Doubly Labeled Water Research Articles

Measuring energy expenditure in narcolepsy using doubly-labelled water and respiration chamber calorimetry.

Hypocretin deficiency causes type 1 narcolepsy, a condition characterised by excessive daytime sleepiness, cataplexy, and fragmented nocturnal sleep. Two-thirds of people with narcolepsy are also overweight, of which half are obese. The pathophysiology behind weight gain in people with narcolepsy remains unknown. We assessed a possible decrease in energy expenditure as a cause for overweight in narcolepsy using respiration chamber calorimetry and doubly labelled water. Ten males with type I narcolepsy and nine matched (for age, sex, and BMI) healthy controls were enrolled. Subjects stayed in a respiration chamber for 24 hours. They subsequently received doubly labelled water and wore an accelerometer for two weeks to assess energy expenditure and physical activity under daily living conditions. Total daily energy expenditure, resting energy expenditure, overnight metabolic rate, physical activity level and activity-induced energy expenditure were measured. No significant differences were found in resting energy expenditure, mean 24-hour respiration chamber energy expenditure, overnight metabolic rate and activity-induced energy expenditure when comparing people with narcolepsy type 1 to controls. Physical activity was also comparable between groups. Energy expenditure in narcolepsy type 1 is similar to matched controls, suggesting comparable metabolism and physical activity rates. It remains possible that metabolic changes are most pronounced around disease onset. In addition, patients had to discontinue their medication which may have influenced the results. Still, our findings suggest that other factors may also play a role in weight gain in narcolepsy, such as differences in dietary behaviour.

Improving quality control procedures for the measurement of total daily energy expenditure using the two-point doubly labeled water method.

The precision of the doubly labeled water (DLW) method is determined by the precision and accuracy of the isotopic measurements. Quality control (QC) procedures to mitigate sample variability require additional measurements if sample duplicates differ more than a factor of instrument precision. We explored the effect of widening QC ranges on total daily energy expenditure (TDEE) determined using the two-point sampling method. We screened DLW data from 121 individuals for instances where samples were analyzed more than twice using our existing QC criteria (±2.0 per mil [δ] for 2H and ±0.5 δ for 18O). We then applied wider QC ranges for accepting duplicate measures and recalculated TDEE. Widening the 2H QC range to ±10.0 δ in samples collected on the first day (most enriched) and to ±5.0 δ in samples collected on the final day (less enriched) produced almost identical mean TDEE compared to the originally calculated TDEE (2684 ± 508 vs. 2687 ± 512 kcal/day, p= 0.40). There was a strong correlation with the originally calculated TDEE (r2=0.97, p< 0.001). Expanding the 2H QC range to ±10.0 δ for samples collected on the first day and ±5.0 δ for samples collected on the final day provides similar mean TDEE results. These findings may help DLW labs optimize QC criteria and reduce analytical costs.

Plunge-diving into dynamic body acceleration and energy expenditure in the Peruvian booby.

Daily energy expenditure (DEE) is the result of decisions on how to allocate time among activities (resting, commuting, and foraging) and the energy costs of those activities. Dynamic body acceleration (DBA), which measures acceleration associated with movement, can be used to estimate DEE. Previous studies of DBA-DEE correlations in birds occurred on species foraging below their thermoneutral zone, potentially decoupling the DBA-DEE relationship. We used doubly-labelled water (DLW) to validate the use of DBA on plunge-diving seabirds, Peruvian boobies (Sula variegata), foraging in waters above their thermoneutral zone (>19 °C). Mass-specific DEEDLW in boobies was 1.12 kJ/d/g, and higher in males than in females. DBA alone provided the best fitting model to estimate mass-specific DEEDLW compared to models partitioned per activity and time-budget models. Nonetheless, the model parametrizing activity at and away of their onshore breeding colony was the most parsimonious model (r=0.6). This r value, although high, is lower than all other avian studies, implying that temperature is not the main cause of DBA-DEE decoupling in birds. Time at the colony (∼80% of the day) was the largest contributor to DEE as it was the most time-consuming activity and involved nest defense. However, foraging was the most power-consuming activity (4.6 times higher activity-specific metabolic rate than resting at the colony), and commuting-flight was higher than in other gliding seabirds. In short, DBA alone can act as a proxy for DEE, opening avenues to measure the conservation energetics of this seabird in the rapidly-changing Peruvian Humboldt Current System.

