The thermoneutral zone in women takes an "arctic" shift compared to men.

Conventionally, women are perceived to feel colder than men, but controlled comparisons are sparse. We measured the response of healthy, lean, young women and men to a range of ambient temperatures typical of the daily environment (17 to 31 °C). The Scholander model of thermoregulation defines the lower critical temperature as threshold of the thermoneutral zone, below which additional heat production is required to defend core body temperature. This parameter can be used to characterize the thermoregulatory phenotypes of endotherms on a spectrum from "arctic" to "tropical." We found that women had a cooler lower critical temperature (mean ± SD: 21.9 ± 1.3 °C vs. 22.9 ± 1.2 °C, P = 0.047), resembling an "arctic" shift compared to men. The more arctic profile of women was predominantly driven by higher insulation associated with more body fat compared to men, countering the lower basal metabolic rate associated with their smaller body size, which typically favors a "tropical" shift. We did not detect sex-based differences in secondary measures of thermoregulation including brown adipose tissue glucose uptake, muscle electrical activity, skin temperatures, cold-induced thermogenesis, or self-reported thermal comfort. In conclusion, the principal contributors to individual differences in human thermoregulation are physical attributes, including body size and composition, which may be partly mediated by sex.

Metabolomic Profiling of an Ultraprocessed Dietary Pattern in a Domiciled Randomized Controlled Crossover Feeding Trial.

BACKGROUND: Objective markers of ultraprocessed foods (UPF) may improve the assessment of UPF intake and provide insight into how UPF influences health. OBJECTIVES: To identify metabolites that differed between dietary patterns (DPs) high in or void of UPF according to Nova classification. METHODS: In a randomized, crossover, controlled-feeding trial (clinicaltrials.govNCT03407053), 20 domiciled healthy participants (mean ± standard deviation: age 31 ± 7 y, body mass index [kg/m2] 22 ± 11.6) consumed ad libitum a UPF-DP (80% UPF) and an unprocessed DP (UN-DP; 0% UPF) for 2 wk each. Metabolites were measured using liquid chromatography with tandem mass spectrometry in ethylenediaminetetraacetic acid plasma, collected at week 2 and 24-h, and spot urine, collected at weeks 1 and 2, of each DP. Linear mixed models, adjusted for energy intake, were used to identify metabolites that differed between DPs. RESULTS: After multiple comparisons correction, 257 out of 993 plasma and 606 out of 1279 24-h urine metabolites differed between UPF-DP and UN-DP. Overall, 21 known and 9 unknown metabolites differed between DPs across all time points and biospecimen types. Six metabolites were higher (4-hydroxy-L-glutamic acid, N-acetylaminooctanoic acid, 2-methoxyhydroquinone sulfate, 4-ethylphenylsulfate, 4-vinylphenol sulfate, and acesulfame) and 14 were lower following the UPF-DP; pimelic acid, was lower in plasma but higher in urine following the UPF-DP. CONCLUSIONS: Consuming a DP high in, compared with 1 void of, UPF has a measurable impact on the short-term human metabolome. Observed differential metabolites could serve as candidate biomarkers of UPF intake or metabolic response in larger samples with varying UPF-DPs. This trial was registered at clinicaltrials.gov as NCT03407053 and NCT03878108.

No significant salt or sweet taste preference or sensitivity differences following ad libitum consumption of ultra-processed and unprocessed diets: a randomized controlled pilot study.

