Length of Overnight Fasting and 6-year Weight Change in the Cancer Prevention Study-3.

BACKGROUND: Longer overnight fasting (ONF) is a potential strategy for weight control. Although promising, the evidence from large population-based studies is limited. OBJECTIVES: To examine the association of self-reported ONF duration with 3- and 6-y weight change in the American Cancer Society's Cancer Prevention Study-3 prospective cohort. METHODS: United States adult Cancer Prevention Study-3 participants completed a 24-h validated meal and snack timing and frequency grid (weekday and weekend) in 2015, from which weighted ONF hours were calculated. Participants reported body weight in 2015, 2018, and 2021. Three- and 6-y weight change (kg, and % body weight) were assessed. RESULTS: Among 104,420 mostly female (78.5%) participants aged 52.7 ± 9.5 (standard deviation) y followed for 6 y, a 1-h increase in ONF length was associated with a small but statistically significant reduction in weight gain over 3- and 6-y periods [multivariable-adjusted mean difference in % body weight = -0.02, 95% confidence interval (CI): -0.05, -0.00, P = 0.03 and -0.04, 95% CI: -0.07, -0.01, P < 0.01, respectively]. The mean difference of 6-y % reduction in weight gain was slightly greater among individuals with overweight (-0.05, 95% CI: -0.10, 0.00, P = 0.05) and obesity (-0.06, 95% CI: -0.12, 0.01, P = 0.08) compared with those with healthy body mass index (-0.03, 95% CI:-0.07, 0.01, P = 0.13) or underweight (0.16, 95% CI: -0.04, 0.36, P = 0.13, Pinteraction < 0.0001). Stronger associations were observed among those ≤55 y than 56+ (P < 0.001), and those with higher waist circumference (Pinteraction < 0.0001) but not by sex or earlier/later fasting period. CONCLUSIONS: Longer ONF was associated with slightly lower body weight in adult males and females over 6 y that was stronger among those with overweight or obesity, higher waist circumference, and those aged ≤55 y. The magnitude of weight change, although in the hypothesized direction, suggests that prolonged ONF may have modest impact on weight control over time.

Audit of Preoperative Fasting for Elective General Surgeries in the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria.

BACKGROUND: Despite overwhelming evidence in favour of a relaxed fasting protocol, the traditional practice of keeping patients nil per oral from midnight before the day of surgery for all elective operations still appears to hold sway in many practices. METHODS: A prospective study to evaluate the pattern of preoperative fasting among patients undergoing elective general surgical operations in the Department of Surgery, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria, was conducted between June and December 2020. Data obtained was analysed using the IBM SPSS Statistics for Windows, version 24, and presented as descriptive statistics in the form of frequencies and percentages. RESULTS: The mean prescribed fasting duration was 11.2 ± 2.4 hours. The mean actual fasting duration of 17.6 ± 13.1 hours was significantly longer than the mean prescribed fasting duration (p= <0.001). Eighty-nine percent of patients fasted for >12 hours before their surgical operations. Bowel surgeries had the longest actual fasting duration of 34.9 ± 27.5 hours, while ventral hernia repairs and superficial mass excisions had the shortest duration of 13.5 ± 0.7 hours. Surgeries performed after noon had the longest actual fasting duration compared to those performed before noon (21.5 ± 18.7 hours vs. 15.6 ± 8.6 hours). Ninety percent of respondents reported hunger score of>4 while fasting. CONCLUSION: Preoperative fasting duration in our surgical unit remains long and conventional. The potential implications of this practice on patients' physiological status and surgical outcomes are strong enough to motivate a change.