Time-energy budgets outperform dynamic body acceleration in predicting daily energy expenditure in kittiwakes, and estimate a very low cost of gliding flight relative to flapping flight.

Energy is a common currency for any living organism, yet estimating energy expenditure in wild animals is challenging. Accelerometers are commonly used to estimate energy expenditure, via a dynamic body acceleration (DBA) or time-energy budget approach. The dynamic body acceleration approach estimates energy expenditure directly from acceleration but may lead to erroneous estimates during inactivity when acceleration is zero but energy expenditure is not. The time-energy budget approach uses accelerometers and other data streams to assign a behaviour to each time step, and then calculates energy expenditure based on activity-specific metabolic rates assigned to each behaviour. Here, used GPS-accelerometry in breeding black-legged kittiwakes (Rissa tridactyla, n=80) to calculate DBA and time-energy budgets derived from simple biologging metrics (speed, wing beat frequency, GPS position). We then compared these two approaches to estimates of energy expenditure from doubly-labelled water. Energy expenditure estimated from DLW correlated with DBA, but the best model to estimate energy expenditure was based on time-energy budgets. Energy costs of flapping flight were higher than all other kittiwake behaviours (5.54 x basal metabolic rate, BMR). Energetic costs of gliding flight (0.80 x BMR) were the lowest of all behaviours, and equivalent to the cost of resting at the colony. DEE for our birds estimated from our calibration coefficients are similar to DEE for our birds estimated with the model coefficient published using different methods. We conclude that once calibrated with DLW, GPS-accelerometry provides a simple method for measuring energy expenditure in wild kittiwakes based on time-energy budgets.

Factors associated with water consumption measured using the stable isotope techniques among Japanese adults: a cross-sectional study.

While some dietary guidelines have established daily water requirements for adults, those for older adults are not well defined. Factors associated with water turnover (WT), indicating water requirements and preformed water (PW), referring to fluids consumed from food and beverages, remain poorly understood. Therefore, we aimed to investigate these factors in Japanese adults. This cross-sectional study included 57 participants aged 54-85 years, living in Fukuoka City, Japan. The WT and PW were measured using the doubly labelled water (DLW) methods from August 2015 to September 2015. Dietary intake and physical activity were evaluated using a 3-day dietary record (DR) and a validated triaxial accelerometer, respectively. Fasting blood and urine samples, as well as environmental conditions, were assessed using a validated technique. We evaluated the variables for predicting water consumption by using a multivariate generalised linear model, with forward stepwise selection using these covariates. The median WT and PW were 2842 ml/day and 2227 ml/day, respectively. In the multivariate model, WT (R2 = 0.629) and PW (R2 = 0.621) were moderately predicted by variables such as sex, body weight, moderate-to-vigorous physical activity, water consumption estimated by DR, urinary aldosterone and osmolality, creatinine clearance and wet-bulb globe temperature. The PW estimates from DR were ~40% lower than those from DLW method, despite a significant correlation between the values. WT and PW are associated not only with lifestyle and environmental factors but also with urinary markers and kidney function. These findings provide useful insights into the differences in each individual's water requirement.

The Physiological Consequences of and Recovery following the Australian Special Forces Selection Course.