Ultra-processed food consumption has increased worldwide, yet little is known about the potential links with taste preference and sensitivity. This exploratory study aimed to (i) compare sweet and salty taste detection thresholds and preferences following consumption of ultra-processed and unprocessed diets, (ii) investigate whether sweet and salty taste sensitivity and preference were associated with taste substrates (i.e. sodium and sugar) and ad libitum nutrient intake, and (iii) examine associations of taste detection thresholds and preferences with blood pressure (BP) and anthropometric measures following consumption of ultra-processed and unprocessed diets. In a randomized crossover study, participants (N = 20) received ultra-processed or unprocessed foods for 2 weeks, followed by the alternate diet. Baseline food intake data were collected prior to admission. Taste detection thresholds and preferences were measured at the end of each diet arm. Taste-substrate/nutrient intake, body mass index (BMI), and body weight (BW) were measured daily. No significant differences were observed in participant salt and sweet detection thresholds or preferences after 2 weeks on ultra-processed or unprocessed diets. There was no significant association between salt and sweet taste detection thresholds, preferences, and nutrient intakes on either diet arm. A positive correlation was observed between salt taste preference and systolic BP (r = 0.59; P = 0.01), BW (r = 0.47, P = 0.04), and BMI (r = 0.50; P = 0.03) following consumption of the ultra-processed diet. Thus, a 2-week consumption of an ultra-processed diet does not appear to acutely impact sweet or salty taste sensitivity or preference. Trial Registration: ClinicalTrials.gov Identifier NCT03407053.

Triglyceride Paradox Is Related to Lipoprotein Size, Visceral Adiposity and Stearoyl-CoA Desaturase Activity in Black Versus White Women.

RATIONALE: In black women, triglycerides are paradoxically normal in the presence of insulin resistance. This relationship may be explained by race-related differences in central adiposity and SCD (stearoyl-CoA desaturase)-1 enzyme activity index. OBJECTIVE: In a cross-sectional study, to compare fasting and postprandial triglyceride-rich lipoprotein particle (TRLP) concentrations and size in black compared with white pre- and postmenopausal women and determine the relationship between TRLP subfractions and whole-body insulin sensitivity, hepatic and visceral fat, and SCD-1 levels. METHODS AND RESULTS: In 122 federally employed women without diabetes mellitus, 73 black (58 African American and 15 African immigrant) and 49 white; age, 44±10 (mean±SD) years; body mass index, 30.0±5.6 kg/m2, we measured lipoprotein subfractions using nuclear magnetic resonance. Hepatic fat was measured by proton magnetic resonance spectroscopy, insulin sensitivity index calculated by minimal modeling from a frequently sampled intravenous glucose test, and red blood cell fatty acid profiles were measured by gas chromatography and were used to estimate SCD-1 indices. Hepatic fat, insulin sensitivity index, and SCD-1 were similar in black women and lower than in whites, regardless of menopausal status. Fasting and postprandial large, medium, and small TRLPs, but not very small TRLPs, were lower in black women. Fasting large, medium, and very small TRLPs negatively correlated with insulin sensitivity index and positively correlated with visceral and hepatic fat and SCD-1 activity in both groups. In multivariate models, visceral fat and SCD-1 were associated with total fasting TRLP concentrations (adjR2, 0.39; P=0.001). Black women had smaller postprandial changes in large (P=0.005) and medium TRLPs (P=0.007). CONCLUSIONS: Lower visceral fat and SCD-1 activity may contribute to the paradoxical association of lower fasting and postprandial TRLP subfractions despite insulin resistance in black compared with white pre- and postmenopausal women. Similar concentrations of very small TRLPs are related to insulin resistance and could be important mediators of cardiometabolic disease risk in women. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01809288.

Effects of interrupting daily sedentary behavior on children's glucose metabolism: A 6-day randomized controlled trial.

