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The use of classic nonparametric tests (cNPTs), such as the Kruskal–Wallis and Mann–Whitney U tests, in the presence of unequal variance for between-group comparisons of means and medians may lead to marked increases in the rate of falsely rejecting null hypotheses and decreases in statistical power. Yet, this practice remains prevalent in the scientific literature, including nutrition and obesity literature. Some nutrition and obesity studies use a cNPT in the presence of unequal variance (i.e. heteroscedasticity), sometimes because of the mistaken rationale that the test corrects for heteroscedasticity. Herein, we discuss misconceptions of using cNPTs in the presence of heteroscedasticity. We then discuss assumptions, purposes, and limitations of 3 common tests used to test for mean differences between multiple groups, including 2 parametric tests: Fisher's ANOVA and Welch's ANOVA; and 1 cNPT: the Kruskal–Wallis test. To document the impact of heteroscedasticity on the validity of these tests under conditions similar to those used in nutrition and obesity research, we conducted simple simulations and assessed type I error rates (i.e. false positives, defined as incorrectly rejecting the null hypothesis). We demonstrate that type I error rates for Fisher's ANOVA, which does not account for heteroscedasticity, and Kruskal–Wallis, which tests for differences in distributions rather than means, deviated from the expected significance level. Greater deviation from the expected type I error rate was observed as the heterogeneity increased, especially in the presence of an imbalanced sample size. We provide brief tutorial guidance for authors, editors, and reviewers to identify appropriate statistical tests when test assumptions are violated, with a particular focus on cNPTs. [ABSTRACT FROM AUTHOR]

Background Regression to the mean (RTM) is a statistical phenomenon where initial measurements of a variable in a nonrandom sample at the extreme ends of a distribution tend to be closer to the mean upon a second measurement. Unfortunately, failing to account for the effects of RTM can lead to incorrect conclusions on the observed mean difference between the 2 repeated measurements in a nonrandom sample that is preferentially selected for deviating from the population mean of the measured variable in a particular direction. Study designs that are susceptible to misattributing RTM as intervention effects have been prevalent in nutrition and obesity research. This field often conducts secondary analyses of existing intervention data or evaluates intervention effects in those most at risk (i.e., those with observations at the extreme ends of a distribution). Objectives To provide best practices to avoid unsubstantiated conclusions as a result of ignoring RTM in nutrition and obesity research. Methods We outlined best practices for identifying whether RTM is likely to be leading to biased inferences, using a flowchart that is available as a web-based app at https://dustyturner.shinyapps.io/DecisionTreeMeanRegression/. We also provided multiple methods to quantify the degree of RTM. Results Investigators can adjust analyses to include the RTM effect, thereby plausibly removing its biasing influence on estimating the true intervention effect. Conclusions The identification of RTM and implementation of proper statistical practices will help advance the field by improving scientific rigor and the accuracy of conclusions. This trial was registered at clinicaltrials.gov as NCT00427193. [ABSTRACT FROM AUTHOR]

Background: High added sugar (AS) intake is associated with obesity and poor diet quality. Guidelines recommended limiting AS to 5-10% of total energy intake, but palatability and feasibility of this AS intake level is uncertain.Objective: To compare adolescents' perceptions of hunger, fullness, and palatability in response to a low AS adequate fiber (LASAF; 5% total energy from AS and 13.5 g fiber/1000 kcal) and a high AS low fiber (HASLF; 25% total energy form AS and 8.2 g/1000 kcal) diet.Design: Adolescents (n = 32, age: 15.3 ± 1.6 yrs., BMI percentile: 47 ± 4, 15 male) completed a randomized, crossover, controlled feeding study. Participants consumed calorie-matched LASAF and HASLF diets for 7 days, separated by a 4 week washout. Body weight was monitored daily on each diet. Hunger, fullness, and palatability were assessed via 100 mm visual analogue scales at the end of each feeding period. Differences were assessed with paired sample t-tests. Data are expressed as mean ± SD.Results: Participants remained weight stable, and no difference in weight change between diet conditions was detected (LASAF: -0.06 ± 0.7 vs. HASLF: -0.02 ± 0.6 kg, p = 0.751). Less hunger (LASAF: 24.1 ± 14.6 vs. HASLF: 32.1 ± 17.6 mm, p = 0.024) and greater fullness (LASAF: 70.2 ± 12.3 vs. HASLF: 61.3 ± 18.1 mm, p = 0.006) were reported on the LASAF compared to the HASLF. Participants reported the diets to be equally palatable (LASAF: 39.6 ± 12.9 vs. HASLF: 37.2 ± 17.8 mm, p = 0.440).Conclusions: Adolescents perceive a LASAF diet to be as palatable as a HASLF diet, but more satiating. LASAF diets should be investigated as a strategy for weight control in adolescents. [ABSTRACT FROM AUTHOR]

