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RATIONALE This study determines if saliva collection procedures for the doubly labeled water (DLW) method, used for measuring total energy expenditure (TEE), are comparable to urine and plasma collection. Both the cavity ring-down spectroscopy (CRDS) and isotope ratio mass spectrometry (IRMS) analyses techniques are compared. METHODS Saliva specimens were collected from participants for the DLW method. The specimens were collected under different conditions: after consumption of tap water, after chewing gum, and during exposure to conditions of high and low relative humidity. The isotopes in saliva were compared with simultaneous plasma and urine collection. TEE calculated from saliva and analyzed using CRDS was compared to that of plasma analyzed using IRMS. RESULTS The within-individual variances were not significantly different between the saliva specimens (0.4‰) and plasma (0.3‰). After the oral dose of DLW, the saliva specimens displayed a shorter equilibration time to urine. When participants consumed 500 mL of tap water, the enrichment of saliva specimens reached a new plateau value faster than urine. Saliva collection exposed to high ambient humidity conditions was slightly less enriched as compared to low-humidity conditions while urine enrichment was unaffected. In contrast, whereas the within-individual effects of gum chewing during saliva collection on 18 O were unaffected, the abundance of 2 H in saliva was slightly lower after chewing the gum. The within-individual difference between TEE calculated from saliva and that calculated from plasma analyzed using IRMS did not differ from zero, and the standard deviation was not different from that predicted by a propagation of error analysis based on analytical error alone. CONCLUSIONS Our findings support using saliva specimens for the DLW method. The analysis of plasma and urine, however, requires reducing the memory effect resulting from contaminants. Also, it should be performed in a manner that minimizes exposure to air where specimens may be exposed to evaporation or contamination from water vapor during sampling.

We have previously reported negative energy balance and health benefits during an Alaska backcountry expeditionary hunting (ABEH) immersion in two males. The purpose of our present study was to increase the number of participants, include females, and evaluate macronutrient intake and serum lipids. Four men (age: 46 ± 6 year, BMI: 26 ± 1 kg/m2) and three women (age: 46 ± 11 year, BMI: 25 ± 3 kg/m2) were recruited. Doubly labeled water methodology and dietary recall were utilized to assess energy expenditure and energy intake, respectively. Data were collected during pre‐ and post‐ABEH visits. Body composition was measured using dual‐energy x‐ray absorptiometry and the cross‐sectional area of skeletal muscle in the upper leg (XT), and intrahepatic lipid (IHL) was determined using magnetic resonance imaging and/or spectroscopy (MRI/MRS). Blood parameters were measured by LabCorp. Paired T‐tests were used for statistical analysis. Data are reported as mean ± SD and considered significant at p, The majority of the scientific literature on exercise training has focused on standardized concepts. We assert that movement constancy of the hunter gatherer lifestyle may offer protection against metabolic abnormalities but has been largely understudied. In the context of unscripted negative energy balance, muscle preservation, and rapid improvements in metabolic biomarkers were demonstrated in both healthy females and males during an Alaskan backcountry hunting expedition.

