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Despite the increased popularity of female elite road cycling, research to inform the fueling requirements of these endurance athletes is lacking. In this case study, we report for the first time the energetics of a female world-tour cyclist competing in the 2023 Tour de France Femmes, an 8-day race of the Union Cycliste Internationale. The 29-year-old athlete presented with oligomenorrhea and low T3 before the race. Total daily energy expenditure assessed with the doubly labeled water technique was 7,572 kcal/day (∼4.3 physical activity levels), among the highest reported in the literature to date for a female. Crank-based mean maximal power was consistent with female world-tour cyclists (5 min, mean 342 W, 4.8 W/kg; 20 min 289 W, 4.1 W/kg). The average daily energy intake measured with the remote food photography method (Stage Days 1–7) was 5,246 kcal and carbohydrate intake was 13.7 g/kg (range 9.7–15.9 g/kg), and 84 g/hr during stages, and an average fat intake of 15% of daily energy intake. An estimated 2,326 kcal/day energy deficit was evidenced in a 2.2 kg decrease in body mass. Notwithstanding the high carbohydrate intake, the athlete was unable to match the energy requirements of the competition. Despite signs of energy deficiency preexisting (oligomenorrhea and low T3), and other further developing during the race (weight loss), performance was in line with that of other world-tour cyclists and a best personal performance was recorded for the last stage. This case study emphasizes the need for further research to inform energy requirements for female athletes' optimal performance and health. [ABSTRACT FROM AUTHOR]

Continuous multiday ultramarathon competitions are increasingly popular and impose extreme energetic and nutritional demands on competitors. However, few data have been published on energy expenditure during these events. Here, we report doubly labeled water-derived measures of total energy expenditure (in kilocalories per day) and estimated physical activity level (PAL: total energy expenditure/basal metabolic rate) collected from five elite and subelite finishers (four males and one female, age 34.6 ± 4.9 years)—and nutritional intake data from the winner—of the Cocodona 250, a ∼402-km race in Arizona, and from a fastest-known-time record (one male, age 30 years) on the ∼1,315-km Arizona Trail. PAL during these events exceeded four times basal metabolic rate (Cocodona range: 4.34–6.94; Arizona Trail: 5.63). Combining the results with other doubly labeled water-derived total energy expenditure data from ultraendurance events show a strong inverse relationship between event duration and PAL (r2 =.68, p <.0001). Cocodona race duration was inversely, though not significantly, associated with PAL (r2 =.70, p =.08). Water turnover varied widely between athletes and was not explained by PAL or body mass. The Cocodona race winner met ∼53% of energy demand via dietary intake, 85.6% of which was carbohydrate, while ∼47% of energy demand was met via catabolism of body energy stores. Together, these results illustrate the energetic deficits incurred during competitive continuous multiday ultramarathon efforts and implicate macronutrient absorption and/or storage as key factors in ultramarathon performance. [ABSTRACT FROM AUTHOR]

Primates spend on average half as much energy as other placental mammals while expressing a wide range of lifestyles. However, little is known about how primates adapt their rate of energy use in the context of natural environmental variations. Using doubly labelled water, behavioral and accelerometric methods, we measured the total energy expenditure (TEE) and body composition of a population of Eulemur fulvus (N = 12) living in an agroforest in Mayotte. We show that the TEE of this medium-sized cathemeral primate is one of the lowest recorded to date in eutherians. Regression models show that individual variation in the rate of energy use is predicted by fat-free mass, body size, thigh thickness and maximum temperature. TEE is positively correlated with increasing temperature, suggesting that thermoregulation is an important component of the energy budget of this frugivorous species. Mass-specific TEE is only 10% lower than that of a closely related species previously studied in a gallery forest, consistent with the assertion that TEE varies within narrow physiological limits. As lemur communities include many species with unique thermoregulatory adaptations, circadian and/or seasonal temperature variations may have constituted a major selective pressure on the evolution of lemur metabolic strategies. [ABSTRACT FROM AUTHOR]

Summary: Objectives: We aimed to validate dietary assessment methods against the gold standard, doubly labeled water (DLW), for estimating total energy intake (TEI). Methods: PubMed, Scopus, Web of Science, and Google Scholar databases were searched until May 2023. Inclusion criteria encompassed studies involving participants aged 1–18 years, employing dietary assessment methods like food records, dietary histories, food frequency questionnaire (FFQ), or 24‐h recalls estimating TEI alongside DLW to measure total energy expenditure (TEE). Data were pooled using random‐effects meta‐analysis models. Results: Thirty‐three studies were identified, with sample sizes ranging from 9 to 118 participants. Meta‐analysis of 22 studies identified underestimation of TEI (mean difference [MD] = −262.9 kcal/day [95% CI: −380.0, −145.8]; I2 = 93.55%) for food records compared with TEE estimated by DLW. Other dietary assessment methods, including food recalls (n = 9) (MD = 54.2 kcal/day [95% CI: −19.8, 128.1]; I2 = 49.62%), FFQ (n = 7) (MD = 44.5 kcal/day [95% CI: −317.8, 406.8]; I2 = 94.94%), and diet history (n = 3) (MD = −130.8 kcal/day [95% CI: −455.8, 194.1]; I2 = 77.48%), showed no significant differences in TEI compared with DLW‐estimated TEE. All studies were of high quality. Conclusion: Food records may underestimate TEI, yet additional research is needed to identify the most accurate methods for assessing children's dietary intake. [ABSTRACT FROM AUTHOR]

Abstract Primates spend on average half as much energy as other placental mammals while expressing a wide range of lifestyles. However, little is known about how primates adapt their rate of energy use in the context of natural environmental variations. Using doubly labelled water, behavioral and accelerometric methods, we measured the total energy expenditure (TEE) and body composition of a population of Eulemur fulvus (N = 12) living in an agroforest in Mayotte. We show that the TEE of this medium-sized cathemeral primate is one of the lowest recorded to date in eutherians. Regression models show that individual variation in the rate of energy use is predicted by fat-free mass, body size, thigh thickness and maximum temperature. TEE is positively correlated with increasing temperature, suggesting that thermoregulation is an important component of the energy budget of this frugivorous species. Mass-specific TEE is only 10% lower than that of a closely related species previously studied in a gallery forest, consistent with the assertion that TEE varies within narrow physiological limits. As lemur communities include many species with unique thermoregulatory adaptations, circadian and/or seasonal temperature variations may have constituted a major selective pressure on the evolution of lemur metabolic strategies.

Previous studies have used the doubly labeled water method to evaluate the total energy expenditure (TEE) during Ironman, ultramarathon trail runs, and competitive road cycling. However, the technique has not been applied to a 24-hour cross-country mountain-bike event. Purpose: This case study aimed to measure the TEE, cycling metrics, and ad libitum nutrient/fluid intake during a 24-hour cross-country mountain-bike race. Methods: A trained male cyclist (41 y, 74.1 kg, 172.4 cm) received an oral dose of doubly labeled water prior to the 24-hour event for the calculations of TEE and water turnover. Nude body weight and urine samples were collected prerace, during the race, and postrace. Total nutrient intake and total fluid intake in addition to cycling metrics (speed, power output, cadence, and heart rate) were continuously recorded during the event. Results: The rider completed 383 km coupled with a vertical gain of 7737 m during the 24-hour event. Average speed, power, and heart rate were 16.3 (2) km·h−1, 122 (29) W, and 134 (18) beats·min–1, respectively. TEE and total nutrient intake were 41 and 23.5 MJ, respectively. Total carbohydrate intake was 1192 g with an average hourly intake of 58 (22) g·h−1. Total body weight was 75.3 and 72.3 kg prerace and postrace, respectively, with a measured ad libitum total fluid intake of 13.3 L and a water turnover of 17.2 L. Conclusions: These data provide novel insights for measures of TEE, total energy intake, and total fluid intake during an ultraendurance cross-country mountain-biking event and provide a foundation for future race/training needs. [ABSTRACT FROM AUTHOR]

Abstract Variations in physical activity energy expenditure can make accurate prediction of total energy expenditure (TEE) challenging. The purpose of the present study was to determine the accuracy of available equations to predict TEE in individuals varying in physical activity (PA) levels. TEE was measured by DLW in 56 adults varying in PA levels which were monitored by accelerometry. Ten different models were used to predict TEE and their accuracy and precision were evaluated, considering the effect of sex and PA. The models generally underestimated the TEE in this population. An equation published by Plucker was the most accurate in predicting the TEE in our entire sample. The Pontzer and Vinken models were the most accurate for those with lower PA levels. Despite the levels of accuracy of some equations, there were sizable errors (low precision) at an individual level. Future studies are needed to develop and validate these equations.