This study aimed to determine the energy requirements, physiological consequences, and recovery rate from the Australian Special Forces Selection Course. Ninety-three male soldiers (mean ± SD, 28.1 ± 3.6 y, 1.81 ± 0.1 m, 85.1 ± 8.1 kg) volunteered for this study. Body composition via dual-energy x-ray absorptiometry, hormones and resting metabolic rate were assessed before, immediately after, and at one, three, five, and eight weeks post-course. Energy expenditure, assessed via doubly-labelled water during the first 10 days of the course significantly exceeded energy intake (expenditure: 7680 ± 1095 kcal.d-1, intake: 3859 ± 704 kcal.d-1). Body mass (△ -6.8 ± 1.9 kg, p<0.01), fat mass (△ -4.2 ± 1.0 kg, p<0.0001) and lean mass (△ -3.0 ± 1.7 kg, p<0.0001) were significantly reduced in response to the course and returned to baseline 1-3 weeks post-course. Total testosterone, free testosterone, free triiodothyronine, free thyroxine and insulin like growth factor-1 significantly (p<0.001) declined following the course, while cortisol and sex hormone binding globulin increased (p<0.001). All hormones, except insulin like growth factor-1, returned to baseline concentrations within 1-3 weeks post-course. Resting metabolic rate decreased (p<0.01) in response to the course, and subsequently rebounded above baseline levels at one week post-course. The Special Forces Selection Course involved high energy output and a substantial caloric deficit, resulting in body mass loss and significant hormonal disruption that took weeks to recover. These results highlight the energy requirements, physiological consequences, and recovery processes from the Australian Special Forces Selection Course.

Validation of an web-based dietary assessment tool (RiksmatenFlex) against doubly labelled water and 24 h dietary recalls in pregnant women

IntroductionDigital technologies have enabled new possibilities to assess dietary intake and have shown promise in terms of decreased participant burden, improved accuracy and lower costs. However, their potential and validity in pregnant populations are scarcely explored.ObjectivesThis study aimed to (a) validate energy intakes obtained from a web-based dietary recall method developed for national surveys (RiksmatenFlex) against total energy expenditure (TEE) by means of the doubly labelled water (DLW) method, and (b) to compare intakes of macronutrients, key unhealthy and healthy foods as well as adherence to food-based dietary guidelines between RiksmatenFlex and repeated 24 h telephone dietary recalls in healthy Swedish pregnant women.MethodsThis study was conducted as a nested validation within the HealthyMoms trial. Intakes of foods, macronutrients and energy were assessed during three days through RiksmatenFlex and 24 h telephone dietary recalls, and Swedish Healthy Eating Index (SHEI) scores were also calculated for both methods (n = 52). For 24 women, TEE was also assessed through the DLW method. Paired Samples T-tests and Wilcoxon Signed Ranks Tests were used to identify differences between means for foods, macronutrients, energy and SHEI scores. Pearson correlation coefficient or Spearman’s rho were performed to identify relationships between variables. To compare energy intake (RiksmatenFlex) with TEE (DLW method) and 24 h telephone dietary recalls, Bland and Altman plots were constructed.ResultsAverage energy intake from RiksmatenFlex (10,015 [SD 2004] kJ) was not statistically different from TEE (10,252 [SD 1197] kJ) (p = 0.596) (mean difference: -237 kJ/24 h). Correspondingly, there were small mean differences between average intakes of key unhealthy and healthy foods and average SHEI scores between RiksmatenFlex and 24 h telephone dietary recalls. However, the Bland and Altman plots showed wide limits of agreement for all dietary variables (e.g., for energy intake using RiksmatenFlex versus TEE: ±4239 kJ/24 h). High correlations between the investigated dietary variables for the two dietary methods were observed (r = 0.751 to 0.931; all p < 0.001).ConclusionRiksmatenFlex captured average intakes of energy, unhealthy and healthy food groups and adherence to food-based dietary guidelines in a comparable way to 24 h telephone dietary recalls and the DLW method. Our results support the validity of RiksmatenFlex as a web-based dietary assessment method for future use in pregnancy for intervention studies and national dietary surveys.

Preliminary field validity of ActiGraph-based energy expenditure estimation in wheelchair users with spinal cord injury.