Objective We tested the hypothesis that skeletal muscle of endurance-trained male runners would exhibit elevated autophagy and mitophagy markers, which would be associated with greater metabolic flexibility following a high-fat meal (HFM). Methods Muscle biopsies were collected to determine differences in autophagy and mitophagy protein markers and metabolic flexibility under fasting conditions and 4 h following a HFM between endurance-trained male runners (n = 10) and sedentary, non-obese controls (n = 9). Results Maximal oxygen consumption (ml·kg·min −1 ) was approximately 50% higher (p < 0.05) in endurance-trained runners compared with sedentary controls (65.8 ± 2.3 and 43.1 ± 3.4, respectively). Autophagy markers were similar between groups. Mitophagy and mitochondrial dynamics protein markers were significantly higher in skeletal muscle of endurance-trained runners compared with sedentary controls in the fasted state, although unaffected by the HFM. Skeletal muscle metabolic flexibility was similar between groups when fasted (p > 0.05), but increased in response to the HFM in endurance-trained athletes only (p < 0.005). Key mitophagy markers, phospho-Pink1 Thr257 and phospho-Parkin S65 (r = 0.64, p < 0.005), and phospo-Parkin Ser65 and phospho-Drp1 Ser616 (r = 0.70, p < 0.05) were correlated only within the endurance-trained group. Autophagy and mitophagy markers were not correlated with metabolic flexibility. Conclusion In summary, mitophagy may be enhanced in endurance-trained runners based on elevated markers of mitophagy and mitochondrial dynamics. The HFM did not alter autophagy or mitophagy in either group. The absence of a relationship between mitophagy markers and metabolic flexibility suggests that mitophagy is not a key determinant of metabolic flexibility in a healthy population, but further investigation is warranted. [ABSTRACT FROM AUTHOR]

Background: Objective indicators of dietary intake (e.g., biomarkers) are needed to overcome the limitations of self-reported dietary intake assessment methods in adolescents. To our knowledge, no controlled feeding studies to date have evaluated the validity of urinary sodium, nitrogen, or sugar excretion as dietary biomarkers in adolescents.Objective: This investigation aimed to evaluate the validity of urinary sodium, nitrogen, and total sugars (TS) excretion as biomarkers for sodium, protein, and added sugars (AS) intake in nonobese adolescents.Methods: In a crossover controlled feeding study design, 33 adolescents [12-18 y of age, 47 ± 25th percentile (mean ± SD) of body mass index (BMI; in kg/m2) for age] consumed 5% AS [low added sugars (LAS)] and 25% AS [high added sugars (HAS)] isocaloric, macronutrient-matched (55% carbohydrate, 30% fat, and 15% protein) diets for 7 d each, in a randomly assigned order, with a 4-wk washout period between diets. On the final 2 d of each diet period, 24-h urine samples were collected. Thirty-two adolescents completed all measurements (97% retention).Results: Urinary sodium was not different from the expected 90% recovery (mean ± SD: 88% ± 18%, P = 0.50). Urinary nitrogen was correlated with protein intake (r = 0.69, P < 0.001), although it was below the 80% expected recovery (62% ± 7%, P < 0.001). Urinary TS values were correlated with AS intake during the HAS diet (r = 0.77, P < 0.001) and had a higher R2 value of 0.28 than did AS intake (R2 = 0.36). TS excretion differed between LAS (0.226 ± 0.09 mg/d) and HAS (0.365 ± 0.16 mg/d) feeding periods (P < 0.001).Conclusions: Urinary sodium appears to be a valid biomarker for sodium intake in nonobese adolescents. Urinary nitrogen is associated with protein intake, but nitrogen excretion rates were less than previously reported for adults, possibly owing to adolescent growth rates. TS excretion reflects AS at 25% AS intake and was responsive to the change in AS intake. Thus, urinary biomarkers are promising objective indicators of dietary intake in adolescents, although larger-scale feeding trials are needed to confirm these findings. This trial was registered at clinicaltrials.gov as NCT02455388. [ABSTRACT FROM AUTHOR]