Humans require energy to sustain their daily activities throughout their lives. This narrative review aims to (a) summarize principles and methods for studying human energy expenditure, (b) discuss the main determinants of energy expenditure, and (c) discuss the changes in energy expenditure throughout the human life course. Total daily energy expenditure is mainly composed of resting energy expenditure, physical activity energy expenditure, and the thermic effect of food. Total daily energy expenditure and its components are estimated using variations of the indirect calorimetry method. The relative contributions of organs and tissues determine the energy expenditure under different physiological conditions. Evidence shows that energy expenditure varies along the human life course, at least in part due to changes in body composition, the mass and specific metabolic rates of organs and tissues, and levels of physical activity. This information is crucial to estimate human energy requirements for maintaining health throughout the life course. [ABSTRACT FROM AUTHOR]

Variations in physical activity energy expenditure can make accurate prediction of total energy expenditure (TEE) challenging. The purpose of the present study was to determine the accuracy of available equations to predict TEE in individuals varying in physical activity (PA) levels. TEE was measured by DLW in 56 adults varying in PA levels which were monitored by accelerometry. Ten different models were used to predict TEE and their accuracy and precision were evaluated, considering the effect of sex and PA. The models generally underestimated the TEE in this population. An equation published by Plucker was the most accurate in predicting the TEE in our entire sample. The Pontzer and Vinken models were the most accurate for those with lower PA levels. Despite the levels of accuracy of some equations, there were sizable errors (low precision) at an individual level. Future studies are needed to develop and validate these equations. [ABSTRACT FROM AUTHOR]

The application of stable isotope analysis (SIA) to the fields of ecology and animal biology has rapidly expanded over the past three decades, particularly with regards to water analysis. SIA now provides the opportunity to monitor migration patterns, examine food webs, and assess habitat changes in current and past study systems. While carbon and nitrogen SIA of biological samples have become common, analyses of oxygen or hydrogen are used more sparingly despite their promising utility for tracing water sources and animal metabolism. Common ecological applications of oxygen or hydrogen SIA require injecting enriched isotope tracers. As such, methods for processing and analyzing biological samples are tailored for enriched tracer techniques, which require lower precision than other techniques given the large signal-to-noise ratio of the data. However, instrumentation advancements are creating new opportunities to expand the applications of high-throughput oxygen and hydrogen SIA. To support these applications, we update methods to distill and measure water derived from biological samples with consistent precision equal to, or better than, ± 0.1 ‰ for δ17O, ± 0.3 ‰ for δ18O, ± 1 ‰ for δ2H, ± 2 ‰ for d-excess, and ± 15 per meg for Δ17O. [ABSTRACT FROM AUTHOR]

Summary: The measurement of habitual energy intake remains a challenge in nutrition research. High levels of misreporting, particularly among adults with obesity, have been observed when comparing self‐reported energy intake to energy expenditure assessed via the doubly labeled water technique. Little is known about misreporting in adults with class III obesity (body mass index ≥40 kg/m2). This systematic review assessed the representation of adults with class III obesity in dietary validation studies and the validity of self‐reported dietary energy intake for this group. Studies were included in this review if they: compared self‐reported energy intake assessment method(s) to doubly labeled water, had participants ≥18 years old, and included participants with class III obesity. Fifteen studies met these criteria. Of those, eight included information about the number of participants with class III obesity. Out of 1784 participants across eight studies, 63 (3.5%) participants had class III obesity, compared to 9.2% of US adults with class III obesity. Six studies provided data on validity of energy intake assessment for class III obesity, with five of these showing underreporting. Participants with class III obesity are underrepresented in dietary validation studies. Future research should explore the role of weight status on dietary reporting accuracy. [ABSTRACT FROM AUTHOR]

Some studies comparing persons with and without type 2 diabetes (T2DM) show no difference in resting energy expenditure (REE). However, the degree of glycemic control may be a crucial factor in determining energy requirements. Few studies have employed the doubly labeled water (DLW) method in persons with T2DM to objectively measure daily energy expenditure. To determine relationships between glycemia, body composition, and energy expenditure in adults with obesity and T2DM. We hypothesized that worse hyperglycemia, insulin resistance, and beta cell function would associate with higher resting and total energy expenditure (TEE). Two cohorts age 31–50 years were included: 78 with obesity and T2DM, 19 with normal weight and no chronic disease. Baseline data from clinical biomarkers, intravenous glucose tolerance tests, DXA and MRI for body composition, and dietary intakes were used in multivariable regression models to predict REE and TEE. Additionally, comparisons were made by categorizing participants as having controlled or uncontrolled glycemia based on glucose levels ≥175 mg/dL. REE was higher in participants with T2DM by 534.08 ± 74.35 kcal/d (p < 0.001). Higher fasting glucose and HbA1C levels associated with higher TEE. Abdominal SAT and VAT were also predictors in regression models accounting for 76 % of the variance in REE and 89 % of TEE. Participants with uncontrolled glycemia had 22 % higher adipose/lean ratio, two-fold higher VAT/SAT ratio, 21 % higher HOMA-IR score, and worse beta cell function (mean difference in HOMA2-%β of 74.09 ± 14.01, p < 0.001) than those with controlled glycemia. Both REE and TEE were significantly higher in uncontrolled glycemia, difference in REE of 154.17 ± 96.28 kcals/day (p = 0.04) and difference in TEE of 480.64 ± 215.45 kcals/day (p = 0.03). Poor beta cell function and uncontrolled glycemia associate with higher REE and TEE in persons with obesity and T2DM. This study is registered with clinicaltrials.gov identifier: NCT01239550. [ABSTRACT FROM AUTHOR]

Background: Previous data have demonstrated that Tour de France riders maintain total daily energy expenditure (TDEE) between 3.5 and 5.5 times the basal metabolic rate (×BMR). In contrast, TDEE for healthy male septuagenarians has been reported to average 1.3 to 2.0 ×BMR. Purpose: Measure the TDEE and water efflux during ultraendurance work in an older population during the cross-continent cycling Race Across America. Methods: A 4-man septuagenarian team (70 [1.6] y, 72.0 [5.1] kg) received an oral dose of doubly labeled water prior to completing the Race Across America (4817 km, 51,816 m of climbing) for TDEE calculation. Nude body weight measures were coupled with collected urine samples. Results: The race was completed in approximately 6.5 days (official time: 6 d, 13 h, and 13 min) with an average speed of 30.6 (0.7) km·h−1 (age-group course record). Body weight remained unchanged (prerace: 70.4 [5.8] kg, postrace: 70.0 [5.3] kg). TDEE was calculated over 3 race segments. TDEE varied between individual riders and segments throughout the continuous event (24.7 [4.2] MJ·24 h−1, 5900 [1015] kcals·24 h−1, 3.4 [0.5] ×BMR). Water efflux averaged 10.2 (0.8) L·24 h−1 resulting in a total turnover of 45.3 (3.9) L amounting to 1.5 (0.2) times initial total body water during the race. Conclusions: Highly active septuagenarians maintain body weight prerace to postrace, suggesting near energy balance when TDEE approaches 4 ×BMR. These values exceed twice those of previously observed healthy but less active septuagenarian men and are comparable to professional riders during portions of the Tour de France. Advanced age and high metabolic output are not mutually exclusive. [ABSTRACT FROM AUTHOR]