Cross-sectional validation study. To develop a raw acceleration signal-based random forest (RF) model for predicting total energy expenditure (TEE) in manual wheelchair users (MWUs) and evaluate the preliminary field validity of this new model, along with four existing models published in prior literature, using the Doubly Labeled Water (DLW) method. General community and research institution in Pittsburgh, USA. A total of 78 participants' data from two previous studies were used to develop the new RF model. A seven-day cross-sectional study was conducted to collect participants' free-living physical activity and TEE data, resting metabolic rate, demographics, and anthropometrics. Ten MWUs with spinal cord injury (SCI) completed the study, with seven participants having valid data for evaluating the preliminary field validity of the five models. The RF model achieved a mean absolute error (MAE) of 0.59 ± 0.60 kcal/min and a mean absolute percentage error (MAPE) of 23.6% ± 24.3% on the validation set. For preliminary field validation, the five assessed models yielded MAE from 136 kcal/day to 1141 kcal/day and MAPE from 6.1% to 50.2%. The model developed by Nightingale et al. in 2015 achieved the best performance (MAE: 136 ± 96 kcal/day, MAPE: 6.1% ± 4.7%), while the RF model achieved comparable performance (MAE: 167 ± 99 kcal/day, MAPE: 7.4% ± 5.1%). Two existing models and our newly developed RF model showed good preliminary field validity for assessing TEE in MWUs with SCI and the potential to detect lifestyle change in this population. Future large-scale field validation studies and model iteration are recommended.

Predictors of Water Turnover in Older Adults: A Doubly Labeled Water- and Triaxial Accelerometer-Based Study

BackgroundWater 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. ObjectivesThe 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. MethodsThis 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. ResultsWT 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. ConclusionsOur results confirmed that age, sex, weight, FFM, TEE, and PAL are the potential predictors of WT in older Japanese adults aged ≥65 y.

Links between energy budgets, somatic condition, and life history reveal heterogeneous energy management tactics in a group-living mesocarnivore

BackgroundOptimal management of voluntary energy expenditure is crucial to the survival and reproductive success of wild animals. Nevertheless, a growing appreciation of inter-individual variation in the internal state driving movement suggests that individuals may follow different, yet equally optimal tactics under the same environmental conditions. However, few studies in wild populations have investigated the occurrence and demographic context of different contemporaneous energetic expenditure tactics. Here, we explore this neglected aspect of energy budgeting in order to determine the effect of life-history traits such as age and reproductive status on the co-occurrence of different energy-budgeting tactics in wild populations.MethodsWe investigated inter-individual heterogeneity in energy expenditure within a wild population of European badgers (Meles meles) by quantifying individual overall dynamic body acceleration (ODBA, from tri-axial accelerometry collars) and total daily energy expenditure (DEE, from doubly-labelled water) during 6–9 day deployments and dosing periods over six different seasons (spring, summer, and autumn) in 2018–2019. We obtained ODBA values for 41 deployments (24 unique badgers) and DEE measurements for 41 dosings (22 unique badgers). We then evaluated correlations between these energetic metrics and computed individual ratios of ODBA/DEE as a proxy for the proportion of total energy spent on activity. We measured the impact of alternative ODBA/DEE ratios on body condition, and use survival models constructed using 29 years of demographic data from the same population to situate body-condition changes in the context of age and reproductive status.ResultsBoth ODBA and DEE were highly variable between individuals and exhibited season-specific relationships with individual body condition and life-history factors. DEE scaled allometrically with body weight, but only in summer and autumn; post-reproductive female badgers were lighter than other badgers during the spring but expended on average 350 kJ/day more than predicted from allometric scaling. Older badgers expended significantly less energy on movement during the summer than did younger adults. The ratio of ODBA to DEE (OD) provides a measure of proportional investment into movement. This ratio correlated more significantly with next-season body condition than either energetic metric did independently. However, the majority of individuals with high OD ratios were either younger badgers or reproductive females, for which lower body condition typically presented less of a mortality risk in previous analyses of this population.ConclusionsWithin a single population under the same environmental conditions, we found wide inter-individual variation in both mechanical and total energy expenditure. The adoption of different tactics aligns with relationships between life-history parameters and mortality risk previously studied within the population. Crucially, younger badgers and reproductive females appeared able to tolerate energy expenditure tactics that depleted their body condition more than other badgers. These findings provide a mechanism by which differences in individual energetic context set by life history can maintain heterogeneity in wild populations, providing a wide range of potential energetic tactics under changing environmental conditions.

