). Therefore, the predictions of the carbohydrate–insulin model were inconsistent with our observations. This study was registered on ClinicalTrials.gov as NCT03878108 . In an inpatient, randomized controlled crossover trial, participants consumed 550–700 kcal day −1 fewer calories when following a plant-based, low-fat diet with a high glycemic load compared with an animal-based, low-carbohydrate diet with a low glycemic load; weight loss was comparable between the two diets and there were no significant differences in hunger or enjoyment of the meals.

To evaluate the feasibility of free-living walking training in type 2 diabetic patients and to investigate the effects of interval-walking training versus continuous-walking training upon physical fitness, body composition, and glycemic control. Subjects with type 2 diabetes were randomized to a control (n = 8), continuous-walking (n = 12), or interval-walking group (n = 12). Training groups were prescribed five sessions per week (60 min/session) and were controlled with an accelerometer and a heart-rate monitor. Continuous walkers performed all training at moderate intensity, whereas interval walkers alternated 3-min repetitions at low and high intensity. Before and after the 4-month intervention, the following variables were measured: VO(2)max, body composition, and glycemic control (fasting glucose, HbA(1c), oral glucose tolerance test, and continuous glucose monitoring [CGM]). Training adherence was high (89 ± 4%), and training energy expenditure and mean intensity were comparable. VO(2)max increased 16.1 ± 3.7% in the interval-walking group (P < 0.05), whereas no changes were observed in the continuous-walking or control group. Body mass and adiposity (fat mass and visceral fat) decreased in the interval-walking group only (P < 0.05). Glycemic control (elevated mean CGM glucose levels and increased fasting insulin) worsened in the control group (P < 0.05), whereas mean (P = 0.05) and maximum (P < 0.05) CGM glucose levels decreased in the interval-walking group. The continuous walkers showed no changes in glycemic control. Free-living walking training is feasible in type 2 diabetic patients. Continuous walking offsets the deterioration in glycemia seen in the control group, and interval walking is superior to energy expenditure-matched continuous walking for improving physical fitness, body composition, and glycemic control.

Background/Objectives: Food-induced thermogenesis is generally reported to be higher in the morning, although contrasting results exist because of differences in experimental settings related to the preceding fasting, exercise, sleeping and dieting. To definitively answer to this issue, we compared the calorimetric and metabolic responses to identical meals consumed at 0800 hours and at 2000 hours by healthy volunteers, after standardized diet, physical activity, duration of fast and resting. Subjects/Methods: Twenty subjects (age range 20–35 years, body mass index=19–26 kg m − 2 ) were enrolled to a randomized cross-over trial. They randomly received the same standard meal in the morning and, 7 days after, in the evening, or vice versa. A 30-min basal calorimetry was performed; a further 60-min calorimetry was done 120-min after the beginning of the meal. Blood samples were drawn every 30-min for 180-min. General linear models, adjusted for period and carry-over, were used to evaluate the ‘morning effect’, that is, the difference of morning delta (after-meal minus fasting values) minus evening delta (after-meal minus fasting values) of the variables. Results: Fasting resting metabolic rate (RMR) did not change from morning to evening; after-meal RMR values were significantly higher after the morning meal (1916; 95% confidence interval (CI)=1792, 2041 vs 1756; 1648, 1863 kcal; P <0.001). RMR was significantly increased after the morning meal (90.5; 95% CI=40.4, 140.6 kcal; P <0.001), whereas differences in areas-under-the-curve for glucose (−1800; −2564,−1036 mg dl −1 × h, P <0.001), log-insulin (−0.19; −0.30,−0.07  μ U ml −1 × h; P =0.001) and fatty free acid concentrations (−16.1;−30.0,−2.09 mmol l −1 × h; P =0.024) were significantly lower. Delayed and larger increases in glucose and insulin concentrations were found after the evening meals. Conclusions: The same meal consumed in the evening determined a lower RMR, and increased glycemic/insulinemic responses, suggesting circadian variations in the energy expenditure and metabolic pattern of healthy individuals. The timing of meals should probably be considered when nutritional recommendations are given.

Background/Objectives: Animal studies and pilot experiments in men indicate that the hypothalamic neuropeptide oxytocin limits food intake, and raise the question of its potential to improve metabolic control in obesity. Subjects/Methods: We compared the effect of central nervous oxytocin administration (24 IU) via the intranasal route on ingestive behaviour and metabolic function in 18 young obese men with the results in a group of 20 normal-weight men. In double-blind, placebo-controlled experiments, ad libitum food intake from a test buffet was examined in fasted subjects 45 min after oxytocin administration, followed by the assessment of postprandial, reward-driven snack intake. Energy expenditure was repeatedly assessed by indirect calorimetry and blood was sampled to determine concentrations of blood glucose and hormones. Results: Oxytocin markedly reduced hunger-driven food intake in the fasted state in obese but not in normal-weight men, and led to a reduction in snack consumption in both groups, whereas energy expenditure remained generally unaffected. Hypothalamic–pituitary–adrenal axis secretion and the postprandial rise in plasma glucose were blunted by oxytocin in both groups. Conclusions: Oxytocin exerts an acutely inhibitory impact on food intake that is enhanced rather than decreased in obese compared with normal-weight men. This pattern puts it in contrast to other metabolically active neuropeptides and bodes well for clinical applications of oxytocin in the treatment of metabolic disorders.