BackgroundPhysical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass.ObjectivesA study is presented of the association between FFM and physical activity in relation to age.MethodsIn a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution.ResultsPAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males

It is unknown whether the relative contribution to energy imbalance in amyotrophic lateral sclerosis (ALS) is due to decreased energy intake, or increased energy expenditure from hyper-metabolism and/or physical activity, or both. We studied 10 free-living sporadic ALS subjects with mild to moderate disease and 10 matched healthy controls to address this question. We estimated energy intake by 24-h recall in ALS subjects and three-day food diary in all. We estimated body composition by dual energy X-ray absorptiometry and resting metabolic rate by indirect calorimetry; and measured total daily energy expenditure (TEE) and physical activity-energy expenditure using doubly labeled water. Daily energy intake was no different between ALS subjects and controls. Despite lower fat-free mass, unadjusted TEE was higher in ALS subjects than controls (2844 ± 319 vs. 2505 ± 261 kcal/d, p = 0.005 by paired t-test). Compared to controls, hyper-metabolism occurred in 80% of ALS subjects. Physical activity-energy expenditure was higher in ALS subjects than controls (718 ± 262 kcal/d vs. 487 ± 196 kcal/d, p = 0.04). In controls, energy intake matched TEE; in ALS subjects TEE was higher than energy intake. We found higher TEE in ALS subjects than controls, with larger contribution to difference from physical activity-energy expenditure than hyper-metabolism. Although daily energy intake in ALS subjects was similar to that in controls, they were unable to compensate for increased energy needs. To accurately determine energy balance and optimize nutrition in ALS, future studies should consider measuring energy intake, energy expenditure, and physical activity. [ABSTRACT FROM AUTHOR]

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (

To determine the thermic effect of food (TEF) in a Chinese mixed diet in young people. During the study, the participants were weighed and examined for body composition every morning. The total energy expenditure (TEE) of the participants was measured by the doubly labelled water method for 7 days, and during this period, basal energy expenditure was measured by indirect calorimetry and physical activity energy expenditure was measured by an accelerometer. The value obtained by subtracting basal energy expenditure and physical activity energy expenditure from TEE was used to calculate TEF. Twenty healthy young students (18–30 years; 10 male) participated in the study. The energy intake of the participants was not significantly different from the Chinese Dietary Reference Intake of energy (P > 0.05). The percentage of energy from protein, fat and carbohydrate were all in the normal range. The intakes of fruits, milk and dietary fiber of the participants were significantly lower than those in the Chinese Dietary Guidelines (P < 0.05). There was no significant difference in the body weight of the participants during the experiment (P > 0.05). When adjusted for body weight, there was no significant difference in either TEE or basal energy expenditure between the male and female participants (P > 0.05). In addition, there was no significant difference in physical activity energy expenditure and TEF between the male and female participants (P > 0.05). The percentage of TEF in TEE was 8.73%. The percentage of TEF in TEE in a Chinese mixed diet in young people was significantly lower than 10% (P < 0.001). A value of 10% is usually considered to be the TEF in mixed diets as a percentage of TEE. [ABSTRACT FROM AUTHOR]

Total energy expenditure (TEE) is essential for understanding the growth, development, and physical activity of children and adolescents. This study aimed to summarize the existing evidence on TEE measured using the doubly labeled water (DLW) technique in children and adolescents aged 1–18 years. Furthermore, this review compared TEE between obese and normal-weight participants. This systematic review used the PubMed, ScienceDirect, Web of Science, and EBSCO databases. These studies were limited to those published in English between January 2000 and December 2021. Articles presenting objectively measured data on the TEE of children and adolescents aged 1–18 years measured using the DLW method were included. Physical activity level (PAL; TEE/basal metabolic rate [BMR]) and BMR data were also obtained. The search strategy identified 2,351 articles, of which 63 (n=4,283 children and adolescents; 45.4% male) met the selection criteria. The participants in the 10 studies were overweight or obese (n=413). In our study, TEE increased in male and female participants aged 1–18 years. PAL increased with age in males (y=0.0272x+1.3887, r2=0.511) and females (y=0.0199x+1.401, r2=0.335), and the slope of PAL with age did not differ between males and females. The TEE of obese and overweight participants was higher than that of normal-weight participants, but the slope of TEE did not differ between normal-weight (y=132.99x+702.24, r2=0.877) and obese individuals (y=136.18x+1,037.9, r2=0.842). In conclusion, this review provides convincing evidence that daily TEE progressively increases with growth in males and females aged 1–18 years.

Accurate methods for the prediction of the total energy expenditure and physical activity level (PAL) in community-dwelling older adults have not been established. Therefore, we examined the validity of estimating the PAL using an activity monitor (Active style Pro HJA-350IT, [ASP]) and proposed correction formulae for such populations in Japan. Data for 69 Japanese community-dwelling adults aged 65 to 85 years were used. The total energy expenditure in free-living conditions was measured with the doubly labeled water method and the measured basal metabolic rate. The PAL was also estimated from metabolic equivalent (MET) values obtained with the activity monitor. Adjusted MET values were also calculated with the regression equation of Nagayoshi et al. (2019). The observed PAL was underestimated, but significantly correlated, with the PAL from the ASP. When adjusted using the Nagayoshi et al. regression equation, the PAL was overestimated. Therefore, we developed regression equations to estimate the actual PAL (Y) from the PAL obtained with the ASP for young adults (X) as follows: women: Y = 0.949 × X + 0.205, mean ± standard deviation of the prediction error = 0.00 ± 0.20; men: Y = 0.899 × X + 0.371, mean ± standard deviation of the prediction error = 0.00 ± 0.17. [ABSTRACT FROM AUTHOR]

The estimation of energy expenditure is key to resolve ecological questions and conservation strategies. The puma (Puma concolor (Linnaeus, 1771)) has been the subject of several efforts to measure the daily energy expenditure (DEE). Most of the estimations have been made using movement or activity models that have been questioned because of discrepancies with kill rates. This study looks at one movement model estimation and validates it using doubly labeled water (DLW), which can also account for energy expenditures beyond those associated with activity. We captured six pumas (51.5 ± 9.9 (SD) kg) during the winter in Colorado that were GPS collared and injected with DLW for an approximately 3-week trial. We found that DEE obtained from the DLW (14.5 ± 6.1 MJ·day−1) did not differ from that estimated using the movement model or from the predicted allometric equation based on DLW studies on other mammals. Decreasing air temperature and increasing daily distance movement were correlated with increasing DEE for monitored pumas. Both DLW and movement models provide a reasonable proxy to estimate DEE at the population level but exhibit low precision in estimating individual values for free-ranging puma. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective: This study aimed to assess the agreement between the total energy expenditure (TEE) estimated by the activPAL® triaxial accelerometers (ACC) and the TEE measured by the doubly labeled water method (DLW), as well as to assess if these values differ between the classifications of body mass index (BMI). Materials and methods: This is a cross-sectional study. Low-income adult women (19-45y) with BMI ≥ 18.5 kg/m2 were included. Accelerometry data (activPAL®) were collected over 7 consecutive days, which were used to calculate TEE-ACC and compared with DLW data. The Bland-Altman method, concordance correlation coefficient and root mean square error were used to assess agreement between methods. Results: The sample consisted of 55 women with a mean age of 31 ± 5 years. The agreement between TEE-ACC and TEE-DLW showed a bias of -142.5 kcal (-7.1%). Among the BMI classifications, participants with normal weight show a bias of -417.1 kcal (-21.0%), participants with overweight, -87.5 kcal (-3.9%) and participants with obesity, 97.5 kcal (4.3%). Furthermore, the bias between the methods showed a significant and positive correlation with the body weight (r = 0.49; p < 0.01). Conclusion: The TEE-ACC estimates from activPAL® were reasonably accurate when compared to the TEE-DLW, especially in women with overweight and obesity, being much less accurate in individuals with normal weight.