Energy expenditure in healthy pregnant women: a systematic review.

Since pregnancy is a decisive period for women and children in terms of future health, it is very important to determine changes in energy expenditure and requirements. However, there is no reference method to determine the energy expenditure as there are many factors that change maternal energy homeostasis during this period. This review aims to evaluate the changes in energy expenditure during pregnancy and the effects of these changes on maternal weight gain, as well as the methods used to determine energy expenditure. Google Scholar, PubMed, ScienceDirect, Cochrane Library, and Wiley Online Library databases were searched to determine studies on energy expenditure during pregnancy between 2010 and 2022. Of the 2095 articles initially identified, 20 met the inclusion criteria for this review. Two independent reviewers selected and extracted data from those articles. The articles reviewed show that prepregnancy body mass index, gestational weight gain, changes in fat mass, and lean body mass influence energy expenditure during pregnancy. Doubly-labeled water and indirect calorimetric methods are considered reference methods for determining energy expenditure in pregnancy. Indirect calorimetric methods, when used together with body weight and physical activity measurements, allow an accurate estimation of resting energy expenditure and energy requirements for pregnant women. Metabolic Holter or accelerometers are valid methods for determining activity energy expenditure in pregnant women and are suitable for use during activity. Resting energy expenditure and activity energy expenditure should be carefully monitored and measured by valid methods to achieve the correct energy intake targets during pregnancy. The existing equations used in determining energy expenditure should be developed for a more accurate estimation of energy expenditure during pregnancy, or new pregnancy-specific equations should be derived.

Determinant of factors associated with water requirement measured using the doubly labelled water method among older Japanese adults.

Water is an essential nutrient for all organisms and is important for maintaining life and health. We aimed to develop a biomarker-calibrated equation for predicting water turnover (WT) and pre-formed water (PW) using the doubly labelled water (DLW) method. Cross-sectional study. General older population from the Kyoto-Kameoka Study, Japan. The 141 participants aged ≥ 65 years were divided into a model developing (n 71) and a validation cohort group (n 70) using a random number generation. WT and PW was measured using the DLW method in May-June of 2012. In developing the cohort, equations for predicting WT and PW were developed by multivariate stepwise regression using all data from the questionnaires in the Kyoto-Kameoka study (including factors such as dietary intake and personal characteristics). WT and PW measured using the DLW method were compared with the estimates from the regression equations developed using the Wilcoxon signed-rank test and correlation analysis in validation cohort. The median WT and PW for 141 participants were 2·81 and 2·28 l/d, respectively. In the multivariate model, WT (R2 = 0·652) and PW (R2 = 0·623) were moderately predicted using variables, such as height, weight and fluid intake from beverages based on questionnaire data. WT (r = 0·527) and PW (r = 0·477) predicted that using this model was positively correlated with the values measured by the DLW method. Our results showed factors associated with water requirement and indicated a methodological approach of calibrating the self-reported dietary intake data using biomarkers of water consumption.

Oral Motor Impairments Contribute to Weight Status of Adults with Severe Cerebral Palsy.

Adults with severe cerebral palsy (CP) are susceptible to malnutrition and metabolic disorders due to limited daily physical activity and challenges related to eating. We hypothesized that the condition of being underweight arises from inadequate energy intake due to difficulties in eating, rather than heightened total energy expenditure or an elevated resting metabolic rate. The present study encompassed 17 adults with severe CP (classified as GMFSC III-V). Energy intake, utilization, and expenditure were gauged via thorough dietary recordings and double-labeled water (DLW) analyses. Resting metabolic rates were assessed through indirect calorimetry, and metabolic health was investigated via blood samples. Oral motor function, eating assessment during meals, and weight fluctuations throughout the experimental period were also evaluated. We found significant correlations between weight, oral impairments (p < 0.01), and eating difficulties (p < 0.05). While total energy expenditure and daily consumption were similar between underweight (UW) and overweight (OW) individuals, significant variability in both expenditure and intake was evident within the UW group. Particularly, those with lower BMIs experienced heightened mealtime impairments and complications. Our present findings indicate that eating difficulties are the central concern for UW status in this population.

