Energy Expenditure In Individuals Research Articles

Pilot Testing to Examine Energy Expenditure Before Reported Fatigue in Individuals With Barth Syndrome

Abstract Date Presented 03/23/24 This study used a phone app to capture fatigue and an activity tracker to assess energy expenditure in individuals with and without Barth syndrome (BTHS). We found that the BTHS group reported fatigue after expending less energy compared to controls. Primary Author and Speaker: Marina Nguyen Additional Authors and Speakers: Alyssa Tsui, Virginia W. Chu, Stacey Reynolds Contributing Authors: Sanamtha Payne, Hannah Ikenberry, Mackenzie Hunter

Effects of 1,144 km of road cycling performed in 7 days: a cardiometabolic imaging study.

This cardiometabolic imaging study was designed to document the adaptation of middle-aged recreational cyclists to a large exercise prescription not aiming at weight loss. Eleven middle-aged recreational male cyclists traveled 1,144 km over seven consecutive days. A comprehensive cardiometabolic profile including visceral and ectopic adiposity assessed by magnetic resonance imaging was obtained at baseline and following the exercise week. Cardiorespiratory fitness (CRF) was measured using maximal cardiopulmonary exercise testing. During the week, heart rate was monitored to calculate individual energy expenditure. Baseline characteristics of cyclists were compared with 86 healthy males in the same age range. Cyclists presented higher baseline CRF (+9.2 mL/kg/min, P < 0.0001) and lower subcutaneous (-56.2 mL, P < 0.05) and liver (-3.3%, P < 0.05) fat compared with the reference group. Despite the large energy expenditure during the cycling week, the increase in energy intake limited decreases in body weight (-0.8 ± 0.9 kg, P < 0.05) and body mass index (-0.3 ± 0.3 kg/m2, P < 0.05). Loss of fat mass (-1.5 ± 1.0 kg, P < 0.001) and a trend toward an increased lean mass (+0.8 ± 1.2 kg, P < 0.07) were observed. Visceral adiposity (-14.1 ± 14.2 mL, P < 0.01) and waist circumference (-3.2 ± 1.7 cm, P < 0.0001) decreased, whereas subcutaneous (-2.7 ± 5.1 mL, NS), liver (-0.5 ± 0.9%, NS), and cardiac (-0.3 ± 2.3 mL, NS) fat remained unchanged. This cardiometabolic imaging study documents middle-aged recreational cyclists' subcutaneous and visceral adiposity as well as cardiac and liver fat responses to a large volume of endurance exercise despite an increase in energy intake aimed at limiting weight loss.NEW & NOTEWORTHY Even when being accompanied by a substantial increase in energy intake to compensate energy expenditure and limit weight loss, a large volume of endurance exercise performed within a short period of time is associated with a significant reduction in visceral adiposity. High cardiorespiratory fitness is associated with low levels of liver fat in middle-aged males.

Methods of Determining Energy Expenditure in Individuals with Prader-Willi Syndrome: A Systematic Literature Review.

Prader-Willi syndrome (PWS) is a rare disorder characterised by varying nutritional phases that occur throughout the lifespan, ranging from failure to thrive to hyperphagia. If uncontrolled, the imbalance between energy intake and expenditure results in obesity development and increased morbidity and mortality risk. Although measures of energy requirements for accurate nutrition assessment are vital, the evidence appears sparse and heterogeneous; hence, the aim of this review was to examine the available literature on energy expenditure predicted or measured using various methods in individuals with PWS. Studies were sought that presented methods and results on resting energy expenditure or basal metabolic rate. A narrative synthesis was completed to present the study characteristics and results. Methods of determining energy requirements included predictive equations and indirect calorimetry. Differences amongst ages, growth hormone therapy, fasting status, and measures in which results were presented were limitations to appropriately summarising and identifying trends in energy expenditure. Indirect calorimetry was identified as the most accurate method; however, it is not widely available in all settings. Further research is encouraged to support the development of valid and reliable predictive equations that will better inform and improve the efficiency of clinical practice in supporting people with PWS.