Maintaining muscle mass and function during rehabilitation from anterior cruciate ligament injury is complicated by the challenge of accurately prescribing daily energy intakes aligned to energy expenditure. Accordingly, we present a 38-week case study characterizing whole body and regional rates of muscle atrophy and hypertrophy (as inferred by assessments of fat-free mass from dual-energy X-ray absorptiometry) in a professional male soccer player from the English Premier League. In addition, in Week 6, we also quantified energy intake (via the remote food photographic method) and energy expenditure using the doubly labeled water method. Mean daily energy intake (CHO: 1.9-3.2, protein: 1.7-3.3, and fat: 1.4-2.7 g/kg) and energy expenditure were 2,765 ± 474 and 3,178 kcal/day, respectively. In accordance with an apparent energy deficit, total body mass decreased by 1.9 kg during Weeks 1-6 where fat-free mass loss in the injured and noninjured limb was 0.9 and 0.6 kg, respectively, yet, trunk fat-free mass increased by 0.7 kg. In Weeks 7-28, the athlete was advised to increase daily CHO intake (4-6 g/kg) to facilitate an increased daily energy intake. Throughout this period, total bodymass increased by 3.6 kg (attributable to a 2.9 and 0.7 kg increase in fat free and fat mass, respectively). Our data suggest it may be advantageous to avoid excessive reductions in energy intake during the initial 6-8 weeks post anterior cruciate ligament surgery so as to limit muscle atrophy. [ABSTRACT FROM AUTHOR]

Prior studies have examined offshore sailing and energy strategies using accurate total energy expenditure (TEE) measurement in free-living conditions. However, no research has studied energy and water requirements during dinghy class sailing such as an Olympic event with concentrated training. This study aimed to investigate the TEE, physical activity level (PAL), and water turnover (rH2O) of collegiate dinghy sailors in a training camp using the doubly labeled water method. Eleven dinghy sailing collegiate athletes (nine males and two females) participated. The doubly labeled water method was used to determine the participants' TEE and PAL over 8 days (six training and two nontraining days). Participants trained approximately 7 hr/day on water. Body fat was measured using a stable isotope dilution method. The rH2O was estimated using deuterium turnover. The mean TEE, PAL, and rH2O were 17.30 ± 4.22 MJ/day (4,133 ± 1,009 kcal/day), 2.8 ± 0.3 (range: 2.1-4.1), and 3.3 ± 0.7 L/day (range: 2.6-4.5 L/day), respectively. To our knowledge, this was the first study to use the doubly labeled water method to determine TEE, PAL, and rH2O as references for competitive dinghy sailors in a spring training camp. Our results may serve as a reference to assist competitive dinghy sailors in determining their required nutritional support. [ABSTRACT FROM AUTHOR]

This case study follows a professional internationally capped female soccer player's two-year journey from eumenorrhea, through injury, to amenorrhea, and the challenges faced by the player and nutritionist. The two years are split into three sections: (Areta et al. 2013) longitudinal profiling of the player, (Baker et al. 2020) nutrition to support her return from injury, and (Beato et al. 2018) investigation into the observed secondary amenorrhea. The cause of amenorrhea was investigated through the assessment of energy availability via doubly labelled water, remote food photography, blood biomarkers and resting metabolic rate. Despite having secondary amenorrhea and anovulatory cycles, the player did not have low energy availability. This study shows the importance for practitioner's, particularly nutritionists, to not assume that all menstrual irregularities are caused by low energy availability and could be caused by a combination of factors (e.g., clinical, physiological, and psychological), which requires a multi-disciplinary investigation and intervention team. This study also showed that education needs to be provided about menstrual health to elite female soccer players as the player (i) believed that not having a period was beneficial for performance and unsure of possible health implications; (ii) was convinced that a one-day bleed indicated a regular menstrual cycle; and (iii) was reluctant to waste the practitioners time discussing menstrual issues and was nervous of finding out if she had an actual health issue. It is therefore crucial that players feel comfortable in discussing their menstrual status with practitioners to support their performance and long-term health. [ABSTRACT FROM AUTHOR]

Abstract Background Few studies on measuring human energy expenditure with the doubly labeled water method has been conducted in China. The sources and loss of water among human body have never been systematically evaluated. Less data can be available for the development of the recommendation on energy expenditure and water intake. The objective of this study was to determine the energy expenditure, water sources, and loss among young adults. Methods In this cross-sectional study, 25 participants were recruited. Double-labeled water was used to determine their energy expenditure. Water loss through skin evaporation and respiration of the lungs and water sources from metabolic water were calculated using corresponding formula, respectively. Water loss through excretion of urine was recorded and evaluated using “3-day, 24-h, real-time urine excretion record” method. All urine samples were collected and weighed in the 3 days. Water loss through excretion of feces was evaluated using “3-day, 24-h, real-time fecal-excretion record” method. All fecal samples were collected and tested by the direct drying method. Water sources from fluid intake were recorded by “7-day, 24-h, real-time fluid intake record” method. Water intake from food was calculated and tested by the weighing method combined with the duplicate portion method and the direct drying method in the 3 days. Results The energy expenditure of males was 2187 kcal/d, and that of females was 1987 kcal/d. The median fluid intake, water intake from food, and metabolic water were 887, 1173 and 246 mL, respectively, which accounted for 38.8%, 50.3%, and 11.2% of total water sources. There was a gender difference in the percentage of metabolic water (Z = − 2.135, P = 0.033). The water loss through urine excretion, skin evaporation, respiration, and feces excretion was 1295, 172, 149 and 64 mL, respectively, which accounted for 76.5%, 10.3%, 9.5%, and 3.6% of the total water losses. Gender differences in the amount of water loss through respiration and skin evaporation were found (Z = − 4.125, P

Intraspecific variability in foraging behavior has been documented across a range of taxonomic groups, yet the energetic consequences of this variation are not well understood for many species. Understanding the effect of behavioral variation on energy expenditure and acquisition is particularly crucial for mammalian carnivores because they have high energy requirements that place considerable pressure on prey populations. To determine the influence of behavior on energy expenditure and balance, we combined simultaneous measurements of at-sea field metabolic rate (FMR) and foraging behavior in a marine carnivore that exhibits intraspecific behavioral variation, the California sea lion (Zalophus californianus). Sea lions exhibited variability in at-sea FMR, with some individuals expending energy at a maximum of twice the rate of others. This variation was in part attributable to differences in diving behavior that may have been reflective of diet; however, this was only true for sea lions using a foraging strategy consisting of epipelagic (

Context Energy expenditure predictive equations can generate inaccurate estimates for overweight or obese individuals. Objective The objective of this review was to determine which predictive equations for resting energy expenditure (REE) and total energy expenditure (TEE) have the lowest bias and the highest precision in adults with overweight and obesity. Data Sources Searches were performed in January 2022 in MEDLINE, Web of Science, Scopus, CENTRAL, and the gray literature databases. Data Extraction Meta-analyses were performed with equations included in more than 1 study. The DerSimonian and Laird random-effects model and the I2 statistic were used to quantify heterogeneity in the quantitative analyses. The Egger test was performed to assess potential publication biases, and metaregressions were conducted to explore the heterogeneity. Findings were presented separated by participants' body mass index classification (overweight and obesity). Data Analysis Sixty-one studies were included. The FAO/WHO/UNU (1985) equation, which uses only body weight in its formula, showed the lowest bias in estimating REE (mean difference [MD] = 8.97 kcal; 95% CI = –26.99; 44.94). In the subgroup analysis for individuals with obesity, the Lazzer (2007) equation showed the lowest bias (MD = 4.70 kcal; 95% CI = –95.45; 104.86). The Harris–Benedict equation (1919) showed the highest precision values for individuals with overweight (60.65%) and for individuals with obesity (62.54%). Equations with body composition data showed the highest biases. The equation proposed by the Institute of Medicine (2005) showed the lowest bias (MD = –2.52 kcal; 95% CI = –125.94; 120.90) in estimating the TEE. Most analyses showed high heterogeneity (I2 > 90%). There was no evidence of publication bias. Conclusion For individuals with overweight, the FAO/WHO/UNU (1985) and the Harris–Benedict equations (1919) showed the lowest bias and the highest precision in predicting the REE, respectively. For individuals with obesity, the Harris–Benedict equation (1919) showed the highest precision and the Lazzer equation (2007) showed the lowest bias. More studies are needed on predictive equations to estimate the TEE. Systematic Review Registration PROSPERO registration no. CRD42021262969. [ABSTRACT FROM AUTHOR]