Determining energy expenditure in a large seabird using accelerometry.

The trade off between energy gained and expended is the foundation of understanding how, why and when animals perform any activity. Based on the concept that animal movements have an energetic cost, accelerometry is increasingly being used to estimate energy expenditure. However, validation of accelerometry as an accurate proxy for field metabolic rate in free-ranging species is limited. In the present study, Australasian gannets (Morus serrator) from the Pope's Eye colony (38°16'42″S 144°41'48″E), south-eastern Australia, were equipped with GPS and tri-axial accelerometers and dosed with doubly labelled water (DLW) to measure energy expenditure during normal behaviour for 3-5 days. The correlation between daily energy expenditure from the DLW and vectorial dynamic body acceleration (VeDBA) was high for both a simple correlation and activity-specific approaches (R2=0.75 and 0.80, respectively). Varying degrees of success were observed for estimating at-sea metabolic rate from accelerometry when removing time on land using published energy expenditure constants (R2=0.02) or activity-specific approaches (R2=0.42). The predictive capacity of energy expenditure models for total and at-sea periods was improved by the addition of total distance travelled and proportion of the sampling period spent at sea during the night, respectively (R2=0.61-0.82). These results indicate that accelerometry can be used to estimate daily energy expenditure in free-ranging gannets and its accuracy may depend on the inclusion of movement parameters not detected by accelerometry.

Distribution of water turnover by sex and age as estimated by prediction equation in Japanese adolescents and adults: the 2016 National Health and Nutrition Survey, Japan

BackgroundAlthough water is essential to the maintenance of health and life, standard values for human water requirements are yet to be determined. This study aimed to evaluate the distribution of water turnover (WT) according to sex and age, estimated using a prediction equation, in Japanese adolescents and adults.MethodsThis cross-sectional study used data from the 2016 National Health and Nutrition Survey, Japan. Data were obtained from electronically available aggregated reports in the survey’s official website. Participants aged between 15 and 80 years (10,546 men, 12,355 women) were selected using stratified random sampling. WT was calculated considering lifestyle and environmental factors, and using an equation (coefficient of determination = 0.471) previously developed by the international doubly labelled water (DLW) database group. As data on physical activity levels (PAL) were not collected in the survey, we used two evaluation methods: (1) energy intake assessed by dietary records and (2) total energy expenditure measured by the DLW method reported in previous Japanese studies, divided by basal metabolic rate predicted using the equation. We evaluated the relationship between WT and age using a restricted cubic spline model.ResultsThe average WT for the 15–19, 20–29, 30–39, 40–49, 50–59, 60–69, and ≥ 70 years was 3291, 3151, 3213, 3243, 3205, 3104, and 2790 ml/day, respectively in men, and 2641, 2594, 2741, 2739, 2753, 2707, and 2482 ml/day, respectively in women. In the spline model, WT showed an inverse association with age in men older than 50 years, whereas women showed a reverse U-shaped relationship between WT and age (p for non-linearity < 0.001), although results differed with body weight adjustment. Similar results were found for both PAL evaluation methods, and the range of WT per body weight was 45–56 ml/day for both sexes.ConclusionsWe determined the standard values of WT in Japanese population using a prediction equation and national large-scale survey data. These findings may be useful for setting water requirements for dietary guidelines in future.

Assessing daily energy intake in adult women: validity of a food-recognition mobile application compared to doubly labelled water.