Prediction of Resting Energy Expenditure in Individuals With Obstructive Sleep Apnea Using Machine Learning

Prediction of Resting Energy Expenditure in Individuals With Obstructive Sleep Apnea Using Machine Learning

Effects of 2 months of methylphenidate on energy expenditure in individuals with obesity: A randomized, double-blind, placebo-controlled pilot study.

Methylphenidate (MPH) has been previously shown to increase resting energy expenditure (REE) in individuals of normal weight; however, the effects on individuals living with obesity are currently unknown. Ten individuals living with obesity were randomly assigned to undergo 60 days of MPH administration with a daily dose of 0.5 mg/kg body weight or a placebo control. REE was measured before and after the 60-day intervention. There was a trend toward significance for group × time interaction on REE (p = 0.082) with a large effect size (η2 = 0.331), with MPH administration increasing REE compared to a decrease in placebo control. Preliminary findings from this pilot study show that MPH has the potential to counter the adaptive thermogenic process commonly seen in weight loss. This is a unique finding among pharmacotherapies, as no approved obesity drugs measurably impact REE.

Butein derivatives prevent obesity and improve insulin resistance through the induction of energy expenditure in high-fat diet-fed obese mice

Obesity is a global public health problem and is related with fatal diseases such as cancer and cardiovascular and metabolic diseases. Medical and lifestyle-related strategies to combat obesity have their limitations. White adipose tissue (WAT) browning is a promising strategy for increasing energy expenditure in individuals with obesity. Uncoupling protein 1 (UCP1) drives WAT browning. We previously screened natural products that enable induction of Ucp1 and demonstrated that these natural products induced WAT browning and increased energy expenditure in mice with diet-induced obesity. In this study, we aimed to extensively optimise the structure of compound 1, previously shown to promote WAT browning. Compound 3 s exhibited a significantly higher ability to induce Ucp1 in white and brown adipocytes than did compound 1. A daily injection of compound 3 s at 5 mg/kg prevented weight gain by 13.6 % in high-fat diet–fed mice without any toxicological observation. In addition, compound 3 s significantly improved glucose homeostasis, decreased serum triacylglycerol levels, and reduced total cholesterol and LDL cholesterol levels, without altering dietary intake or physical activity. Pharmaceutical properties such as solubility, lipophilicity, and membrane permeability as well as metabolic stability, half-life (T1/2), and blood exposure ratio of i.p to i.v were significantly improved in compound 3 s when compared with those in compound 1. Regarding the mode of action of WAT browning, the induction of Ucp1 and Prdm4 by compounds 1 and 3 s was dependent on Akt1 in mouse embryonic fibroblasts. Therefore, this study suggests the potential of compound 3 s as a therapeutic agent for individuals with obesity and related metabolic diseases, which acts through the induction of WAT browning as well as brown adipose tissue activation.

Comparison of energy expenditure of individuals with Duchenne muscular dystrophy in the sitting posture on the ground and in water

Duchenne Muscular Dystrophy (DMD) is one of the most frequent childhood dystrophies, affecting cardiopulmonary functions and walking ability. One of the main symptoms is fatigue, which is caused by altered muscle metabolism related to energy expenditure (EE). Aquatic physiotherapy is a therapeutic modality that facilitates the maintenance of this posture because of immersion on the body. This cross-sectional observational study aimed to compare the EE on the ground and water of individuals with DMD through oxygen consumption in the maintenance of sitting posture. The individuals were in a sitting position on the ground and in the water for 20 min for the assessments. The variables peripheral oxygen saturation, heart rate, maximum expiratory pressure, maximum inspiratory pressure, forced vital capacity, respiratory quotient (RQ), and oxygen consumption per kilogram of body weight (VO2 /kg) were compared, adopting a significance of 5 %. No difference was found between medians and quartiles of RQ when comparing the two environments. The same was observed for VO2 /Kg values on the ground and in water. The data from this study demonstrate that the EE of individuals with DMD did not change when maintaining a sitting posture on the ground and in water.

