Sleep Duration Alters Overfeeding-mediated Reduction in Insulin Sensitivity.

CONTEXT: Weight gain and sleep restriction both reduce insulin sensitivity. However, it is not known if sleep duration alters glucose metabolism in response to overfeeding. OBJECTIVE: To examine the effect of sleep duration on overfeeding-mediated alterations in carbohydrate metabolism and insulin sensitivity. METHODS: Retrospective exploratory analysis of a longitudinal overfeeding study in healthy participants (n = 28, age: 26.9 ± 5.5 years, body mass index: 25.74 ± 2.45 kg/m2). After providing baseline study measures, participants were overfed 40% above weight maintenance calorie requirements for 8 weeks. Insulin sensitivity was determined by a 2-step hyperinsulinemic-euglycemic clamp. Baseline habitual sleep duration was estimated by accelerometry, and sleep groups were created based on median sleep duration (5.2 hours/night). RESULTS: Overfeeding led to an average body weight gain of 7.3 ± .4 kg. Habitual sleep duration did not alter overfeeding-mediated body weight gain, fat gain, and fat distribution (all P > .15). Compared to participants with more sleep, fasting insulin (P = .01) and homeostatic model assessment for insulin resistance (P = .02) increased while fasting glucose remained unchanged (P = .68) with overfeeding in participants with shorter sleep duration. Glucose infusion rate during high insulin dose was reduced with overfeeding in participants with short sleep duration but not in participants with more sleep (P < .01). CONCLUSION: Overfeeding mediated weight gain reduced liver, adipose, and whole-body insulin sensitivity prominently in individuals with short sleep duration but not in individuals with longer sleep duration. This suggests that promoting adequate sleep during short periods of overeating may prevent detrimental effects on glucose metabolism.

Effects of metformin on glucose metabolism and mitochondrial function in patients with obstructive sleep apnea: A pilot randomized trial.

Obstructive sleep apnea (OSA) is associated with increased risk for diabetes, and standard treatment with positive airway pressure (PAP) device shows inconsistent effects on glucose metabolism. Metformin is known to treat and prevent diabetes, but its effects on skeletal muscle mitochondrial function are not completely understood. Here, we evaluate the effects of metformin on glucose metabolism and skeletal muscle mitochondrial function in patients with OSA. Sixteen adults with obesity (50.9 ± 6.7 years, BMI: 36.5 ± 2.9 kg/m2 ) and moderate-to-severe OSA were provided with PAP treatment and randomized to 3 months of placebo (n = 8) or metformin (n = 8) treatment in a double-blind parallel-group design. Whole body glucose metabolism was determined by oral glucose tolerance test. A skeletal muscle biopsy was obtained to evaluate mitochondrial respiratory capacity and expression of proteins related to mitochondrial dynamics and energy metabolism. Whole body insulin-sensitivity (Matsuda index) did not change in metformin or placebo treated groups. However, metformin treatment prevented increases in insulin release relative to placebo during follow-up. Insulin area under the curve (AUC) and insulin to glucose AUC ratio increased in placebo but remained unchanged with metformin. Furthermore, metformin treatment improved skeletal muscle mitochondrial respiratory capacity and dynamics relative to placebo. Metformin treatment prevented the decline in whole body glucose homeostasis and skeletal muscle mitochondrial function in patients with moderate to severe OSA. Patients with OSA may benefit from the addition of metformin to prevent diabetes.

Validation of remote child weight and height measurements within a weight management trial.

OBJECTIVE: The aim of this substudy within the Treatment Efforts Addressing Child Weight Management by Unifying Patients, Parents, and Providers (TEAM UP) pragmatic clinical trial was to compare the validity of anthropometric measurements collected remotely versus in person (≤7 days apart) among youth with obesity who were 6 to 15 years of age. METHODS: Child (n = 37) weight and height were measured in person by a trained data assessor. These were compared with measurements taken remotely by the child's parent with live videoconferencing observation by a study data assessor. In-person and remote measurements were compared using Bland-Altman plots, Pearson correlations, and two one-sided paired t tests. A priori bounds of acceptability were set at ±0.68 kg to allow for typical weight fluctuations within the 7-day comparison period. RESULTS: Measurements were highly correlated (height: r = 0.991, p < 0.0001; weight: r = 0.999; p = 0.03). For height, two one-sided t tests for upper, t(36) = 3.95, and lower, t(36) = -2.63, bounds (-1, 1) revealed an overall p = 0.006; absolute error was 3.5 cm. For weight, two one-sided t tests for upper, t(36) = 1.93, and lower, t(36) = -7.91, bounds (-0.68, 0.68) revealed an overall p = 0.03; absolute error was 1.7 kg. CONCLUSIONS: The present findings support the utility and interpretation of remotely assessed weight management outcomes for both research and clinical purposes. These procedures may offer greater accessibility to evidence-based measurement.

Effects of Episodic Food Insecurity on Psychological and Physiological Responses in African American Women With Obesity (RESPONSES): Protocol for a Longitudinal Observational Cohort Study.

BACKGROUND: Food insecurity is a risk factor for multiple chronic diseases, including obesity. Importantly, both food insecurity and obesity are more prevalent in African American women than in other groups. Furthermore, food insecurity is considered a cyclic phenomenon, with episodes of food adequacy (ie, enough food to eat) and food shortage (ie, not enough food to eat). More research is needed to better understand why food insecurity is linked to obesity, including acknowledging the episodic nature of food insecurity as a stressor and identifying underlying mechanisms. OBJECTIVE: The objective of this study is to investigate the episodic nature of food insecurity as a stressor via responses in body weight and psychological and physiological parameters longitudinally and do so in a health-disparate population-African American women. METHODS: We enrolled 60 African American women (food-insecure cohort: n=30, 50%; food-secure cohort: n=30, 50%) aged 18-65 years with obesity (BMI 30-50 kg/m2) to measure (1) daily body weight remotely over 22 weeks and (2) psychological and physiological parameters via clinic assessments at the beginning and end of the 22-week study. Furthermore, we are assessing episodes of food insecurity, stress, hedonic eating, and appetite on a weekly basis. We hypothesize that food-insecure African American women with obesity will demonstrate increased body weight and changes in psychological and physiological end points, whereas food-secure African American women with obesity will not. We are also examining associations between changes in psychological and physiological parameters and changes in body weight and performing a mediation analysis on the psychological parameters assessed at the study midpoint. Psychological questionnaires are used to assess stress; executive function, decision-making, and motivation; and affect and nonhomeostatic eating. Physiological measurements are used to evaluate the levels of cortisol, dehydroepiandrosterone-sulfate (DHEA-S), C-reactive protein, thyroid hormones, blood glucose, glycated hemoglobin, and insulin, as well as allostatic load. RESULTS: This study has completed participant recruitment (n=60). At the time of study enrollment, the mean age of the participants was almost 47 (SD 10.8) years, and they had a mean BMI of 39.6 (SD 5.31) kg/m2. All data are anticipated to be collected by the end of 2023. CONCLUSIONS: We believe that this is the first study to examine changes in body weight and psychological and physiological factors in food-insecure African American women with obesity. This study has significant public health implications because it addresses the cyclic nature of food insecurity to identify underlying mechanisms that can be targeted to mitigate the adverse relationship between food insecurity and obesity and reduce health disparities in minority populations. TRIAL REGISTRATION: ClinicalTrials.gov NCT05076487; https://clinicaltrials.gov/study/NCT05076487. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/52193.