Background Aerobic exercise interventions have been shown to result in alterations to dietary intake and non-exercise physical activity (PA). To date, the ability for resistance training (RT) to influence other health-related behaviors has not been examined. This study aimed to determine if initiation and maintenance of RT is associated with spontaneous changes in dietary quality and non-RT PA in adults with prediabetes. Methods Overweight/obese adults ( n = 170, BMI = 32.9 ± 3.8 kg·m 2 , age = 59.5 ± 5.5 years, 73% female) with prediabetes were enrolled in the 15-month Resist Diabetes trial. Participants completed a supervised 3-month RT initiation phase followed by a 6-month maintenance phase and a 6-month no-contact phase. Participants were not encouraged to change eating or non-RT PA behaviors. At baseline, and months 3, 9, and 15, three 24-hour diet recalls were collected to evaluate dietary intake and quality, the Aerobics Institute Longitudinal Study Questionnaire was completed to evaluate non-RT PA, and body mass, body composition (DXA), and muscular strength were measured. At months 3, 9, and 15 social cognitive theory (SCT) constructs were assessed with a RT Health Beliefs Questionnaire. Mixed effects models were used to assess changes in dietary intake and non-RT PA over the 15-month study period. Results Energy and carbohydrate intake decreased with RT initiation and maintenance phases (baseline to month 9: β = − 87.9, p = 0.015 and β = − 16.3, p < 0.001, respectively). No change in overall dietary quality (Healthy Eating Index [HEI]-2010 score: β = − 0.13, p = 0.722) occurred, but alterations in HEI-2010 sub-scores were detected. Maintenance of RT was accompanied by an increase in MET-min/week of total non-RT PA (month 3 to month 9: β = 146.2, p = 0.01), which was predicted by increased self-regulation and decreased negative outcome expectancies for RT (β = 83.7, p = 0.014 and β = − 70.0, p = 0.038, respectively). Conclusions Initiation and maintenance of RT may be a gateway behavior leading to improvements in other health-related behaviors. These results provide rationale for single-component lifestyle interventions as an alternative to multi-component interventions, when resources are limited. [ABSTRACT FROM AUTHOR]