Research on real-time data analysis system of sports training based on reconfigurable data mining technology

Abstract This paper utilizes smart wearable devices to quickly capture, record, and store performance information (calorie consumption assessment, pedometer, and heart rate monitoring), location information, and biochemical data of sports training populations through the sensory layer. Based on the reconfigurable data mining-related technology, combined with the data and test scores of the sports training population, data mining analysis is carried out to form valuable physiological, physical, and other characteristic information, which provides a scientific and referable strategy for sports training, thus also achieving the purpose of improving the training effect of athletes. The results show that, from the visualization and analysis results of the decision tree model for boys and girls, the girls’ long-distance running event (800 m) and boys’ pull-ups are located in the root node of the decision tree, which has the most significant effect on the performance level. Consequently, sports training programs were created that were more logically based on the distinction between male and female students. In individual exercise energy expenditure, by 420s, the limiting energy expenditure rate of 5.6 kcal/30s exceeded that of the athletes. Moreover, with time, energy expenditure continues to decline. The accuracy of this test can be 90%.

Energy Expenditure And Energy Availability In Active Individuals With Physical Disabilities

Energy Expenditure And Energy Availability In Active Individuals With Physical Disabilities

Adequacy of the “pocket formulas” for measuring total energy expenditure in healthy women compared with the new DRI equation: A doubly labeled water study

Objectives“Pocket formulas” are practical alternatives for calculating an individual's total energy expenditure (TEE). Typically, more sophisticated predictive equations are used, such as the new equations proposed in the Dietary Reference Intakes (DRI). Nevertheless, these new equations necessitate estimating physical activity levels (PALs). The aim of this study was to compare the use of pocket formulas (kcal/kg of body weight) with the new predictive equations for energy expenditure proposed by the DRI (2023) in healthy women and with the doubly labeled water (DLW) method to predict TEE. MethodsThe TEEs of healthy adult women were measured by DLW and calculated using the pocket formulas (× 20, × 25, × 30, and × 35 kcal/kg of body weight) and the new DRI equation. PALs by triaxial accelerometers were also collected. ResultsThe study included 55 women. For the entire sample, the × 30 pocket formula had the lowest bias (–6%; limits of agreement [LOAs]: –39.8; 27.5; root mean square error: 373.4) and the highest precision (42%). The pocket formulas showed reasonable agreement in the different body mass index categories compared with the results found by the 2023 DRI proposal. For individuals with normal weight, the agreement was × 35 kcal/kg: bias (%) = –4.8; LoA = –41.5; 31.8, with overweight, it was × 30 kcal/kg: bias (%) = –2.2; LoA = –25.1; 20.6, and with obesity, it was × 30 kcal/kg: bias (%) = 4.2; LoA = –21.1; 29.4. ConclusionPocket formulas provide a reasonable agreement with TEE in healthy, sedentary, or low-active adult women, which may be a more simplistic strategy when there is no PAL data for calculating the DRI equations.

Influence of behavioural and morphological group composition on pigeon flocking dynamics.

Animals rely on movement to explore and exploit resources in their environment. While movement can provide energetic benefits, it also comes with energetic costs. This study examines how group phenotypic composition individual speed and energy expenditure during group travel in homing pigeons. We manipulated the composition of pigeon groups based on body mass and leadership rank. Our findings indicate that groups of leader phenotypes show faster speeds and greater cohesion than follower phenotype groups. Additionally, we show that groups of homogenous mass composition, whether all heavy or all light, were faster and expended less energy over the course of a whole flight than flocks composed of a mixture of heavy and light individuals. We highlight the importance of considering individual-level variation in social-level studies, and the interaction between individual and group-level traits in governing speed and the cost of travel.

Machine learning models using non-linear techniques improve the prediction of resting energy expenditure in individuals receiving hemodialysis