Made available in DSpace on 2019-10-06T16:37:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Objective: To investigate the influence of changes in energy balance and body composition on the rate of weight loss throughout 1 year of Roux-en-Y gastric bypass. Methods: Variables were collected pre-, 6, and 12 months (M) post-surgery from 18 women (BMI ≥ 40 and ≤ 50 kg m−2, 20 to 45 years). Total energy expenditure (TEEm), fat-free mass (FFM), and fat mass (FM) were measured by doubly labeled water. Self-reported energy intake (EIsr) was obtained from three non-consecutive food diaries. Metabolic adaptation was assessed via deviations from TEE predictive equation, and the calculated energy intake (EIc) via the sum of TEE and change in body stores. Results: BMI significantly decreased (mean ± SD) from 45 ± 2 kg m−2 to 32 ± 3 kg m−2 at 6 M, and to 30 ± 3 kg m−2 at 12 M after surgery. The TEEm reduced significantly at both time points when compared with pre-surgery (6 M: − 612 ± 317 kcal day−1; 12 M: − 447 ± 516 kcal day−1). At 6 M, a metabolic adaptation was observed and the energy balance was − 1151 ± 195 kcal day−1, while at 12 M it was − 332 ± 158 kcal day−1. Changes in the values of TEEm were associated with changes in body weight at 12 M post-surgery. A significant underreporting was observed for EIsr (1057 ± 385 kcal day−1) vs. EIc (2083 ± 309 kcal day−1) at 12 M post-operative. Conclusion: The higher rate of weight loss at 6 M post-surgery was a response to energy imbalance, which was caused by high restriction in energy intake even with the presence of metabolic adaptation at this time. The EIsr was not sufficiently accurate to assess the energy consumption of this population. Registration of Clinical Trials (Observational Study): Brazilian Clinical Trials Registry: RBR-8k5jsj. Universal Trial Number: U1111-1206-0858. School of Pharmaceutical Sciences Sao Paulo State University – UNESP, Rodovia Araraquara Jaú, Km 01, s/n. Bairro: Campos Ville Department of Neurology University of Wisconsin – Madison, 1685 Highland Avenue, Medical Foundation Centennial Building, 7th Floor Biotechnology Center University of Wisconsin – Madison, 425 Henry Mall Street Ribeirao Preto Medical School University of Sao Paulo – USP, Avenida Bandeirantes, 3900 - Bairro: Monte Alegre Stable Isotope Center Bioscience Institute Sao Paulo State University – UNESP, Rua Prof. Dr. Antônio Celso Wagner Zanin, 250 - Bairro: Distrito de Rubião Junior Education Department Institute of Biosciences Sao Paulo State University – UNESP, Rua Prof. Dr. Antônio Celso Wagner Zanin, 250 - Bairro: Distrito de Rubião Junior School of Pharmaceutical Sciences Sao Paulo State University – UNESP, Rodovia Araraquara Jaú, Km 01, s/n. Bairro: Campos Ville Stable Isotope Center Bioscience Institute Sao Paulo State University – UNESP, Rua Prof. Dr. Antônio Celso Wagner Zanin, 250 - Bairro: Distrito de Rubião Junior Education Department Institute of Biosciences Sao Paulo State University – UNESP, Rua Prof. Dr. Antônio Celso Wagner Zanin, 250 - Bairro: Distrito de Rubião Junior

The purported healthy aspects of subsistence foods have led to the popularity of the Paleo diet. There has been very little focus, surprisingly, on health benefits derived from the nomadic nature of humans during the Paleolithic era. The purpose of our study was to examine total energy expenditure (TEE), total energy intake (TEI), body composition, blood lipids, and intrahepatic lipid in humans during a 12‐day Alaskan backcountry expeditionary hunting (ABEH) immersion. Four healthy men (age: 42 ± 3 year, BMI: 27 ± 1 kg/m2) were recruited for the study. TEE was measured using the doubly labeled water method and a food diary was utilized to assess TEI. Body composition was measured using dual energy X‐ray absorptiometry (DXA); cross‐sectional area of the thigh (XT) and intrahepatic lipid (IHL) were measured using molecular imaging. Blood samples were collected for the measurement of blood lipids. DXA, XT, IHL, and blood data were collected pre‐ and immediately post‐ABEH. Results were analyzed using paired t‐tests and considered significant at P

It is unclear whether the capabilities of recreationally active modern humans are unique due to present training practices or linked to the selection resulting from migration, escape, scavenging, and hunting and/or endurance running in early Homo. The purpose of this study was to determine upper values for total energy expenditure (TEE) and water turnover during sustained work for periods of 12-24 and 12-48 h, respectively and compare them with other species and proposed activities of early Homo. Stable isotopic water (2H218O) was used during competitions in hot environments to establish energy expenditure rates of approaching 10 times resting metabolism (RM) for 12.7 and 26.8 h, respectively. These events demonstrate pronounced hydration demands, with water output rates ranging from 25–95% of initial total body water for events lasting 12–48 h, respectively. These results provide new evidence for a high, sustained work (0.5–2 days) output and hydration demand in humans compared to other species in hot environments. Although the span for sustained metabolic activity in humans is large, it does not require elite level training status so long as adequate exogenous fuel and water are accessible. Because these values far exceed reported expectations/needs for foraging and persistence hunting in early Homo, it remains unclear if the phenomenon of the metabolic range is a modern human characteristic. While modern recreational endurance participants can demonstrate a TEE approaching 10 times RM, the rationale and need for such a high human metabolic ceiling is unclear when considering the energy demands of early Homo.