Accurate dietary assessment is crucial for nutrition and health research. Traditional methods, such as food records, food frequency questionnaires, and 24-hour dietary recalls (24HR), have limitations, such as the need for trained interviewers, time-consuming procedures, and inaccuracies in estimations. Novel technologies, such as image-based dietary assessment apps, have been developed to overcome these limitations. SNAQ is a novel image-based food-recognition app which, based on computer vision, assesses food type and volume, and provides nutritional information about dietary intake. This cross-sectional observational study aimed to investigate the validity of SNAQ as a dietary assessment tool for measuring energy and macronutrient intake in adult women with normal body weight (n = 30), compared to doubly labeled water (DLW), a reference method for total daily energy expenditure (TDEE). Energy intake was also estimated using a one-day 24HR for direct comparison. Bland-Altman plots, paired difference tests, and Pearson's correlation coefficient were used to assess agreement and relationships between the methods. SNAQ showed a slightly higher agreement (bias = -329.6 kcal/day) with DLW for total daily energy intake (TDEI) compared to 24HR (bias = -543.0 kcal/day). While both SNAQ and 24HR tended to underestimate TDEI, only 24HR significantly differed from DLW in this regard (p < 0.001). There was no significant relationship between estimated TDEI and TDEE using SNAQ (R2 = 27%, p = 0.50) or 24HR (R2 = 34%, p = 0.20) and there were no significant differences in energy and macronutrient intake estimates between SNAQ and 24HR (Δ = 213.4 kcal/day). In conclusion, these results indicate that SNAQ provides a closer representation of energy intake in adult women with normal body weight than 24HR when compared to DLW, but no relationship was found between the energy estimates of DLW and of the two dietary assessment tools. Further research is needed to determine the clinical relevance and support the implementation of SNAQ in research and clinical settings. Clinical trial registration: This study is registered on ClinicalTrials.gov with the unique identifier NCT04600596 (https://clinicaltrials.gov/ct2/show/NCT04600596).

Validation of Total Water Intake from the Automated Self-Administered 24-h Recall, 4-d Food Records, and a Food Frequency Questionnaire Using Doubly Labeled Water

Although prior evidence indicates that water intake is important for health, the ability to accurately measure community-dwelling intake is limited. Only a few studies have evaluated self-reported water intake against an objective recovery biomarker. The aim was to compare preformed water intakes (all sources including food) by multiple Automated Self-Administered 24-h recalls (ASA24s), food frequency questionnaires (FFQs), and 4-d food records (4DFRs) against a recovery biomarker, doubly labeled water (DLW), to assess measurement error. Over 1 y, 1082 women and men (50%), aged 50 to 74 y, were asked to complete 6 ASA24s, 2 FFQs, 2 unweighted 4DFRs, and an administration of DLW (n = 686). Geometric means of water intake by self-report tools were compared with DLW. Attenuation factors and correlation coefficients between self-reported and the recovery biomarker (DLW) were estimated. Mean water intakes by DLW were 2777 mL/d (interquartile range, 2350 to 3331) in women and 3243 mL/d (interquartile range, 2720 to 3838) in men. Compared with DLW, water intake was underestimated by 18% to 31% on ASA24s and 43% to 44% on 4DFRs. Estimated geometric means from FFQs differed from DLW by -1% to +13%. For a single ASA24, FFQ, and 4DFR, attenuation factors were 0.28, 0.27, and 0.32 and correlation coefficients were 0.46, 0.48, and 0.49, respectively. Repeated use of 6 ASA24s, 2 FFQs, and 2 4DFRs improved attenuation factors to 0.43, 0.32, and 0.39 and correlation coefficients to 0.58, 0.53, and 0.54, respectively. FFQs may better estimate population means for usual water intake compared with ASA24 and 4DFR. Similar attenuation factors and correlation coefficients across all self-report tools indicate that researchers have 3 feasible options if the goal is understanding intake-disease relationships. The findings are useful for planning future nutrition studies that set policy priorities for populations and to understand the health impact of water. This trial was registered at clinicaltrials.gov as NCT03268577.

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.