Engagement in one type of health behavior change may exert a "spillover" effect resulting in other behavior changes. Few studies have examined dietary intake following prolonged training, and none have evaluated spontaneous dietary changes beyond alterations in energy or macronutrient intake following initiation of strength/resistance training (RT). The purpose of this observational investigation was to determine if spontaneous dietary intake modifications occur in response to initiation of an RT program, among older adults. Previously sedentary adults with prediabetes (n=134, age=59±1 years) were enrolled in a supervised 12-week RT program. Participants were not given dietary advice or encouraged to change eating behaviors. Three non-consecutive 24-hour dietary recalls were collected at baseline and after 12 weeks of RT. Reductions in intake of energy (1914±40kcal vs. 1834±427kcal, p=0.010), carbohydrate (211.6±4.9g vs. 201.7±5.2g, p=0.015), total sugar (87.4±2.7g vs. 81.5±3.1g, p=0.030), glycemic load (113.4±3.0 vs. 108.1±3.2, p=0.031), fruits and vegetables (4.6±0.2 servings vs. 4.1±0.2 servings, p=0.018), and sweets and desserts (1.1±0.07 servings vs. 0.89±0.07 servings, p=0.023) were detected over time. No changes in other dietary intake variables were observed. Mode of exercise and disease state may be important factors in determining whether dietary modifications occur with exercise initiation, among previously sedentary adults. Successful initiation of RT may represent an opportunity for health care professionals to promote beneficial changes in dietary habits, among older adults with prediabetes. [ABSTRACT FROM AUTHOR]

Providing interventions that facilitate improvement of dietary intake and other health behaviors can improve nutrition-related outcomes in adults with overweight or obesity. Medical nutrition therapy (MNT) behavioral interventions require expertise from registered dietitian nutritionists or international equivalents (dietitians), which no other health care provider can provide for adults with obesity. Current evidence supports the role of MNT behavioral interventions for adults with overweight or obesity as an effective treatment option, when appropriate for and desired by the client. This Academy of Nutrition and Dietetics Position Paper describes potential benefits and concerns regarding dietitian-provided MNT behavioral interventions for adults with overweight and obesity and informs dietitians about implications for practice. This Position Paper is supported by a systematic review examining effectiveness of MNT interventions provided by dietitians and by an evidence-based practice guideline. It is the position of the Academy of Nutrition and Dietetics that MNT behavioral interventions for adults (aged 18 years and older) with overweight or obesity should be a treatment option, when appropriate and desired by the client, to improve cardiometabolic, quality of life, and anthropometric outcomes. Dietitians providing MNT recognize the complex contributors to overweight and obesity, and thus individualize interventions, based on a shared decision-making process, and deliver interventions in an inclusive, compassionate, and client-centered manner. Interventions should include collaboration with an interprofessional team when needed. Dietitians strive to increase health equity and reduce health disparities by advocating and providing opportunities for increased access to effective nutrition care services. This position remains in effect until December 31, 2031. [ABSTRACT FROM AUTHOR]

Obesity is associated with a multitude of comorbidities and considerable health care costs. The objective of this review was to examine the efficacy of weight management interventions provided by a registered dietitian or international equivalent (referred to as "dietitian"). This systematic review and meta-analysis of randomized controlled trials (RCTs) examined the effect of weight management interventions provided by a dietitian, compared with usual care or no intervention, on several cardiometabolic outcomes and quality of life in adults with overweight or obesity. MEDLINE, Embase, PsycINFO, Cochrane CENTRAL, Cochrane Database of Systematic Reviews, and CINAHL databases were searched for eligible RCTs published between January 2008 and January 2021 in the English language. Meta-analyses were conducted using a random-effects model, publication bias was assessed using funnel plots and Egger's statistics, and heterogeneity was assessed by interpreting I 2 values. Efficacy of intervention components, such as telehealth or group contacts, were explored in sub-group analyses. Version 2 of the risk-of-bias tool for RCTs was used to assess risk of bias. The Grading of Recommendations Assessment, Development and Evaluation method was used to determine certainty of evidence. This systematic review included 62 RCTs. Compared with control conditions, weight management interventions provided by a dietitian resulted in improved body mass index (mean difference [MD] –1.5; 95% CI –1.74 to –1.26; moderate evidence certainty); percent weight loss (MD –4.01%; 95% CI –5.26% to –2.75%; high evidence certainty); waist circumference (MD –3.45 cm; 95% CI –4.39 to –2.51 cm; high evidence certainty); blood pressure (MD –3.04 mm Hg; 95% CI –5.10 to –0.98 mm Hg and MD –1.99 mm Hg; 95% CI –3.02 to –0.96 mm Hg for systolic blood pressure and diastolic blood pressure, respectively; moderate and low evidence certainty); and quality of life using the 36-Item Short Form Survey (MD 5.84; 95% CI 2.27 to 9.41 and 2.39; 95% CI 1.55 to 3.23 for physical and mental quality of life, respectively; low and moderate evidence certainty). For adults with overweight or obesity, weight management interventions provided by a dietitian are efficacious for improving several examined cardiometabolic outcomes and quality of life. [Display omitted] [ABSTRACT FROM AUTHOR]