Research on world-class athletes in endurance events, such as cycling Grand Tours, has reported extreme levels of total energy expenditure. However, it has been argued that over extended periods, such as months, sustained energy expenditure is capped at approximately 2.5 times the basal metabolic rate. Triathlon is particularly notable for its high energetic demands due to its multimodal nature, requiring athletes to maintain high training volumes. In this case study, we analyzed the total energy expenditure of world-class triathlete Kristian Blummenfelt using doubly labelled water over two specific periods, along with three years of training data. Total energy expenditure ranged from 7,019-8,506 kcal/day. Reported energy intake ranged from 4,899 to 6,360 kcal/day. The annual training volumes for the years 2020-2022 were 1,480, 1,350 and 1,308 hours, respectively, following a pyramidal intensity distribution. Approximately 53% of the entire three-year period matched with the doubly labeled water measurement periods in terms of training volume, indicating that the recorded total energy expenditure is representative of the majority of the observed data. Hence, the greater part of the three-year period likely exceeds the proposed metabolic ceiling for sustained total energy expenditure. This not only questions the validity of the current metabolic limits but also suggests a new perspective on what is physiologically achievable in world-class athletes.

Background: Doubly labeled water is gold standard for measuring total energy expenditure (TEE). Measurements using the method are sensitive to the isotope dilution space ratio (DSR). Accuracy and precision of the method might be improved if we could identify factors influencing DSR., Objectives: We evaluated the potential associations of age, sex, ethnicity, anthropometry, body composition, turnover rates of the isotopes, and geographical elevation with DSR., Methods: We used univariate regression analysis to explore the relationships between the continuous variables and analysis of variance to test the relationships between the categorical variables with DSR. Subsequently, we used general linear model (GLM) and 1-way analysis of variance to evaluate the simultaneous associations of age, sex, ethnicity, fat-free mass (FFM) and fat mass (FM) on DSR., Results: From 5678 measurements complied from studies around the world with diverse ethnicity and living at various elevations, the mean DSR was 1.0364 ± 0.0141. No meaningful physiologic effect of any of the continuous and categorical variable on DSR was detected. General linear model analysis revealed no effect of FFM and FM (P > 0.33) on DSR, but DSR decreased with age (P < 0.001) among those aged 60 y and older regardless of sex. Among the Whites who were younger than 60 y, DSR was not related to FFM and FM (P = 0.73) but was affected by both age and sex (P < 0.001)., Conclusions: Previous estimates of age-related decline in TEE may have overestimated TEE at age 90 y. Validation studies on older participants are required to confirm this finding., Competing Interests: Conflict of interest WWW reports administrative support was provided by Baylor College of Medicine. JRS reports administrative support and article publishing charges were provided by University of Aberdeen. MLN is a Deputy Editor of the Journal of Nutrition but played no role in the Journal’s evaluation of the manuscript. The other authors report no conflicts of interest., (Copyright © 2024 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Introduction: Multiple factors contribute to increased risk of dehydration in amyotrophic lateral sclerosis (ALS), which contributes to shortened survival independent of nutritional status. The assessment of hydration by doubly labeled water is restricted due to the limited availability of this gold standard technique for clinical use. This prompted us to examine the utility of urine-specific gravity (USG) as a predictor of hydration need in ALS subjects. Material and Methods: Using data from a multicenter study of 80 ALS subjects with 250 visits, we conducted a secondary analysis of the original data set from doubly labeled water experiments. We used a cross-section of the data (one visit per 75 subjects) in the model selection step ("test set"), and a repeated measures analysis in the validation step with data from 63 subjects and 142 follow-up visits. The sensitivity to detect inadequate water turnover rate (a surrogate for water intake) was the goal of the predictive model presented for clinical use. Results and discussion: The final predictive model to estimate water requirement included USG, gender, body mass index, and the ALSFRS gross motor subscale score. We developed a best-fit equation to estimate water intake from USG, determine hydration status, and improve clinical care of real-world ALS subjects. [ABSTRACT FROM AUTHOR]

In the Men's Lifestyle Validation Study (2011–2013), we examined the validity and relative validity of a physical activity questionnaire (PAQ), a Web-based 24-hour recall (Activities Completed Over Time in 24 Hours (ACT24)), and an accelerometer by multiple comparison methods. Over the course of 1 year, 609 men completed 2 PAQs, two 7-day accelerometer measurements, at least 1 doubly labeled water (DLW) physical activity level (PAL) measurement (n  = 100 with repeat measurements), and 4 ACT24s; they also measured their resting pulse rate. A subset (n  = 197) underwent dual-energy x-ray absorptiometry (n  = 99 with repeated measurements). The method of triads was used to estimate correlations with true activity using DLW PAL, accelerometry, and the PAQ or ACT24 as alternative comparison measures. Estimated correlations of the PAQ with true activity were 0.60 (95% confidence interval (95% CI): 0.52, 0.68) for total activity, 0.69 (95% CI: 0.61, 0.79) for moderate-to-vigorous physical activity (MVPA), and 0.76 (95% CI: 0.62, 0.93) for vigorous activity. Corresponding correlations for total activity were 0.53 (95% CI: 0.45, 0.63) for the average of 4 ACT24s and 0.68 (95% CI: 0.61, 0.75) for accelerometry. Total activity and MVPA measured by PAQ, ACT24, and accelerometry were all significantly correlated with body fat percentage and resting pulse rate, which are physiological indicators of physical activity. Using a combination of comparison methods, we found the PAQ and accelerometry to have moderate validity for assessing physical activity, especially MVPA, in epidemiologic studies. [ABSTRACT FROM AUTHOR]

Purpose: Accurate measurement of energy expenditure (EE) using doubly labeled water depends on the estimate of total body water (TBW). The aims of this study were to 1) assess the accuracy of a new approach for estimating TBW and EE during high-energy turnover and 2) assess the accuracy of day-to-day assessment of EE with this new approach. Methods: EE was measured in six healthy subjects (three male) for 5 consecutive days using three doubly labeled water methods: 1) the plateau, 2) slope-intercept, and 3) overnight-slope method, with whole-room indirect calorimetry as reference method. Urine samples were collected every evening and morning. High EE (physical activity level of >2.5) was achieved by cycling 4 h·d−1. Results: Physical activity level was 2.8 ± 0.1. TBW values were 41.9 ± 6.1, 38.4 ± 5.7, and 40.4 ± 5.8 L for the plateau, slope-intercept, and overnight-slope methods, respectively. The overnight-slope method showed the highest accuracy in estimated CO2 production, when compared with indirect calorimetry over the complete 5-d period (mean ± SD difference, 0.9% ± 1.6%). The plateau method significantly overestimated CO2 production by 4.7% ± 2.6%, whereas the slope-intercept method underestimated CO2 production (−3.4% ± 2.3%). When CO2 production was assessed per day, the overnight-slope method showed an average difference of 9.4% ± 4.5% to indirect calorimetry. Conclusions: The overnight-slope method resulted in a more accurate estimation of CO2 production and EE compared with the plateau or slope-intercept method over a 5-d period in high physical activity conditions. Day-to-day determination of EE using the overnight-slope method was more accurate than diet recall and several standard prediction equations in athletes. [ABSTRACT FROM AUTHOR]