CONTEXTE: Malgré les preuves accablantes en faveur d'un protocole de jeûne assoupli, la pratique traditionnelle consistant à maintenir les patients à jeun par voie orale à partir de minuit avant le jour de l'intervention chirurgicale pour toutes les opérations non urgentes semble toujours avoir cours dans de nombreux cabinets. MÉTHODES: Une étude prospective visant à évaluer le modèle de jeûne préopératoire chez les patients subissant des opérations chirurgicales générales non urgentes dans le département de chirurgie, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria, a été menée entre juin et décembre 2020. Les données obtenues ont été analysées à l'aide du logiciel IBM SPSS Statistics for Windows, version 24, et présentées sous forme de statistiques descriptives sous forme de fréquences et de pourcentages. RÉSULTATS: La durée moyenne de jeûne prescrite était de 11,2 ± 2,4 heures. La durée moyenne du jeûne effectif de 17,6 ± 13,1 heures était significativement plus longue que la durée moyenne du jeûne prescrit (p= <0,001). Quatre-vingt-neuf pour cent des patients sont restés à jeun pendant plus de 12 heures avant leur intervention chirurgicale. Les opérations de l'intestin ont eu la durée de jeûne réelle la plus longue, soit 34,9 ± 27,5 heures, tandis que les réparations de hernies ventrales et les excisions de masses superficielles ont eu la durée la plus courte, soit 13,5 ± 0,7 heures. Les interventions chirurgicales réalisées après midi ont eu la durée de jeûne réelle la plus longue par rapport à celles réalisées avant midi (21,5 ± 18,7 heures contre 15,6 ± 8,6 heures). Quatre-vingt-dix pour cent des personnes interrogées ont signalé une sensation de faim >4 pendant le jeûne. CONCLUSION: La durée du jeûne préopératoire dans notre unité chirurgicale reste longue et conventionnelle. Les implications potentielles de cette pratique sur l'état physiologique des patients et les résultats chirurgicaux sont suffisamment fortes pour motiver un changement. Mots-clés: American Society of Anaesthesiologists (ASA), Score de faim, Nil Per Oral (NPO), Jeûne de nuit, Jeûne prolongé, Protocole de jeûne traditionnel.

Effects of exercising before breakfast on the health of T2DM patients-A randomized controlled trial.

This is the first study to examine whether training before breakfast in the overnight-fasted state is more effective in improving the health of patients with type 2 diabetes mellitus (T2DM) than after breakfast in the fed state. Thirty T2DM patients (60 ± 8 years, 33.7 ± 4.6 kg/m2 ) were randomly assigned to the F group (training in the overnight-fasted state (n = 15)) and to the C group (training in the fed state (control group, n = 15)). All patients completed an 8-week combined endurance/strength training program. Physical training significantly increased time to physical exhaustion during an endurance test (+10.4%), power output during strength tests (chest presses: +36.7% and seated rows: +37.8%), and fat-free mass (+1.7 kg). Body fat mass (-1.9 kg), glycated hemoglobin (HbA1c) values (absolute change: -0.3%), serum insulin values (-2.5 microU/mL), the homeostatic model assessment for insulin resistance (HOMA-IR) index (-1.1), and circulating triglyceride levels (-31 mg/dL) decreased significantly from pre- to post-training. The training had no effect on body mass index, serum fasting glucose, total cholesterol, low-density lipoprotein/high-density lipoprotein ratio or interleukin (IL)-6, IL-10 and tumor necrosis factor (TNF)α levels. Analyses of variance revealed no time × group interaction for any variable (P > .05). The training was effective in improving the health of T2DM patients. However, the preliminary study's data do not provide any evidence that the nutritional state (overnight-fasted or fed) in regular physical training plays a significant role for training-induced adaptations in T2DM patients. Full trials (using other training protocols as well) should be conducted to gain further knowledge about the relevance of pre-exercise breakfast ingestion.

Effects of overnight fasting on working memory-related brain network: an fMRI study.

Glucose metabolism serves as the central source of energy for the human brain. Little is known about the effects of blood glucose level (BGL) on higher-order cognitive functions within a physiological range (e.g., after overnight fasting). In this randomized, placebo-controlled, double blind study, we assessed the impact of overnight fasting (14 h) on brain activation during a working memory task. We sought to mimic BGLs that occur naturally in healthy humans after overnight fasting. After standardized periods of food restriction, 40 (20 male) healthy participants were randomly assigned to receive either glucagon to balance the BGL or placebo (NaCl). A parametric fMRI paradigm, including 2-back and 0-back tasks, was used. Subclinically low BGL following overnight fasting was found to be linked to reduced involvement of the bilateral dorsal midline thalamus and the bilateral basal ganglia, suggesting high sensitivity of those regions to minimal changes in BGLs. Our results indicate that overnight fasting leads to physiologically low levels of glucose, impacting brain activation during working memory tasks even when there are no differences in cognitive performance.

There is no need for overnight fasting of rats in regulatory toxicology studies.