BACKGROUND: Metabolic disease risk in youth is influenced by sedentary behaviors. Acute in-lab studies show that, during a single day, interrupting a sedentary period with short bouts of physical activity improves glucometabolic outcomes. OBJECTIVE: To determine if acutely improved glucose metabolism persists after multi-day interruptions of sitting with walking brief bouts. We hypothesized that children who underwent interrupting sitting on multiple days would demonstrate lower insulin area under the curve during an oral glucose tolerance test compared to uninterrupted sitting. METHODS: Healthy, normoglycemic children (N = 109) ages 7-11 years were randomized to one of two conditions: Control (3 h of daily Uninterrupted Sitting) or Interrupted Sitting (3-min of moderate-intensity walking every 30 min for 3 h daily); with dietary intake controlled through provision of foodstuffs for the entire experiment. Participants attended six consecutive daily visits at a research ambulatory unit. The primary outcome was insulin area under the curve during the oral glucose tolerance test on day 6 during interrupted or uninterrupted sitting; secondary outcomes included glucose and c-peptide area under the curve, energy intake at a buffet meal on day 6, and free-living activity. RESULTS: Among 93 children (42 uninterrupted sitting, 51 interrupted sitting), daily interrupted sitting resulted in 21% lower insulin (ß = 0.102 CI:0.032-0.172, p = 0.005) and a 10% lower C-peptide (ß = 0.043, CI:0.001-0.084, p = 0.045) area under the curve. Matsuda and Glucose Effectiveness Indices were also improved (p's < 0.05). There were no group differences in energy intake or expenditure. CONCLUSIONS: Sustained behavioral change by interrupting sedentary behaviors is a promising intervention strategy for improving metabolic risk in children.

The Effects of Interrupting Sitting Time on Affect and State Anxiety in Children of Healthy Weight and Overweight: A Randomized Crossover Trial.

PURPOSE: Sedentary time relates to higher anxiety and more negative affect in children. This study assessed whether interrupting sitting over 3 hours is sufficient to influence state anxiety, positive affect, or negative affect, and tested weight status as a moderator. METHODS: Analyses were the second (preplanned) purpose of a larger study. Children (N = 61; age: mean [SD] = 9.5 [1.3]; 43% healthy weight) completed 2 experimental conditions: continuous sitting for 3 hours and sitting for 3 hours interrupted with walking for 3 minutes in every 30 minutes. State anxiety, positive affect, and negative affect were reported at pretest and posttest. Multilevel models for repeated measures assessed whether experimental condition predicted posttest scores. RESULTS: Experimental condition was unrelated to posttest state anxiety or positive affect. Weight status moderated how experimental condition influenced posttest negative affect (P = .003). Negative affect was lower in the children of healthy weight after interrupted sitting (vs continuous sitting; ß = -0.8; 95% confidence interval, -1.5 to 0.0, P = .05), but it was higher in the children with overweight/obesity after interrupted sitting (vs continuous sitting; ß = 0.6; 95% confidence interval, 0.0 to 1.2, P = .06). CONCLUSIONS: Interrupting sitting acutely reduced negative affect in children of healthy weight, but not in children with overweight. Further research is needed to better understand the potential emotional benefits of sitting interruptions in youth.

The association between alexithymia and eating behavior in children and adolescents.

OBJECTIVE: Alexithymia, or the difficulty identifying or describing one's own emotions, may be a risk factor for dysregulated eating and excess weight gain. However, the relationships between alexithymia and eating behaviors in community samples of non-clinical youth have not been well-characterized. We hypothesized that alexithymia would be positively associated with disordered and disinhibited eating in a community-based sample of boys and girls without an eating disorder. METHOD: Two hundred children (8-17 years old) across the weight spectrum completed an interview to assess loss of control (LOC) eating and eating-related psychopathology, a laboratory test meal designed to induce disinhibited eating, and questionnaires to assess alexithymia, eating in the absence of hunger, and emotional eating. Linear and logistic regressions were conducted to examine the relationship between alexithymia and eating variables, with age, sex, race, and fat mass as covariates. Test meal analyses also adjusted for lean mass. Given the overlap between alexithymia and depression, all models were repeated with depressive symptoms as an additional covariate. RESULTS: Alexithymia was associated with an increased likelihood of reporting LOC eating (p < .05). Moreover, alexithymia was positively associated with disordered eating attitudes, emotional eating, and eating in the absence of hunger (ps < .05). Greater alexithymia was associated with more carbohydrate and less fat intake at the test meal (ps < .05). After adjusting for depressive symptoms, alexithymia remained associated with eating in the absence of hunger and carbohydrate and fat intake (ps < .05). DISCUSSION: In healthy children, alexithymia is associated with some facets of eating behavior and food intake. If supported prospectively, these preliminary findings suggest alexithymia may be a modifiable risk factor to reduce disordered eating and excess weight gain in youth.