Meeting the energy demands of prolonged arduous expeditions and endurance sport may be a significant barrier to success. Expedition rowing is associated with high levels of body-mass loss, reflecting the challenge of meeting energy expenditure in this exacting environment. Purpose: To use the doubly labeled water (DLW) technique to calculate the total energy expenditure (TEE) and body-composition changes of two 28-y-old healthy male athletes during a 50-d continuous and unsupported row around Great Britain. Methods: A measured dose of DLW was taken at the start of 2 separate study periods (days 5-19 and 34-48) followed by sequential urine collection, which was analyzed on return to land. Results: Mean TEE was 15.3 MJ/d: athlete 1, 16.4 MJ/d; athlete 2, 14.9 MJ/d. Athlete 1 lost 11.2 kg and athlete 2 lost 14.9 kg of body mass during the row. Average energy provision was 19.1 MJ per 24-h ration pack. Conclusions: These results highlight the difficulty of maintaining energy balance during expedition rowing. A starvation state was observed despite dietary provision in excess of estimated energy expenditure, indicating that nutritional strategy rather than caloric availability was at fault. The authors recommend that future expeditions prioritize thorough testing and the individualization of rations to ensure that they are both palatable and practical during the weeks to months at sea. [ABSTRACT FROM AUTHOR]

Accurate methods for the prediction of the total energy expenditure and physical activity level (PAL) in community-dwelling older adults have not been established. Therefore, we examined the validity of estimating the PAL using an activity monitor (Active style Pro HJA-350IT, [ASP]) and proposed correction formulae for such populations in Japan. Data for 69 Japanese community-dwelling adults aged 65 to 85 years were used. The total energy expenditure in free-living conditions was measured with the doubly labeled water method and the measured basal metabolic rate. The PAL was also estimated from metabolic equivalent (MET) values obtained with the activity monitor. Adjusted MET values were also calculated with the regression equation of Nagayoshi et al. (2019). The observed PAL was underestimated, but significantly correlated, with the PAL from the ASP. When adjusted using the Nagayoshi et al. regression equation, the PAL was overestimated. Therefore, we developed regression equations to estimate the actual PAL (Y) from the PAL obtained with the ASP for young adults (X) as follows: women: Y = 0.949 × X + 0.205, mean ± standard deviation of the prediction error = 0.00 ± 0.20; men: Y = 0.899 × X + 0.371, mean ± standard deviation of the prediction error = 0.00 ± 0.17.

Background: Few studies on measuring human energy expenditure with the doubly labeled water method has been conducted in China. The sources and loss of water among human body have never been systematically evaluated. Less data can be available for the development of the recommendation on energy expenditure and water intake. The objective of this study was to determine the energy expenditure, water sources, and loss among young adults. Methods: In this cross-sectional study, 25 participants were recruited. Double-labeled water was used to determine their energy expenditure. Water loss through skin evaporation and respiration of the lungs and water sources from metabolic water were calculated using corresponding formula, respectively. Water loss through excretion of urine was recorded and evaluated using "3-day, 24-h, real-time urine excretion record" method. All urine samples were collected and weighed in the 3 days. Water loss through excretion of feces was evaluated using "3-day, 24-h, real-time fecal-excretion record" method. All fecal samples were collected and tested by the direct drying method. Water sources from fluid intake were recorded by "7-day, 24-h, real-time fluid intake record" method. Water intake from food was calculated and tested by the weighing method combined with the duplicate portion method and the direct drying method in the 3 days. Results: The energy expenditure of males was 2187 kcal/d, and that of females was 1987 kcal/d. The median fluid intake, water intake from food, and metabolic water were 887, 1173 and 246 mL, respectively, which accounted for 38.8%, 50.3%, and 11.2% of total water sources. There was a gender difference in the percentage of metabolic water (Z = − 2.135, P = 0.033). The water loss through urine excretion, skin evaporation, respiration, and feces excretion was 1295, 172, 149 and 64 mL, respectively, which accounted for 76.5%, 10.3%, 9.5%, and 3.6% of the total water losses. Gender differences in the amount of water loss through respiration and skin evaporation were found (Z = − 4.125, P < 0.001; Z = − 3.723, P < 0.001). Conclusions: Energy expenditure of male was higher than that of female. The first major water sources was water intake from food in this study, and the first major water loss was urine excretion. Trial registration The study was registered on the website of Chinese clinical trial registry, and the code of identification is ChiCTR1900028746. [ABSTRACT FROM AUTHOR]

Activity-related energy expenditure (AEE) correlates with physical activity volume; however, between-person differences in body size and walking economy (net VO2) can influence AEE. The ratio of total energy expenditure (TEE) and resting energy expenditure (REE) estimates physical activity level (PAL) relative to body mass, yet does not account for variance in walking economy. The activity-related time equivalent (ARTEwalk) circumvents such constraints by adjusting for individual-specific walking economy. Herein, we compared AEE, PAL, and ARTEwalk index in a cohort (n = 81) of postmenopausal women while examining possible associations with biomarkers of cardiometabolic health. Secondary analyses were performed on postmenopausal women dichotomized above/below age group 50th percentile for body fat percent. TEE was reduced by 10% for the thermogenesis of digestion wherein AEE was calculated by subtracting REE from adjusted TEE. PAL was calculated as the ratio of TEE/REE. AEE was divided by the mean net energy expenditure of nongraded walking to calculate the ARTEwalk index. Between-group differences were not detected for AEE or PAL. However, the ARTEwalk index revealed that participants with less adiposity were more physically active (258 ± 149 vs. 198 ± 115 min·day-1; P = 0.046; g = 0.46). AEE and PAL did not correlate with cardiorespiratory fitness or biomarkers of cardiometabolic health. Cardiorespiratory fitness (r = 0.32), arterial elasticity (r = 0.24), total cholesterol/HDL-c ratio (r = -0.22), and body fat% (r = -0.24) were correlated with ARTEwalk. The ARTEwalk index may offer utility in detecting possible differences in physical activity volume among postmenopausal women and appears better associated with cardiometabolic biomarkers compared with AEE or PAL. [ABSTRACT FROM AUTHOR]

Among 683 participants in the Women's Lifestyle Validation Study (2010–2012), we evaluated the performance of a self-administered physical activity questionnaire (PAQ) and Web-based 24-hour recalls (Activities Completed Over Time in 24 Hours (ACT24)) using multiple comparison methods. Two PAQs, 4 ACT24s, two 7-day accelerometer measurements, 1 doubly labeled water (DLW) physical activity level (PAL) measure (repeated; n  = 90), and 4 resting pulse rate measurements were collected over 15 months. The deattenuated correlation between the PAQ and DLW PAL was 0.41 (95% confidence interval (CI): 0.33, 0.49) for total physical activity (PA) and 0.40 (95% CI: 0.31, 0.48) for moderate-to-vigorous PA (MVPA). These correlations were similar when using accelerometry as the comparison method. Single and averaged ACT24 measurements had lower correlations with DLW and accelerometry as comparison methods. The PAQ showed inverse correlations with DLW body fat percentage and resting pulse rate. Using the method of triads, the estimated correlation of the PAQ with true total PA was 0.54 (95% CI: 0.47, 0.62) and that with true MVPA was 0.60 (95% CI: 0.52, 0.69). For averaged ACT24, the estimated correlations were 0.50 (95% CI: 0.43, 0.59) for total PA and 0.47 (95% CI: 0.39, 0.58) for MVPA, and for averaged accelerometry, these estimated correlations were 0.72 (95% CI: 0.64, 0.81) and 0.62 (95% CI: 0.53, 0.71), respectively. The PAQ provided reasonable validity for total PA and MVPA. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to examine the shape of the relationship between physical activity (PA) and total energy expenditure (TEE) and to explore the role of energy balance status (negative, stable, positive) in influencing this association. Methods : Cross-sectional. Participants were 584 older adults (50-74 yr) participating in the Interactive Diet and Activity Tracking in AARP study. TEE was assessed by doubly labeled water and PA by accelerometer. The relationship between PA and TEE was assessed visually and using nonlinear methods (restricted cubic splines). Percent weight change (>3%) over a 6-month period was used as a proxy measurement of energy balance status. Results : TEE generally increased with increasing deciles of PA averaging 2354 (SD, 351) kcal[middle dot]d-1 in the bottom decile to 2693 (SD, 480) kcal[middle dot]d-1 in the top decile. Cubic spline models showed an approximate linear association between PA and TEE (linear relation, P < 0.0001; curvature, P = 0.920). Results were similar in subgroup analyses for individuals classified as stable or positive energy balance. For those in negative energy balance, TEE was generally flat with increasing deciles of PA averaging 2428 (SD, 285) kcal[middle dot]d-1 in the bottom decile to 2372 (SD, 560) kcal[middle dot]d-1 in the top decile. Conclusions: Energy balance status seems to play an important role in the relationship between PA and TEE. When in a positive energy balance, the relationship between TEE and PA was consistent with an additive model; however, when energy balance was negative, TEE seems to be consistent with a constrained model. These findings support PA for weight gain prevention by increasing TEE; however, the effect of PA on TEE during periods of weight loss may be limited. An adequately powered, prospective study is warranted to confirm these exploratory findings. [ABSTRACT FROM AUTHOR]