Purpose Approximately 700,000 people in the USA have chronic kidney disease requiring dialysis. Protein-energy wasting (PEW), a condition of advanced catabolism, contributes to three-year survival rates of 50%. PEW occurs at all levels of Body Mass Index (BMI) but is devastating for those people at the extremes. Treatment for PEW depends on an accurate understanding of energy expenditure. Previous research established that current methods of identifying PEW and assessing adequate treatments are imprecise. This includes disease-specific equations for estimated resting energy expenditure (eREE). In this study, we applied machine learning (ML) modelling techniques to a clinical database of dialysis patients. We assessed the precision of the ML algorithms relative to the best-performing traditional equation, the MHDE. Methods This was a secondary analysis of the Rutgers Nutrition and Kidney Database. To build the ML models we divided the population into test and validation sets. Eleven ML models were run and optimized, with the best three selected by the lowest root mean squared error (RMSE) from measured REE. Values for eREE were generated for each ML model and for the MHDE. We compared precision using Bland-Altman plots. Results Individuals were 41.4% female and 82.0% African American. The mean age was 56.4 ± 11.1 years, and the median BMI was 28.8 (IQR = 24.8 − 34.0) kg/m2. The best ML models were SVR, Linear Regression and Elastic net with RMSE of 103.6 kcal, 119.0 kcal and 121.1 kcal respectively. The SVR demonstrated the greatest precision, with 91.2% of values falling within acceptable limits. This compared to 47.1% for the MHDE. The models using non-linear techniques were precise across extremes of BMI. Conclusion ML improves precision in calculating eREE for dialysis patients, including those most vulnerable for PEW. Further development for clinical use is a priority.

Accuracy of equations for estimating resting energy expenditure in children and adolescents living with phenylketonuria.

Measuring resting energy expenditure (REE) in individuals living with phenylketonuria (PKU) using indirect calorimetry (IC) is unusual in healthcare facilities because it requires specific protocols and expensive equipment. Considering that determining REE is crucial for devising nutritional strategies for the management of PKU, the aim of this study was to identify the predictive equations that provide the best estimates of REE in children and adolescents living with PKU and to propose a predictive equation for determining REE in this population. An REE concordance study was conducted with children and adolescents living with PKU. Anthropometric and body composition assessments using bioimpedance and REE assessment using IC were performed. The results were compared to 29 predictive equations. Fifty-four children and adolescents were evaluated. The REE obtained using IC differed from all estimated REE, except Henry's equation for male children (p = 0.058). Only this equation showed good agreement (0.900) with IC. Eight variables were associated with the REE obtained using IC with emphasis on fat-free mass (kg) (r = 0.786), weight (r = 0.775), height (r = 0.759) and blood phenylalanine (r = 0.503). With these variables, three REE equations were suggested, with R2 = 0.660, 0.635 and 0.618, respectively, and the third equation, which involves weight and height, showed adequate sample size for a statistical power of 0.942. Most equations, not specific for individuals living with PKU, overestimate the REE of this population. We propose a predictive equation for assessing REE for children and adolescents living with PKU to be used in settings where IC is not available.

The Influence of Energy Balance and Availability on Resting Metabolic Rate: Implications for Assessment and Future Research Directions.

Resting metabolic rate (RMR) is a significant contributor to an individual's total energy expenditure. As such, RMR plays an important role in body weight regulation across populations ranging from inactive individuals to athletes. In addition, RMR may also be used to screen for low energy availability and energy deficiency in athletes, and thus may be useful in identifying individuals at risk for the deleterious consequences of chronic energy deficiency. Given its importance in both clinical and research settings within the fields of exercise physiology, dietetics, and sports medicine, the valid assessment of RMR is critical. However, factors including varying states of energy balance (both short- and long-term energy deficit or surplus), energy availability, and prior food intake or exercise may influence resulting RMR measures, potentially introducing error into observed values. The purpose of this review is to summarize the relationships between short- and long-term changes in energetic status and resulting RMR measures, consider these findings in the context of relevant recommendations for RMR assessment, and provide suggestions for future research.

Differences in Muscle Demand and Joint Contact Forces Between Running and Skipping

Skipping has been proposed as a viable cross-training exercise to running due to its lower knee contact forces and higher whole-body energy expenditure. However, how individual muscle forces, energy expenditure, and joint loading are affected by differences in running and skipping mechanics remains unclear. The purpose of this study was to compare individual muscle forces, energy expenditure, and lower extremity joint contact forces between running and skipping using musculoskeletal modeling and simulations of young adults (n = 5) performing running and skipping at 2.5m·s-1 on an instrumented treadmill. In agreement with previous work, running had greater knee and patella contact forces than skipping which was accompanied by greater knee extensor energetic demand. Conversely, skipping had greater ankle contact forces and required greater energetic demand from the uniarticular ankle plantarflexors. There were no differences in hip contact forces between gaits. These findings further support skipping as a viable alternative to running if the primary goal is to reduce joint loading at the commonly injured patellofemoral joint. However, for those with ankle injuries, skipping may not be a viable alternative due to the increased ankle loads. These findings may help clinicians prescribe activities most appropriate for a patient's individual training or rehabilitation goals.