Mindfulness and laboratory eating behavior in adolescent girls at risk for type 2 diabetes.

Mindfulness-based intervention has become increasingly popular to address disinhibited eating in obesity and type 2 diabetes (T2D). Theoretically, present-moment attention promotes the ability to recognize and respond to internal hunger cues and to differentiate physiological hunger from other stimuli. Yet, there is limited research describing the relationship of mindfulness with disinhibited eating patterns in adolescents. In this study, we evaluated the relationship of dispositional mindfulness to laboratory eating in 107 adolescent (12-17 years) girls at risk for T2D. Adolescents reported dispositional mindfulness, were evaluated for recent loss-of-control-eating (LOC-eating) by interview, and participated in two successive, standardized laboratory test meals to assess eating when hungry as well as eating in the absence of hunger (EAH). Adolescents rated state appetite throughout the test meal paradigms. In analyses adjusting for body composition and other possible confounds, mindfulness was inversely related to caloric intake during the EAH paradigm. Mindfulness did not relate to energy intake when hungry. Instead, there was a significant interaction of reported LOC-eating by state hunger, such that girls with recent, reported LOC-eating and high state hunger consumed more calories when hungry, regardless of mindfulness. Findings suggest that in girls at risk for T2D, mindfulness may play a role in disinhibited eating. A propensity for LOC-eating may be most salient for overeating in a high hunger state.

A Randomized Controlled Trial to Prevent Depression and Ameliorate Insulin Resistance in Adolescent Girls at Risk for Type 2 Diabetes.

BACKGROUND: Prospective data suggest depressive symptoms worsen insulin resistance and accelerate type 2 diabetes (T2D) onset. PURPOSE: We sought to determine whether reducing depressive symptoms in overweight/obese adolescents at risk for T2D would increase insulin sensitivity and mitigate T2D risk. METHOD: We conducted a parallel-group, randomized controlled trial comparing a 6-week cognitive-behavioral (CB) depression prevention group with a 6-week health education (HE) control group in 119 overweight/obese adolescent girls with mild-to-moderate depressive symptoms (Center for Epidemiological Studies-Depression Scale [CES-D] ≥16) and T2D family history. Primary outcomes were baseline to post-intervention changes in CES-D and whole body insulin sensitivity index (WBISI), derived from 2-h oral glucose tolerance tests. Outcome changes were compared between groups using ANCOVA, adjusting for respective baseline outcome, puberty, race, facilitator, T2D family history degree, baseline age, adiposity, and adiposity change. Multiple imputation was used for missing data. RESULTS: Depressive symptoms decreased (p < 0.001) in CB and HE from baseline to posttreatment, but did not differ between groups (ΔCESD = -12 vs. -11, 95 % CI difference = -4 to +1, p = 0.31). Insulin sensitivity was stable (p > 0.29) in CB and HE (ΔWBISI = 0.1 vs. 0.2, 95 % CI difference = -0.6 to +0.4, p = 0.63). Among all participants, reductions in depressive symptoms were associated with improvements in insulin sensitivity (p = 0.02). CONCLUSIONS: Girls at risk for T2D displayed reduced depressive symptoms following 6 weeks of CB or HE. Decreases in depressive symptoms related to improvements in insulin sensitivity. Longer-term follow-up is needed to determine whether either program causes sustained decreases in depressive symptoms and improvements in insulin sensitivity. TRIAL REGISTRATION NUMBER: The trial was registered with clinicaltrials.gov (NCT01425905).

Modeling glucose and free fatty acid kinetics in glucose and meal tolerance test.