Background: Given the utility of the doubly labeled water (DLW) method for determination of energy expenditure, additional techniques for isotope analysis of the samples are welcome. Laser-based instruments are one such new analytical tool, but their accuracy and feasibility for DLW studies are grossly understudied.Objectives: We assessed the accuracy of laser-based isotope ratio measurements as part of the DLW method for estimation of carbon dioxide production rate (rCO2) and total energy expenditure (TEE), in between-group comparison study designs.Methods: Urine samples from a previous study were analyzed with a laser-based instrument [off-axis integrated cavity output spectroscopy (OA-ICOS)]. In that study, participants consumed a high-, moderate-, or low-carbohydrate diet for 20 wk; urine samples were obtained in weeks 18-20 before and after a 2H- and 18O-enriched water dose. Isotope ratios (δ2H and δ18O), rCO2, and TEE calculated by standard methods were compared to results previously obtained with the standard technique of isotope ratio mass spectrometry (IRMS). Bias, SD, and bias ± 1.96SD bands between IRMS and OA-ICOS were computed.Results: The between OA-ICOS and IRMS rCO2 and TEE trends were equivalent (within 1.2% and 4.1%, respectively), in spite of the differences in measured δ18O values at high enrichment levels. The OA-ICOS δ18O values displayed an increasing offset from the IRMS results as the 18O enrichment increased (mean ± SD 4.6-5.7‰ ± 2‰ offset at the time point with highest 18O enrichment, ∼135‰), whereas the hydrogen isotope ratio (δ2H) differed only slightly between the methods (mean offset -4.9‰ for all time points). The between-diet differences in TEE from the previous study were recapitulated with a smaller subset of participants and time points.Conclusions: OA-ICOS analysis is an accurate and feasible technique for the DLW method. Given the δ18O offset observed at high enrichment, validation of each OA-ICOS instrumental setup against established methods (e.g., IRMS) is recommended. [ABSTRACT FROM AUTHOR]

During the past 60 years, mammalian hibernation (i.e., seasonal torpor) has been interpreted as a physiological adaptation for energy economy. However, direct field comparisons of energy expenditure and torpor use in hibernating and active free-ranging animals are scarce. Here, we followed the complete hibernation cycle of a fat-storing hibernator, the marsupial Dromiciops gliroides, in its natural habitat. Using replicated mesocosms, we experimentally manipulated energy availability and measured torpor use, hibernacula use, and social clustering throughout the entire hibernation season. Also, we measured energy flow using daily food intake, daily energy expenditure (DEE), and basal metabolic rate (BMR) in winter. We hypothesized that when facing chronic caloric restriction (CCR), a hibernator should maximize torpor frequency to compensate for the energetic deficit, compared with individuals fed ad lib. (controls). However, being torpid at low temperatures could increase other burdens (e.g., cost of rewarming, freezing risks). Our results revealed that CCR animals, compared with control animals, did not promote heat conservation strategies (i.e., clustering and hibernacula use). Instead, they gradually increased torpor frequency and reduced DEE and, as a consequence, recovered weight at the end of the season. Also, CCR animals consumed food at a rate of 50.8 kJ d-1, whereas control animals consumed food at a rate of 98.4 kJ d-1. Similarly, the DEE of CCR animals in winter was 47:3 ± 5:64 kJ d-1, which was significantly lower than control animals (DEE p 88:0 ± 5:84 kJ d-1). However, BMR and lean mass of CCR and control animals did not vary significantly, suggesting that animals maintained full metabolic capacities. This study shows that the use of torpor can be modulated depending on energy supply, thus optimizing energy budgeting. This plasticity in the use of heterothermy as an energy-saving strategy would explain the occurrence of this marsupial in a broad latitudinal and altitudinal range. Overall, this study suggests that hibernation is a powerful strategy to modulate energy expenditure in mammals from temperate regions. [ABSTRACT FROM AUTHOR]

Background: Obesity prevalence in youth with spina bifida is higher than in their typically developing peers. Obesity is associated with lifelong medical, psychological, and economic burdens. Successful prevention or treatment of obesity in individuals with spina bifida is compromised by (1) the lack of valid and reliable methods to identify body fat in a clinical setting and (2) limited data on energy expenditure that are necessary to provide daily caloric recommendations., Objective: The objectives of this study will be to develop 2 algorithms for use in youth with spina bifida in a clinical setting, one to model body fat and one to predict total daily energy expenditure. In addition, physical activity and dietary intake will be described for the sample., Methods: This multisite, prospective, national clinical study will enroll 232 youth with myelomeningocele aged 5 to 18 years (stratified by age and mobility). Participants will be enrolled for 1 week. Data obtained include 4 measures of body composition, up to 5 height measures, a ramped activity protocol, and a nutrition and physical activity screener. Participants will wear an accelerometer for the week. On the final study day, 2 samples of urine or saliva, which complete the doubly labeled water protocol, will be obtained. The analysis will include descriptive statistics, Bland-Altman plots, concordance correlation, and regression analysis., Results: The study received extramural federal funding in July 2019. Data collection was initiated in March 2020. As of April 2024, a total of 143 (female participants: n=76, 53.1%; male participants: n=67, 46.9%) out of 232 participants have been enrolled. Data collection is expected to continue throughout 2024. A no-cost extension until November 2025 will be requested for data analysis and dissemination of findings., Conclusions: This study furthers previous pilot work that confirmed the acceptability and feasibility of obtaining alternate height, body composition, and energy expenditure measures. The findings from this study will enhance screening, prevention, and treatment of abnormal weight status by facilitating the accurate identification of youths' weight status category and recommendations of daily caloric needs for this population that is at higher risk of obesity. Furthermore, the findings have the potential to impact outcomes for youth diagnosed with disabilities other than spina bifida who experience similar challenges related to alterations in body composition or fat distribution or measurement challenges secondary to mobility issues or musculoskeletal problems., International Registered Report Identifier (irrid): DERR1-10.2196/52779., (©Michele Polfuss, Kathryn Smith, Betsy Hopson, Andrea Moosreiner, Chiang-Ching Huang, Michele N Ravelli, Dan Ding, Zijian Huang, Brandon G Rocque, Rosemary White-Traut, Alexander Van Speybroeck, Kathleen J Sawin. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 02.07.2024.)