Plasma Metabolomic Profiles Are Imbalanced in Adults Thalassemia Patients with Malnutrition and That Imbalance Is Alleviated By Oral Nutritional Supplements: A Prospective Randomized Controlled Trial

Background: Malnutrition is a common condition observed in children with thalassemia. However, the prevalence of malnutrition, alterations of plasma metabolomes, and the impact of nutritional supplements in adults with thalassemia were still unclear. Objectives: To evaluate the prevalence of malnutrition and plasma metabolomic profiles of adult thalassemia when compared with healthy control, as well as to evaluate the effects of oral nutritional supplements (ONS) on nutritional status and metabolomic profiles in those thalassemia patients with malnutrition Methods: Adult thalassemia (n=100) and healthy control (n=20) aged ≥ 18 years old were enrolled in the present study. This study was divided into 2 phases. Phase I of the study: All participants were assessed nutritional status by nutrition assessment 2013 (NT-2013), serum biomarkers (albumin, transferrin), and anthropometry. Plasma metabolomes including amino acids, long-chain free fatty acids, acylcarnitines (C0-18), and Krebs cycle metabolites were measured by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS). All outcomes were compared among 3 groups including thalassemia with malnutrition, thalassemia without malnutrition, and healthy control. Phase II of the study, thalassemia patients with malnutrition, defined as NT-2013 score of 5 or more, were randomized into two subgroups. Each subgroup received either ONS or nutritional advice by a nutritionist for 3 months. ONS consisted of oral complete formula (Blendera-MF®) and/or whey protein based on the assessment by food questionnaire to achieve the target of individual total daily energy expenditure (Harris-Benedict equation multiplied with activity factor) and total protein of 1.3 g/kg/day. NT-2013, anthropometric parameters, serum biomarkers, and plasma metabolomes were re-evaluated after 12 weeks in each subgroup. ONS adherence was assessed every 2 weeks during the study period. Those with less than 80% ONS adherence were excluded from the final analysis. Results: A total of 100 patients were enrolled with a mean age of 34.9 years (range 18-60). Of which, 65.3% were females and 58.1% were transfusion-dependent thalassemia (TDT). The prevalence of malnutrition was 20% (15% mild, 85% moderate degree). Malnutrition was more common in TDT than non-TDT (30.9% vs 6.7%, p=0.003). Twenty age, sex, and body mass index-matched healthy controls were also enrolled. Regarding plasma amino acids, baseline alanine, proline, and tyrosine were significantly increased while arginine was significantly decreased in malnourished patients. Fatty acid-derived acylcarnitines (C12-18) were significantly increased in malnourished patients compared to the control group. Long-chain free fatty acids were not different between groups. Considering Krebs cycle, citrate was significantly decreased, but malate was significantly increased in malnourished patients compared to the control group (Table 1). Three participants had less than 80% ONS adherence. After 12 weeks, the mean NT-2013 score in overall malnourished patients significantly improved, when compared to their baseline (6.0±1.1 to 5.2±1.5, p=0.029). However, there was a trend of more improvement in ONS group than nutritional advice group (6.1±1.0 to 5.0±1.5, p=0.084 vs. 5.9±1.2 to 5.5±1.5, p=0.223). Fatty acid-derived acylcarnitines (C8-18) and malate were significantly decreased after ONS (Table 2). Anthropometric parameters, serum biomarkers, long-chain free fatty acids, and amino acids were not changed. Conclusions: The prevalence of malnutrition in adult thalassemia was 20%. Plasma metabolomic profiles suggested that the malnourished thalassemia had imbalanced protein turnover and incomplete fatty acid oxidation, resulting in the disruption of Krebs' cycle. Among thalassemia patients with malnutrition, both ONS and nutritional advice led to improve nutritional status. ONS for 12 weeks also promoted more complete fatty acid oxidation in malnourished thalassemia. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Bias and Motivation of Energy Monitoring during Exercise under Scientometric Perspective