BACKGROUND: Quantitative evaluation of insulin regulation on plasma glucose and free fatty acid (FFA) in response to external glucose challenge is clinically important to assess the development of insulin resistance (World J Diabetes 1:36-47, 2010). Mathematical minimal models (MMs) based on insulin modified frequently-sampled intravenous glucose tolerance tests (IM-FSIGT) are widely applied to ascertain an insulin sensitivity index (IEEE Rev Biomed Eng 2:54-96, 2009). Furthermore, it is important to investigate insulin regulation on glucose and FFA in postprandial state as a normal physiological condition. A simple way to calculate the appearance rate (Ra) of glucose and FFA would be especially helpful to evaluate glucose and FFA kinetics for clinical applications. METHODS: A new MM is developed to simulate the insulin modulation of plasma glucose and FFA, combining IM-FSIGT with a mixed meal tolerance test (MT). A novel simple functional form for the appearance rate (Ra) of glucose or FFA in the MT is developed. Model results are compared with two other models for data obtained from 28 non-diabetic women (13 African American, 15 white). RESULTS: The new functional form for Ra of glucose is an acceptable empirical approximation to the experimental Ra for a subset of individuals. When both glucose and FFA are included in FSIGT and MT, the new model is preferred using the Bayes Information Criterion (BIC). CONCLUSIONS: Model simulations show that the new MM allows consistent application to both IM-FSIGT and MT data, balancing model complexity and data fitting. While the appearance of glucose in the circulation has an important effect on FFA kinetics in MT, the rate of appearance of FFA can be neglected for the time-period modeled.

Randomized double blind clinical trial on the effect of oral α-cyclodextrin on serum lipids.

BACKGROUND: This single center, double-blinded, cross-over, placebo controlled clinical trial investigated the effect of oral α-cyclodextrin (α-CD), a soluble dietary fiber, on blood lipid and lipoprotein levels in healthy human subjects. α-CD, a cyclical polymer containing 6 glucose subunits, is currently sold as an over the counter food supplement and is also a common additive in many foods. α-CD forms a hydrophobic central cavity that binds lipids and has been shown in animal studies and in previous clinical trials to alter plasma lipid levels. METHODS: We screened for healthy subjects, males and females, between ages 18 to 75. Out of total 103 subjects interviewed, 75 subjects completed the study. Qualified individuals in each gender group were randomized into two groups in terms of which treatment arm they received first (placebo vs. α-CD, receiving 6 grams P.O. a day, for 12-14 weeks with a 7 day wash out between arms). The primary outcome variable, plasma total cholesterol, as well as other tests related to lipids and lipoprotein and glucose metabolism, were measured at baseline and at the end of each arm of the study. RESULTS: α-CD was well tolerated; no serious adverse events related to α-CD were observed. Approximately 8 % of the subjects on α-CD complained of minor gastrointestinal symptoms versus 3 % on placebo (p = 0.2). Small-LDL particle number decreased 10 % (p < 0.045) for subjects on α-CD versus placebo. Fasting plasma glucose (1.6 %, p < 0.05) and Insulin resistance index (11 %, p < 0.04) were also decreased when on α-CD versus placebo. CONCLUSION: α-CD treatment appears to be safe and well tolerated in healthy individuals and showed a modest reduction in small LDL particles, and an improvement in glucose related parameters. TRIAL REGISTRATION: NCT01131299.

Neural activation during anticipated peer evaluation and laboratory meal intake in overweight girls with and without loss of control eating.