Metabolizable Energy Content of Breastmilk Supports Normal Growth in Exclusively Breastfed Icelandic Infants to Age 6 Months

BackgroundNeither the global population nor individual countries have reached the World Health Organization (WHO) target of ≥50% of infants exclusively breastfed (EBF) until 6 mo. This may partly be because of the perceptions of insufficient milk and energy supply to meet rapid growth and development needs. ObjectivesIn a longitudinal observational study, we aimed to determine whether breastmilk energy content is sufficient to support growth during EBF until 6 mo. MethodsA sample of 27 EBF infants was dosed with doubly labeled water (DLW) at 5.6 mo to measure body composition, breastmilk intake, energy intake, and the metabolizable energy (ME) content of their mother’s breastmilk over the following week. Z-scores were calculated for anthropometry using WHO reference data and for fat-free mass (FFM) and fat mass (FM) using United Kingdom reference data. ResultsAnthropometric z-scores from birth indicated normal weight and length growth patterns. At ∼6 mo, the mean ± standard deviation (SD) FFM z-score was 0.22 ± 1.07, and the FM z-score was 0.78 ± 0.70, significantly >0. In the 22 infants with acceptable data, the mean ± SD measured intake of breastmilk was 983 ± 170 g/d and of energy, 318 ± 60 kJ/kg/d, equivalent to 75.9 ± 14.3 kcal/kg/d. The mean ME content of breastmilk was 2.61 kJ/g [standard error (SE) 0.1], equivalent to 0.62 kcal/g (SE 0.02). Mothers were positive toward breastfeeding, on paid maternity leave (planned mean 10 mo), and many (56%) had received specialized breastfeeding support. ConclusionsThe evidence from this study confirms that when mothers are motivated and supported without economic restraints, breastmilk intake and the energy supplied by breastmilk to EBF infants at 6 mo of age is sufficient to support normal growth patterns. There was no evidence of constraint on FFM, and other studies show that high FM in EBF infants is likely to be transient. These data further support the recommendation for EBF ≤6 mo of age for body composition.This trial was registered at clinicaltrials.gov as NCT02586571.

Combining accelerometry with allometry for estimating daily energy expenditure in joules when in-lab calibration is unavailable

BackgroundAll behaviour requires energy, and measuring energy expenditure in standard units (joules) is key to linking behaviour to ecological processes. Animal-borne accelerometers are commonly used to infer proxies of energy expenditure, termed ‘dynamic body acceleration’ (DBA). However, converting acceleration proxies (m/s2) to standard units (watts) involves costly in-lab respirometry measurements, and there is a lack of viable substitutes for empirical calibration relationships when these are unavailable.MethodsWe used past allometric work quantifying energy expenditure during resting and locomotion as a function of body mass to calibrate DBA. We used the resulting ‘power calibration equation’ to estimate daily energy expenditure (DEE) using two models: (1) locomotion data-based linear calibration applied to the waking period, and Kleiber’s law applied to the sleeping period (ACTIWAKE), and (2) locomotion and resting data-based linear calibration applied to the 24-h period (ACTIREST24). Since both models require locomotion speed information, we developed an algorithm to estimate speed from accelerometer, gyroscope, and behavioural annotation data. We applied these methods to estimate DEE in free-ranging meerkats (Suricata suricatta), and compared model estimates with published DEE measurements made using doubly labelled water (DLW) on the same meerkat population.ResultsACTIWAKE’s DEE estimates did not differ significantly from DLW (t(19) = − 1.25; P = 0.22), while ACTIREST24’s estimates did (t(19) = − 2.38; P = 0.028). Both models underestimated DEE compared to DLW: ACTIWAKE by 14% and ACTIREST by 26%. The inter-individual spread in model estimates of DEE (s.d. 1–2% of mean) was lower than that in DLW (s.d. 33% of mean).ConclusionsWe found that linear locomotion-based calibration applied to the waking period, and a ‘flat’ resting metabolic rate applied to the sleeping period can provide realistic joule estimates of DEE in terrestrial mammals. The underestimation and lower spread in model estimates compared to DLW likely arise because the accelerometer only captures movement-related energy expenditure, whereas DLW is an integrated measure. Our study offers new tools to incorporate body mass (through allometry), and changes in behavioural time budgets and intra-behaviour changes in intensity (through DBA) in acceleration-based field assessments of daily energy expenditure.