The thermodynamics is of great value for better practical applications of Internet of Things (IoT). With the development of IoT, Wearable Energy Harvester can provide more abundant measurement methods for human engineering and human heat. However, how close the relationship is between traditional individual thermal measurement and emerging technologies remains a topic that has not been paid attention to. Therefore, this paper first sorts and summarizes the literature of human calorimetry and then shows the cross field of Wearable Energy Harvester and traditional research using graph theory. Specifically, this paper presents the evolution of the research field in the form of dual-map overlays by characterizing the network structure and measuring the structural transformation of the knowledge network. With Web of Science as the data source and CiteSpace 5.0 software as the tool to make a knowledge graph for quantitative statistics, it is found that the research hotspot of individual energy expenditure is in the physiological field. The starting point of individual thermal energy monitoring technology represented by Wearable Energy Harvester is to aid with human health. However, as time progresses, although the development of this field still focuses on the fields of chemical industry and materials, it has gradually become closely related to multiple disciplines such as the monitoring of thermal energy during high-intensity sports training.

Comparison of Measured Versus Predicted Resting Energy Expenditure in Individuals With Excess Body Weight

ObjectivesAssessing resting energy expenditure (REE) is important for determining energy requirements. Indirect calorimetry is usually not available in clinical settings and for this reason, predictive equations for estimating REE have been developed. Body composition influences REE; therefore, body compartments such fat-free mass (FFM) and fat mass (FM) should be considered in predictive equations. The aim of this study was to compare REE measured by indirect calorimetry with REE estimated from seven predictive equations that consider body composition in individuals with excess body weight. MethodsThis was a preliminary baseline data from a randomized controlled trial. REE was measured in adults with overweight and obesity using a whole-body calorimetry unit. Dual-energy X-ray absorptiometry was used to assess FM and FFM. Measured REE (mREE) was compared to seven predictive equations that incorporated FFM and FM. Age and body composition were compared between sexes using independent-samples t-test. A paired-samples t-test was used to compare mREE versus predicted REE (pREE). Bias and limits of agreement (LOA) were accessed by Bland-Altman analysis. pREE values between 95% and 105% of mREE were considered accurate. ResultsTwenty-one adults (n = 15 females, age: 27 ± 7 years, BMI: 29.0 ± 2.9 kg/m2, mREE: 1769 ± 342 kcal/day) were assessed. Age, FM, and FFM were not different between sexes (P > 0.05). The Muller et al., 2001 (Praxis 90: 1955–1963) and Horie et al., 2007 (Obesity 19: 1090–1094) equations were considered accurate and showed small bias, but high standard deviation (33.5 ± 178.2 and –51.4 ± 208.6 kcal/day) and wide LOAs (-316 to 383 and -460 to 357 kcal/day, respectively). However, when separated by sex, only the equation by Muller et al., 2001 was accurate for males (bias: –85.3 ± 161.4; LOA: -402 to 231 kcal/day) and only the equation by Horie et al., 2007 was accurate for females (bias: 28.0 ± 162.4; LOA: -290 to 346 kcal/day). All other equations (5) underestimated mREE. ConclusionsThe equations by Muller et al., 2001 and Horie et al., 2007 can be used for estimating REE in adults with excess body weight. The use of body composition per se in not enough to ensure accuracy of predictive equations. Funding SourcesAlmased® (Almased USA, Inc., Wellington, FL, USA) and Alberta Diabetes Institute (University of Alberta, Edmonton, AB, Canada).

Food supply and individual quality influence seabird energy expenditure and reproductive success.