The interpersonal model of loss of control (LOC) eating proposes that socially distressing situations lead to anxious states that trigger excessive food consumption. Self-reports support these links, but the neurobiological underpinnings of these relationships remain unclear. We therefore examined brain regions associated with anxiety in relation to LOC eating and energy intake in the laboratory. Twenty-two overweight and obese (BMIz: 1.9±0.4) adolescent (15.8±1.6y) girls with LOC eating (LOC+, n=10) and without LOC eating (LOC-, n=12) underwent functional magnetic resonance imaging (fMRI) during a simulated peer interaction chatroom paradigm. Immediately after the fMRI scan, girls consumed lunch ad libitum from a 10,934-kcal laboratory buffet meal with the instruction to "let yourself go and eat as much as you want." Pre-specified hypotheses regarding activation of five regions of interest were tested. Analysis of fMRI data revealed a significant group by peer feedback interaction in the ventromedial prefrontal cortex (vmPFC), such that LOC+ had less activity following peer rejection (vs. acceptance), while LOC- had increased activity (p<.005). Moreover, functional coupling between vmPFC and striatum for peer rejection (vs. acceptance) interacted with LOC status: coupling was positive for LOC+, but negative in LOC- (p<.005). Activity of fusiform face area (FFA) during negative peer feedback from high-value peers also interacted with LOC status (p<.005). A positive association between FFA activation and intake during the meal was observed among only those with LOC eating. In conclusion, overweight and obese girls with LOC eating may be distinguished by a failure to engage regions of prefrontal cortex implicated in emotion regulation in response to social distress. The relationship between FFA activation and food intake supports the notion that heightened sensitivity to incoming interpersonal cues and perturbations in socio-emotional neural circuits may lead to overeating in order to cope with negative affect elicited by social discomfort in susceptible youth.

Mindfulness and eating behavior in adolescent girls at risk for type 2 diabetes.

OBJECTIVE: The purpose of this investigation was to examine the relationship of dispositional mindfulness to binge eating and associated eating attitudes and behaviors among adolescent girls at risk for type 2 diabetes (T2D). METHODS: Participants were 114 overweight or obese adolescents enrolled in a study of girls with a family history of T2D and mild depressive symptoms. Adolescent self-reports of mindfulness, eating in the absence of hunger, and depressive symptoms were collected. An interview was administered to determine presence of binge eating episodes and a behavioral task was used to assess the reinforcing value of food relative to other nonsnack food rewards. Body composition was assessed using dual-energy X-ray absorptiometry. RESULTS: In analyses accounting for race, percent body fat, lean mass, height, age, and depressive symptoms, dispositional mindfulness was associated with a lower odds of binge eating (p = .002). Controlling for the same potential confounds, mindfulness was also inversely associated with eating concern, eating in the absence of hunger in response to fatigue/boredom, and higher food reinforcement relative to physical activity (all p < .05). DISCUSSION: In girls with a family history of T2D, independent of body composition and depressive symptoms, intraindividual differences in mindfulness are related to binge eating and associated attitudes and behaviors that may confer risk for obesity and metabolic problems. Further research is needed to determine the extent to which mindfulness plays a role in the etiology and/or maintenance of disinhibited eating in adolescents at risk for T2D.

Depressed affect and dietary restraint in adolescent boys' and girls' eating in the absence of hunger.

Data suggest that depressed affect and dietary restraint are related to disinhibited eating patterns in children and adults. Yet, experimental research has not determined to what extent depressed affect acutely affects eating in the absence of physiological hunger (EAH) in adolescents. In the current between-subjects experimental study, we measured EAH in 182 adolescent (13-17 y) girls (65%) and boys as ad libitum palatable snack food intake after youth ate to satiety from a buffet meal. Just prior to EAH, participants were randomly assigned to view either a sad or neutral film clip. Dietary restraint was measured with the Eating Disorder Examination. Adolescents who viewed the sad film clip reported small but significant increases in state depressed affect relative to adolescents who viewed the neutral film clip (p < .001). Yet, there was no main effect of film condition on EAH (p = .26). Instead, dietary restraint predicted greater EAH among girls, but not boys (p < .001). These findings provide evidence that adolescent girls' propensity to report restrained eating is associated with their greater disinhibited eating in the laboratory. Additional experimental research, perhaps utilizing a more potent laboratory stressor and manipulating both affective state and dietary restraint, is required to elucidate how state affect may interact with dietary restraint to influence EAH during adolescence.