Background & Aims: Track and field sprinters must obtain an optimal body composition to improve sprint performance. To successfully change body composition, it is important to evaluate the estimated energy requirements (EER) and fluctuations in total energy expenditure (TEE). However, methods to accurately evaluate the EER and TEE in sprinters have not been fully investigated. The aim of this study was to compare currently used methods with the doubly labeled water (DLW) method, which is currently the gold standard for evaluating EER and TEE., Methods: Ten male collegiate sprinters participated in the study. We evaluated TEE DLW and compared it with the EER calculated using two equations used by the National Institute of Health and Nutrition (NIHN) and the Japan Institute of Sports Sciences (JISS). In addition, we evaluated the TEE from the activity record (AR) and triaxial accelerometer (ACC)., Results: TEE DLW (3172 ± 415 kcal/day) was not significantly different from EER NIHN (p = 0.076) or EER JISS (p = 0.967). In addition, there were no significant differences between TEE DLW and TEE AR (p = 0.218). However, two accelerometer-derived equations used to evaluate TEE were found to have underestimated (2783 ± 377 kcal/day, p < 0.001) and overestimated (3405 ± 369 kcal/day, p = 0.009) the TEE., Conclusion: Our results suggest that EER NIHN and EER JISS may be useful in evaluating the EER of collegiate male sprinters on a group basis, and AR may be more accurate than ACC in evaluating the TEE. These results may be helpful when considering nutritional support for male collegiate sprinters., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.)

Background: Water is one of the most essential nutrients for life. The water turnover (WT), total body water (TBW), and total energy expenditure (TEE) can be measured using the doubly labeled water (DLW) method. WT and TBW are lower in older adults than in young adults, and the former are susceptible to dehydration, necessitating to identify predictors of the WT in older adults., Objectives: The current study aimed to examine the association between WT and physical activity, physical function, and body composition in Japanese adults aged ≥65 y and identify predictors for WT in this population., Methods: This study enrolled 133 older adults (women, n = 61; men, n = 72) aged 65-88 y. WT, TBW, TEE, fat-free mass (FFM), and percent body fat (%Fat) were determined using the DLW method. The fitness age score (FAS) was obtained from 5 physical fitness tests. Physical activity and the step count were assessed using a previously validated triaxial accelerometer. Multiple regression analyses were performed with WT as the dependent variable., Results: WT was positively associated with weight, physical activity level (PAL), moderate-vigorous physical activity, and TEE, and negatively associated with sedentary behavior. We examined potential predictors for WT using age, sex, height, weight, FFM, %Fat, TEE, PAL, and FAS in older Japanese adults., Conclusions: Our results confirmed that age, sex, weight, FFM, TEE, and PAL are the potential predictors of WT in older Japanese adults aged ≥65 y., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background Establishing energy requirements in infants and young children is important in developing age-appropriate diet recommendations but most published guidelines for energy requirements have 1 or more limitations related to the data underlying the calculations. Objective To develop a comprehensive set of daily energy requirements for infants and young children aged 0–24 mo meeting the ideals of worldwide applicability to all healthy children based on the use of the doubly labeled water (DLW) technique to measure total energy expenditure (TEE), the use of recent, international growth charts, and calculation of values across a wide range of body weight. Methods Daily estimated energy requirements (EERs) were calculated in 1-mo increments from 0 to 24 mo for boys, girls, and combined, using as inputs the following: 1) TEE measured using the DLW technique, 2) energy deposition estimates from the Institute of Medicine, and 3) body weight values from the 25th to 75th percentiles from the 2006 WHO growth charts. EERs were combined for age groups 0 to <6, 6–8, 9–11, and 12–24 mo by averaging EERs from individual months. The EER calculations were supported by a systematic literature review and a meta-regression of existing studies. Results Energy requirements naturally increase with age and are slightly higher in boys than in girls. The EERs derived in this study are similar to those in other recent international efforts. Conclusions This updated set of EERs for infants and young children expand and improve upon the methodology used to establish previous published guidelines. These estimates have multiple potential uses including planning age-appropriate menus for the complementary feeding period, the development of foods that are more precisely targeted to the needs of infants and children at particular ages, and establishing macronutrient requirements within specific age groups based on a percentage of energy, such as dietary fat. [ABSTRACT FROM AUTHOR]

Introduction: Exercise usually results in less weight loss than expected. This suggests increased energy intake and/or deceased expenditure counteract the energy deficit induced by exercise. The aim of this study was to evaluate changes in components of daily energy expenditure (doubly labeled water and room calorimetry) after 24 wk of exercise training with two doses of aerobic exercise. Methods: This was an ancillary study in 42 (29 women, 13 men) sedentary, middle-age (47.8 ± 12.5 yr) individuals with obesity (35 ± 3.7 kg⋅m-2) enrolled in the Examination of Mechanisms of Exercise-induced Weight Compensation study. Subjects were randomized to three groups: healthy living control group (n = 13), aerobic exercise that expended 8 kcal⋅kg-1 of body weight per week (8 KKW, n = 14), or aerobic exercise that expended 20 kcal per kilogram of weight per week (20 KKW, n =15). Total daily energy expenditure (TDEE) was measured in free-living condition by doubly labeled water and in sedentary conditions in a metabolic chamber over 24 h (24EE). Energy intake was calculated over 14 d from TDEE before and after the intervention using the intake-balance method. Results: Significant weight loss occurred with 20 KKW (-2.1 ± 0.7 kg, P = 0.04) but was only half of expected. In the 20 KKW group free-living TDEE increased by ~4% (P = 0.03), which is attributed to the increased exercise energy expenditure (P = 0.001), while 24EE in the chamber decreased by ~4% (P = 0.04). Aerobic exercise at 8 KKW did not induce weight change, and there was no significant change in any component of EE. There was no significant change in energy intake for any group (P = 0.53). Conclusions: Structured aerobic exercise at a dose of 20 KKW produced less weight loss than expected possibly due to behavioral adaptations leading to reduced 24EE in a metabolic chamber without any change in energy intake. [ABSTRACT FROM AUTHOR]

Background Individuals with overweight or obesity commonly underreport energy intake (EI), but it is unknown if the tendency to underreport persists in formerly obese individuals who lose significant weight and maintain their weight loss over long periods of time. Objective Assess the accuracy of self-reported EI in successful weight loss maintainers (WLM) compared with controls of normal body weight (NC) and controls with overweight/obesity (OC). Methods Participants for this case-controlled study were recruited in 3 groups: WLM [ n = 26, BMI (in kg/m2) 24.1 ± 2.3; maintaining ≥13.6 kg weight loss for ≥1 y], NC (n = 33, BMI 22.7 ± 1.9; similar to current BMI of WLM), and OC (n = 32, BMI 34.0 ± 4.6; similar to pre–weight loss BMI of WLM). Total daily energy expenditure (TDEE) was measured over 7 d using the doubly labeled water (DLW) method, and self-reported EI was concurrently measured from 3-d diet diaries. DLW TDEE and self-reported EI were compared to determine accuracy of self-reported EI. Results WLM underreported EI (median, interquartile range) (–605, –915 to –314 kcal/d) to a greater degree than NC (–308, –471 to –68 kcal/d; P < 0.01) but not more than OC (–310, –970 to 18 kcal/d; P = 0.21). WLM also showed a greater degree of relative underreporting (–25.3%, –32.9% to –12.5%) compared with NC (–14.3%, –19.6% to –3.1%; P = 0.02) but not OC (–11.2%, –34.1% to –0.7%; P = 0.16). A greater proportion of WLM was classified as underreporters (30.8%) than NC (9.1%; P = 0.05) but not OC (28.1%; P = 1.00). Conclusions WLM underreported EI in both absolute and relative terms to a greater extent than NC but not OC. These findings call into question the accuracy of self-reported EI in WLM published in previous studies and align with recent data suggesting that WLM rely less on chronic EI restriction and more on high levels of physical activity to maintain weight loss. This trial was registered at clinicaltrials.gov as NCT03422380. [ABSTRACT FROM AUTHOR]