For many years overnight fasting of rats before the collection of clinical pathology blood samples and necropsy has been a common procedure in toxicological studies for regulatory purposes. The fasting was thought to minimize the intragroup variability for clinical pathology and organ weights. However, depriving rats of food overnight will impact animal welfare by interfering with the general metabolism and may result in physiological and behavioural changes. The effects of overnight fasting in comparison to rats that were not fasted prior to necropsy was investigated in lactating rats based on an evaluation of organ weights, haematological, and clinical biochemical parameters. The results of 92 OECD 422 studies were analysed (i.e., Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test) of which approximately half of the studies incorporated fasting prior to necropsy and the other half did not. Terminal body and organ weights from all 92 studies were evaluated. Clinical pathology was included in 78 of these 92 studies. Decreased glucose levels following fasting had been reported in the literature but were not observed when comparing 39 studies with fasted conditions versus 39 studies with non-fasted conditions. Both literature and the analysed database exhibited a reduction in liver weight, alanine aminotransferase, and alkaline phosphatase levels in overnight fasted groups. These differences between fasted and non-fasted states are considered of little account as study results are always interpreted based on the differences in parameter values between treated animals compared to control animals within a study. Contrarily to previously suggested, intragroup variability was lower in the majority of parameters in non-fasted animals. According to laboratory historical data, clinical pathology and organ weight parameters are found to be very similar in male and female rats, indicating that the results of this study may be extrapolatable to non-lactating female and male rats. Based on these comparisons, it is recommended not to fast rats prior to necropsy but to continue feeding all rats ad libitum, to minimize physiological changes in these animals, to reduce variability, improve animal welfare and thereby improve the scientific value of study results.

The Effects of Overnight Fasting Duration on Glucose and Lipid Metabolism in a Sprague-Dawley Rat Model of Nonalcoholic Steatohepatitis with Advanced Fibrosis.

Nonalcoholic steatohepatitis (NASH) can progress to hepatic fibrosis, and is associated with cardiovascular and liver-related mortality. To understand the pathogenesis of NASH, reliable animal models of the disease are useful. In animal studies, the animals are usually fasted overnight before biospecimens are taken, but little is known about the effects of fasting. Here, we investigated the impact of overnight fasting for approximately 9 to 17 h on glucose and lipid metabolism in a Sprague-Dawley (SD) rat model of diet-induced moderate and advanced NASH in comparison to normal SD rats. Our results revealed that in the moderate NASH model rats, the fasting duration did not affect glucose and lipid metabolism, the histopathological findings, or the hepatic mRNA expression levels of genes related to lipid metabolism, cholesterol metabolism, inflammation, fibrosis, and oxidative stress. In contrast, in the normal rats, significant fasting time-dependent reductions were observed in the epididymal fat pad weight and the hepatic mRNA expression levels of adipose differentiation-related protein and heme oxygenase-1. Moreover, in the advanced NASH model rats, a significant fasting time-dependent reduction and increase were observed in the serum insulin level and mRNA expression level of alpha-smooth muscle actin, respectively. Our present results suggest that the influence of the overnight fasting duration differs among the healthy condition, moderate NASH, and advanced NASH statuses. Further studies are needed in humans to determine the appropriate overnight fasting duration for the accurate evaluation of glucose and lipid metabolism in NASH patients.

Extending the Overnight Fast: Sex Differences in Acute Metabolic Responses to Breakfast.

Fasting for over 24 h is associated with worsening glucose tolerance, but the effect of extending the overnight fast period (a form of time-restricted feeding) on acute metabolic responses and insulin sensitivity is unclear. The aim of this pilot study was to determine the acute impact of an increased fasting period on postprandial glycaemia, insulinemia, and acute insulin sensitivity responses to a standard meal. Twenty-four lean, young, healthy adults (12 males, 12 females) consumed a standard breakfast after an overnight fast of 12, 14, and 16 h. Each fast duration was repeated on three separate occasions (3 × 3) in random order. Postprandial glucose and insulin responses were measured at regular intervals over 2 h and quantified as incremental area under the curve (iAUC). Insulin sensitivity was determined by homeostatic modelling assessment (HOMA). After 2 h, ad libitum food intake at a buffet meal was recorded. In females, but not males, insulin sensitivity improved (HOMA%S +35%, p = 0.016, marginally significant) with longer fast duration (16 h vs. 12 h), but paradoxically, postprandial glycaemia was higher (glucose iAUC +37%, p = 0.002). Overall, males showed no differences in glucose or insulin homeostasis. Both sexes consumed more energy (+28%) at the subsequent meal (16 h vs. 12 h). Delaying the first meal of the day by 4 h by extending the fasting period may have adverse metabolic effects in young, healthy, adult females, but not males.