Depressive symptoms and observed eating in youth.

Depressive symptoms in youth may be a risk factor for obesity, with altered eating behaviors as one possible mechanism. We tested whether depressive symptoms were associated with observed eating patterns expected to promote excessive weight gain in two separate samples. In Study 1, 228 non-treatment-seeking youth, ages 12-17y (15.3±1.4y; 54.7% female), self-reported depressive symptoms using the Beck Depression Inventory. Energy intake was measured as consumption from a 10,934-kcal buffet meal served at 11:00am after an overnight fast. In Study 2, 204 non-treatment-seeking youth, ages 8-17y (13.0±2.8y; 49.5% female), self-reported depressive symptoms using the Children's Depression Inventory. Energy intake was measured as consumption from a 9835-kcal buffet meal served at 2:30pm after a standard breakfast. In Study 1, controlling for body composition and other relevant covariates, depressive symptoms were positively related to total energy intake in girls and boys. In Study 2, adjusting for the same covariates, depressive symptoms among girls only were positively associated with total energy intake. Youth high in depressive symptoms and dietary restraint consumed the most energy from sweets. In both studies, the effects of depressive symptoms on intake were small. Nevertheless, depressive symptoms were associated with significantly greater consumption of total energy and energy from sweet snack foods, which, over time, could be anticipated to promote excess weight gain.

Differential peripheral immune signatures elicited by vegan versus ketogenic diets in humans.

Nutrition has broad impacts on all physiological processes. However, how nutrition affects human immunity remains largely unknown. Here we explored the impact of a dietary intervention on both immunity and the microbiota by performing a post hoc analysis of a clinical trial in which each of the 20 participants sequentially consumed vegan or ketogenic diets for 2 weeks ( NCT03878108 ). Using a multiomics approach including multidimensional flow cytometry, transcriptomic, proteomic, metabolomic and metagenomic datasets, we assessed the impact of each diet, and dietary switch, on host immunity and the microbiota. Our data revealed that overall, a ketogenic diet was associated with a significant upregulation of pathways and enrichment in cells associated with the adaptive immune system. In contrast, a vegan diet had a significant impact on the innate immune system, including upregulation of pathways associated with antiviral immunity. Both diets significantly and differentially impacted the microbiome and host-associated amino acid metabolism, with a strong downregulation of most microbial pathways following ketogenic diet compared with baseline and vegan diet. Despite the diversity of participants, we also observed a tightly connected network between datasets driven by compounds associated with amino acids, lipids and the immune system. Collectively, this work demonstrates that in diverse participants 2 weeks of controlled dietary intervention is sufficient to significantly and divergently impact host immunity, which could have implications for precision nutritional interventions. ClinicalTrials.gov registration: NCT03878108 .

Glycemia and Gluconeogenesis With Metformin and Liraglutide: A Randomized Trial in Youth-onset Type 2 Diabetes.