Prediabetes is associated with low-grade chronic inflammation that increases the risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). An elevated lipopolysaccharide concentration, associated with dysbiosis of the intestinal microbiota, has been implicated in the development of both T2D and CVD. Selective modulation of the intestinal microbiota with prebiotics reduces intestinal permeability and endotoxin concentrations, inflammation, and metabolic dysfunction in rodents. The effect of prebiotic supplementation on cardio-metabolic function in humans at risk for T2D is not known. The primary aim of this trial is to determine the influence of prebiotic supplementation with inulin on insulin sensitivity and skeletal muscle metabolic flexibility in adults at risk for T2D. We hypothesize that prebiotic supplementation with inulin will improve insulin sensitivity and skeletal muscle metabolic flexibility. We will randomize 48 adults (40–75 yrs) with prediabetes or a score ≥ 5 on the American Diabetes Association (ADA) risk screener to 6 weeks of prebiotic supplementation with inulin (10 g/day) or placebo. Subjects will be provided with all food for the duration of the study, to avoid potential confounding through differences in dietary intake between individuals. Intestinal permeability, serum endotoxin concentrations, insulin sensitivity, skeletal muscle metabolic flexibility, endothelial function, arterial stiffness, and fecal bacterial composition will be measured at baseline and following treatment. The identification of prebiotic supplementation with inulin as an efficacious strategy for reducing cardio-metabolic risk in individuals at risk of T2D could impact clinical practice by informing dietary recommendations and increasing acceptance of prebiotics by the scientific and medical community. [ABSTRACT FROM AUTHOR]

Overweight and obesity affect most adults living in the United States and are causally linked to several adverse health outcomes. Registered dietitian nutritionists or international equivalents (dietitians) collaborate with each client and other health care professionals to meet client-centered goals, informed by the best available evidence, and translated through a lens of clinical expertise and client circumstances and preferences. Since the last iteration of the Academy of Nutrition and Dietetics guideline on adult weight management in 2014, considerable research has been conducted and circumstances confronting dietitians have evolved. Thus, updated guidance is needed. The objective of this evidence-based practice guideline is to provide recommendations for dietitians who deliver medical nutrition therapy behavioral interventions for adults (18 years and older) with overweight and obesity to improve cardiometabolic outcomes, quality of life, and weight outcomes, when appropriate for and desired by the client. Recommendations in this guideline highlight the importance of considering complex contributors to overweight and obesity and individualizing interventions to client-centered goals based on specific needs and preferences and shared decision making. The described recommendations have the potential to increase access to care and decrease costs through utilization of telehealth and group counseling as effective delivery methods, and to address other barriers to overweight and obesity management interventions. It is essential for dietitians to collaborate with clients and interprofessional health care teams to provide high-quality medical nutrition therapy interventions using the nutrition care process to promote attainment of client-centered outcomes for adults with overweight or obesity. [ABSTRACT FROM AUTHOR]