Variation of the dilution space ratio (Nd/No) between deuterium (2H) and oxygen-18 (18O) impacts the calculation of total energy expenditure (TEE) by doubly labeled water (DLW). Our aim was to examine the physiological and methodological sources of variation of Nd/Noin humans. We analyzed data from 2,297 humans (0.25-89 yr old). This included the variables Nd/No, total body water, TEE, body mass index (BMI), and percent body fat (%fat). To differentiate between physiologic and methodologic sources of variation, the urine samples from 54 subjects were divided and blinded and analyzed separately, and repeated DLW dosing was performed in an additional 55 participants after 6 mo. Sex, BMI, and %fat did not significantly affect Nd/No, for which the interindividual SD was 0.017. The measurement error from the duplicate urine sample sets was 0.010, and intraindividual SD of Nd/Noin repeats experiments was 0.013. An additional SD of 0.008 was contributed by calibration of the DLW dose water. The variation of measured Nd/Noin humans was distributed within a small range and measurement error accounted for 68% of this variation. There was no evidence that Nd/Nodiffered with respect to sex, BMI, and age between 1 and 80 yr, and thus use of a constant value is suggested to minimize the effect of stable isotope analysis error on calculation of TEE in the DLW studies in humans. Based on a review of 103 publications, the average dilution space ratio is 1.036 for individuals between 1 and 80 yr of age.

The doubly labeled water method provides an objective and accurate measure of total energy expenditure in free-living subjects and is considered the gold-standard method for this measurement. Its use, however, is limited by the need to employ isotope ratio mass spectrometry (IRMS) to obtain the high-precision isotopic abundance analyses needed to optimize the dose of expensive 18O-labeled water. Recently, cavity-ring down spectroscopy (CRDS) instruments have become commercially available and may serve as a less expensive alternative to IRMS. We compared the precision and accuracy of CRDS with those of IRMS for the measurement of total energy expenditure from urine specimens in 14 human subjects. The relative accuracy and precision (SD) for total body water was 0.5 ± 1% and for total energy expenditure was 0.5 ± 6%. The CRDS instrument displayed a memory between successive specimens of 5% for 18O and 9% for 2H. The memory necessitated carefully ordering of specimens to reduce isotopic disparity, performance of several injections of each specimen to condition the analyzer, and use of a mathematical memory correction on subsequent injections. These limited the specimen throughput to about one urine specimen per hour. CRDS provided accuracy and precision for isotope abundance measurements of urine that were comparable with those of IRMS. The memory problems were easily recognized by our experienced laboratory staff, but future efforts should be aimed at reducing the memory of the CRDS so that it would be less likely to result in poor reproducibility in laboratories using doubly labeled water for the first time. Copyright © 2010 John Wiley & Sons, Ltd.

The doubly labeled water method is commonly used to measure total energy expenditure in free-living subjects. The method, however, requires accurate and precise deuterium abundance determinations, which can be laborious. The aim of this study was to evaluate a fully automated, high-throughput, chromium reduction technique for the measurement of deuterium abundances in physiological fluids. The chromium technique was compared with an off-line zinc bomb reduction technique and also subjected to test-retest analysis. Analysis of international water standards demonstrated that the chromium technique was accurate and had a within-day precision of

to the editor: In a recent article, Guidotti et al. ([5][1]) reported that the nutritional and body adiposity status affects the dilution space ratio (Nd/No) between deuterium (2H) and 18O and validity of CO2 production (rCO2) by the doubly labeled water (DLW) method in mice. Their data disagree

Stable isotope dilution and elimination form the basis for the measurement of body composition and energy expenditure in humans. Deuterium and oxygen-18 can be used individually as tracers in water to measure total body water (TBW) and combined to measure body water turnover and carbon dioxide production. This method of indirect calorimetry provides an investigator the opportunity to track energy metabolism under free-living conditions for the study of energy requirements and weight control. Samples, typically urine, are analyzed using isotope ratio mass spectrometry, however, less expensive and easier to use instrumentation is becoming available.