OBJECTIVE: Elevated rates of gluconeogenesis are an early pathogenic feature of youth-onset type 2 diabetes (Y-T2D), but targeted first-line therapies are suboptimal, especially in African American (AA) youth. We evaluated glucose-lowering mechanisms of metformin and liraglutide by measuring rates of gluconeogenesis and ß-cell function after therapy in AA Y-T2D. METHODS: In this parallel randomized clinical trial, 22 youth with Y-T2D-age 15.3 ± 2.1 years (mean ± SD), 68% female, body mass index (BMI) 40.1 ± 7.9 kg/m2, duration of diagnosis 1.8 ± 1.3 years-were randomized to metformin alone (Met) or metformin + liraglutide (Lira) (Met + Lira) and evaluated before and after 12 weeks. Stable isotope tracers were used to measure gluconeogenesis [2H2O] and glucose production [6,6-2H2]glucose after an overnight fast and during a continuous meal. ß-cell function (sigma) and whole-body insulin sensitivity (mSI) were assessed during a frequently sampled 2-hour oral glucose tolerance test. RESULTS: At baseline, gluconeogenesis, glucose production, and fasting and 2-hour glucose were comparable in both groups, though Met + Lira had higher hemoglobin A1C. Met + Lira had a greater decrease from baseline in fasting glucose (-2.0 ± 1.3 vs -0.6 ± 0.9 mmol/L, P = .008) and a greater increase in sigma (0.72 ± 0.68 vs -0.05 ± 0.71, P = .03). The change in fractional gluconeogenesis was similar between groups (Met + Lira: -0.36 ± 9.4 vs Met: 0.04 ± 12.3%, P = .9), and there were no changes in prandial gluconeogenesis or mSI. Increased glucose clearance in both groups was related to sigma (r = 0.63, P = .003) but not gluconeogenesis or mSI. CONCLUSION: Among Y-T2D, metformin with or without liraglutide improved glycemia but did not suppress high rates of gluconeogenesis. Novel therapies that will enhance ß-cell function and target the elevated rates of gluconeogenesis in Y-T2D are needed.

Deep phenotyping of post-infectious myalgic encephalomyelitis/chronic fatigue syndrome.

Post-infectious myalgic encephalomyelitis/chronic fatigue syndrome (PI-ME/CFS) is a disabling disorder, yet the clinical phenotype is poorly defined, the pathophysiology is unknown, and no disease-modifying treatments are available. We used rigorous criteria to recruit PI-ME/CFS participants with matched controls to conduct deep phenotyping. Among the many physical and cognitive complaints, one defining feature of PI-ME/CFS was an alteration of effort preference, rather than physical or central fatigue, due to dysfunction of integrative brain regions potentially associated with central catechol pathway dysregulation, with consequences on autonomic functioning and physical conditioning. Immune profiling suggested chronic antigenic stimulation with increase in naïve and decrease in switched memory B-cells. Alterations in gene expression profiles of peripheral blood mononuclear cells and metabolic pathways were consistent with cellular phenotypic studies and demonstrated differences according to sex. Together these clinical abnormalities and biomarker differences provide unique insight into the underlying pathophysiology of PI-ME/CFS, which may guide future intervention.

The Complex Effects of Light on Metabolism in Humans.

Light is an essential part of many life forms. The natural light-dark cycle has been the dominant stimulus for circadian rhythms throughout human evolution. Artificial light has restructured human activity and provided opportunities to extend the day without reliance on natural day-night cycles. The increase in light exposure at unwanted times or a reduced dynamic range of light between the daytime and nighttime has introduced negative consequences for human health. Light exposure is closely linked to sleep-wake regulation, activity and eating patterns, body temperature, and energy metabolism. Disruptions to these areas due to light are linked to metabolic abnormalities such as an increased risk of obesity and diabetes. Research has revealed that various properties of light influence metabolism. This review will highlight the complex role of light in human physiology, with a specific emphasis on metabolic regulation from the perspective of four main properties of light (intensity, duration, timing of exposure, and wavelength). We also discuss the potential influence of the key circadian hormone melatonin on sleep and metabolic physiology. We explore the relationship between light and metabolism through circadian physiology in various populations to understand the optimal use of light to mitigate short and long-term health consequences.

Ad libitum meal energy intake is positively influenced by energy density, eating rate and hyper-palatable food across four dietary patterns.

Diets for the prevention and treatment of obesity are often informed by theories about food characteristics believed to support spontaneous reductions in ad libitum energy intake without inducing hunger. Here we estimated how energy density, hyper-palatability, protein content and eating rate affected ad libitum energy intake of 2,733 meals from four dietary patterns. Energy density, eating rate and hyper-palatable foods were consistently positively related to meal energy intake across all diets. Protein content was positively related to meal energy intake during ultraprocessed and unprocessed diets but was not significantly related to energy intake of minimally processed low-fat or low-carbohydrate meals.