The purpose of the current study was to examine the influence of “time” on isometric elbow flexion torque, body temperature and muscle size without interrupting the sleep wake cycle in college aged males. Two hours following the participants normal wake time, oral temperature was measured, followed by muscle thickness of the upper and lower body using ultrasound, as well as elbow flexor torque via a maximal voluntary contraction (MVC). Measurements were repeated every 2 h for 12 h (Time points 1–7). To examine the repeatability of the rhythm, participants returned and completed the same procedures as before within 14 days of their first circadian visit (Circadian visit 2). There was no time × day interaction for body temperature (p = 0.29), nor were there main effects for time (p = 0.15) or day (p = 0.74). For MVC, there was no time × day interaction (p = 0.93) or main effect for day (p = 0.50), however, there was a main effect for time (p = 0.01). MVC at time points 1 (86.4 ± 6.4 Nm) and 2 (87.1 ± 6.2 Nm) was greater than time points 4 (84.2 ± 6.6 Nm) and 6 (83.4 ± 6.8 Nm, p < 0.05). Additionally, time point 5 MVC was greater than time point 4. For upper body muscle thickness, there was no time × day interaction (p = 0.34), nor was there a main effect for day (p = 0.38), or time (p = 0.06). For lower body muscle thickness, there was no time × day interaction (p = 0.57), nor was there a main effect for day (p = 0.75), or time (p = 0.13). Cosinor analyses revealed no group level rhythms for oral temperature, muscle thickness or strength (p > 0.05), however, there were some individual rhythms noted for muscle thickness and strength. Results suggest that, when accounting for an individuals normal wake time, circadian rhythms of strength, temperature and muscle thickness are not apparent in most individuals. [ABSTRACT FROM AUTHOR]

• Sex-based differences in ratings of hunger following acute exercise (EX) exist. • Hormonal indices of appetite do not differ between men and women following acute EX. • Relative energy intake following EX does not differ between men and women. • The relationship between hunger and energy intake in women may be dysregulated. • Acute EX may increase perceived hunger in women and decrease perceived hunger in men. To compare energy intake (EI) and appetite regulation responses between men and women following acute bouts of aerobic (AEx), resistance exercise (REx), and a sedentary control (CON). Men and women (n = 24; 50% male) with overweight/obesity, matched on age (32.3 ± 2 vs. 36.8 ± 2 yrs, p = 0.14) and BMI (28.1 ± 1.2 vs 29.0 ± 1.5 kg/m2, p = 0.64) completed 3 conditions: 1) AEx (65–70% of age-predicted maximum heart rate for 45 min); 2) REx (1-set to failure on 12 exercises); and 3) CON. Each condition was initiated in the post-prandial state (35 min following consumption of a standardized breakfast). Appetite (visual analog scale for hunger, satiety, and prospective food consumption [PFC]) and hormones (ghrelin, PYY, and GLP-1) were measured in the fasted state and every 30 min post-prandially for 3 h. Post-exercise ad libitum EI at the lunch meal was also measured. Men reported higher levels of hunger compared to women across all study conditions (AEx: Men: 7815.00 ± 368.3; Women: 5428.50 ± 440.0 mm x 180 min; p = 0.025; REx: Men: 7110.00 ± 548.4; Women: 6086.25 ± 482.9 mm x 180 min; p = 0.427; CON: Men: 8315.00 ± 429.8; Women: 5311.25 ± 543.1 mm x 180 min; p = 0.021) and consumed a greater absolute caloric load than women at the ad libitum lunch meal (AEx: Men: 1021.6 ± 105.4; Women: 851.7 ± 70.5 kcals; p = 0.20; REx: Men: 1114.7 ± 104.0; Women: 867.7 ± 76.4 kcals; p = 0.07; CON: Men: 1087.0 ± 98.8; Women: 800.5 ± 102.3 kcals; p = 0.06). However, when adjusted for relative energy needs, there was no difference in relative ad libitum EI observed between men and women. No differences in Area Under the Curve for Satiety, PFC, ghrelin, PYY, and GLP-1 were noted between men and women following acute exercise (all p > 0.05). These data suggest that women report lower ratings of appetite following an acute bout of exercise or sedentary time when compared to men, yet have similar relative EI. Future work is needed to examine whether sex-based differences in appetite regulation and EI are present with chronic exercise of differing modalities. [ABSTRACT FROM AUTHOR]