Objectives: Changes in the way dietary fat is metabolized can be considered causative in obesity. The role of sedentary behavior in this defect has not been determined. We hypothesized that physical inactivity partitions dietary fats toward storage and that a resistance exercise training program mitigates storage. Design: We used bed rest, with randomization to resistance training, as a model of physical inactivity. Setting: The trial took place at the Space Clinic (Toulouse, France). Participants: A total of 18 healthy male volunteers, of mean age ± standard deviation 32.6 ± 4.0 y and body mass index 23.6 ± 0.7 kg/m2, were enrolled. Interventions: An initial 15 d of baseline data collection were followed by 3 mo of strict bed-rest alone (control group, n = 9) or with the addition of supine resistance exercise training every 3 d (exercise group, n = 9). Outcome measures: Oxidation of labeled [d31]palmitate (the main saturated fatty acid of human diet) and [1-13C]oleate (the main monounsaturated fatty acid), body composition, net substrate use, and plasma hormones and metabolites were measured. Results: Between-group comparisons showed that exercise training did not affect oxidation of both oleate (mean difference 5.6%; 95% confidence interval [95% CI], −3.3% to 14.5%; p = 0.20) and palmitate (mean difference −0.2%; 95% CI, −4.1% to 3.6%; p = 0.89). Within-group comparisons, however, showed that inactivity changed oxidation of palmitate in the control group by −11.0% (95% CI, −19.0% to −2.9%; p = 0.01) and in the exercise group by −11.3% (95% CI, −18.4% to −4.2%; p = 0.008). In contrast, bed rest did not significantly affect oleate oxidation within groups. In the control group, the mean difference in oleate oxidation was 3.2% (95% CI, −4.2% to 10.5%; p = 0.34) and 6.8% (95% CI, −1.2% to 14.7%; p = 0.08) in the exercise group. Conclusions: Independent of changes in energy balance (intake and/or output), physical inactivity decreased the oxidation of saturated but not monounsaturated dietary fat. The effect is apparently not compensated by resistance exercise training. These results suggest that Mediterranean diets should be recommended in sedentary subjects and recumbent patients., Editorial Commentary Background: Obesity is an important contributor to the burden of chronic diseases, particularly type II diabetes, cardiovascular disease, hypertension, and stroke. Being inactive is a risk factor for all of these conditions. However, the physiological effects of inactivity are not well understood. In this trial, supported by the European Space Agency, a group of researchers aimed to further understand the effects of physical inactivity on the way that fat from the diet is metabolized (i.e., broken down to generate energy). 18 healthy male volunteers were randomized into two groups, both of whom underwent 90 days of bed rest, aiming to mimic sedentary behavior. One group also received an exercise training program during the 90 days' bed rest. The researchers examined to what extent two different types of fatty acids common in the diet were metabolized over the duration of the trial: oleate (monounsaturated fat) and palmitate (saturated fat). As secondary objectives of the study, body weight, water, fat, and energy expenditure were also examined in the participants. What this trial shows: The researchers did not see any statistically significant changes between the groups—that is, participants receiving bed rest, and those receiving bed rest plus exercise training—for any of the primary or secondary outcomes, except for resting metabolic rate, which was higher in the exercise group. However, they did see physiologically relevant changes in fat metabolism of one of the fatty acids, palmitate, over the course of the trial within both groups studied. Although metabolism of oleate (monounsaturated fat) did not show significant changes over the course of the trial, metabolism of palmitate (saturated fat) dropped by nearly 10% in both groups (bed rest, and bed rest plus exercise). Strengths and limitations: The study design was appropriate to the questions being posed, and the techniques for examining fat metabolism were relevant. Although the number of participants was very small, this problem is true of many such studies due to the cost and complexity of the interventions. The model for inactivity used in this trial—90 days' bed rest—is very extreme. Very few studies of this type have been performed, with most of the evidence relating to activity and fat handling coming from training studies in otherwise sedentary people. Contribution to the evidence: It is already known that physical activity has numerous health benefits, including the prevention of obesity. This trial provides data showing that inactivity lowers the ability to metabolize fat, specifically saturated fat, from the diet, which would therefore be more likely to be stored in the body.