Breeding animals trade off maximizing energy output to increase their number of offspring with conserving energy to ensure their own survival, leading to an energetic ceiling influenced by external, environmental factors or by internal, physiological factors. We examined whether internal or external factors limited energy expenditure by supplementally feeding breeding black-legged kittiwakes varying in individual quality, based on earlier work that defined late breeders as low-quality and early breeders as high-quality individuals. We tested whether energy expenditure increased when food availability decreased in both low- and high-quality birds; we predicted this would only occur in high-quality individuals capable of sustaining high levels of energy expenditure. Here, we find that food-supplemented birds expended less energy than control birds because they spent more time at the colony. However, foraging trips of food-supplemented birds were only slightly shorter than control birds, implying that food-supplemented birds were limited by food availability at sea similarly to control birds. Late breeders expended less energy, suggesting that low-quality individuals may not intake the energy necessary for sustaining high-energy output. Food-supplemented birds had more offspring than control birds, but offspring number did not influence energy expenditure, supporting the idea that the birds reached an energy ceiling. Males and lighter birds expended more energy, possibly compensating for relatively higher energy intake. Chick-rearing birds were working near their maximum, with highest levels of expenditure for early-laying (high-quality) individuals foraging at sea. Due to fluctuating marine environments, kittiwakes may be forced to change their foraging behaviors to maintain the balance between reproduction and survival.

The influence of bright and dim light on substrate metabolism, energy expenditure and thermoregulation in insulin-resistant individuals depends on time of day

Aims/hypothesisIn our modern society, artificial light is available around the clock and most people expose themselves to electrical light and light-emissive screens during the dark period of the natural light/dark cycle. Such suboptimal lighting conditions have been associated with adverse metabolic effects, and redesigning indoor lighting conditions to mimic the natural light/dark cycle more closely holds promise to improve metabolic health. Our objective was to compare metabolic responses to lighting conditions that resemble the natural light/dark cycle in contrast to suboptimal lighting in individuals at risk of developing metabolic diseases.MethodsTherefore, we here performed a non-blinded, randomised, controlled, crossover trial in which overweight insulin-resistant volunteers (n = 14) were exposed to two 40 h laboratory sessions with different 24 h lighting protocols while staying in a metabolic chamber under real-life conditions. In the Bright day–Dim evening condition, volunteers were exposed to electric bright light (~1250 lx) during the daytime (08:00–18:00 h) and to dim light (~5 lx) during the evening (18:00–23:00 h). Vice versa, in the Dim day–Bright evening condition, volunteers were exposed to dim light during the daytime and bright light during the evening. Randomisation and allocation to light conditions were carried out by sequential numbering. During both lighting protocols, we performed 24 h indirect calorimetry, and continuous core body and skin temperature measurements, and took frequent blood samples. The primary outcome was plasma glucose focusing on the pre- and postprandial periods of the intervention.ResultsSpending the day in bright light resulted in a greater increase in postprandial triacylglycerol levels following breakfast, but lower glucose levels preceding the dinner meal at 18:00 h, compared with dim light (5.0 ± 0.2 vs 5.2 ± 0.2 mmol/l, n = 13, p=0.02). Dim day–Bright evening reduced the increase in postprandial glucose after dinner compared with Bright day–Dim evening (incremental AUC: 307 ± 55 vs 394 ± 66 mmol/l × min, n = 13, p=0.009). After the Bright day–Dim evening condition the sleeping metabolic rate was identical compared with the baseline night, whereas it dropped after Dim day–Bright evening. Melatonin secretion in the evening was strongly suppressed for Dim day–Bright evening but not for Bright day–Dim evening. Distal skin temperature for Bright day–Dim evening was lower at 18:00 h (28.8 ± 0.3°C vs 29.9 ± 0.4°C, n = 13, p=0.039) and higher at 23:00 h compared with Dim day–Bright evening (30.1 ± 0.3°C vs 28.8 ± 0.3°C, n = 13, p=0.006). Fasting and postprandial plasma insulin levels and the respiratory exchange ratio were not different between the two lighting protocols at any time.Conclusions/interpretationTogether, these findings suggest that the indoor light environment modulates postprandial substrate handling, energy expenditure and thermoregulation of insulin-resistant volunteers in a time-of-day-dependent manner.Trial registrationClinicalTrials.gov NCT03829982.FundingWe acknowledge the financial support from the Netherlands Cardiovascular Research Initiative: an initiative with support from the Dutch Heart Foundation (CVON2014–02 ENERGISE).Graphical abstract