The doubly labeled water method produces highly reproducible longitudinal results in nutrition studies

Energy expenditure during physical work in cold environments: physiology and performance considerations for military service members

Effective execution of military missions in cold environments requires highly trained, well-equipped, and operationally ready service members. Understanding the metabolic energetic demands of performing physical work in extreme cold conditions is critical for individual medical readiness of service members. In this narrative review, we describe 1) the extreme energy costs of performing militarily relevant physical work in cold environments, 2) key factors specific to cold environments that explain these additional energy costs, 3) additional environmental factors that modulate the metabolic burden, 4) medical readiness consequences associated with these circumstances, and 5) potential countermeasures to be developed to aid future military personnel. Key characteristics of the cold operational environment that cause excessive energy expenditure in military personnel include thermoregulatory mechanisms, winter apparel, inspiration of cold air, inclement weather, and activities specific to cold weather. The combination of cold temperatures with other environmental stressors, including altitude, wind, and wet environments, exacerbates the overall metabolic strain on military service members. The high energy cost of working in these environments increases the risk of undesirable consequences, including negative energy balance, dehydration, and subsequent decrements in physical and cognitive performance. Such consequences may be mitigated by the application of enhanced clothing and equipment design, wearable technologies for biomechanical assistance and localized heating, thermogenic pharmaceuticals, and cold habituation and training guidance. Altogether, the reduction in energy expenditure of modern military personnel during physical work in cold environments would promote desirable operational outcomes and optimize the health and performance of service members.

[Determination of the missrreporting of energy intake by Goldberg and Black in the FACSA cohort. Pilot study.]

Introduction

Introduction: the Goldberg and Black method estimates dietary underreporting in epidemiological food consumption studies. This method compares the self-reported energy intake of the subjects with the estimate of their total energy expenditure. Objective: to evaluate underreporting and overreporting at individual and group levels in Health Sciences students. Material and methods: the study was cross-sectional and prospective; the participants recorded their food consumption through two dietary records, one on the weekend and the other on the weekdays. They previously answered to sign an informed consent letter, after which the physical activity questionnaire (IPAQ) they were also weighed and measured, and then the basal metabolic rate (BMR) was estimated, It calculated later the declared intake (EI)/BMR ratio, and finally, the cut-off points to determine under-declarers, over declarators and plausible declarators. Results: we found 14.81 % underreporting at the individual level and 44.44 % at the group level. The subjects with a higher BMI and those who performed strenuous physical activity were the ones who underreported the most. The subjects underreported performed moderate and severe physical activity at the group level. Conclusions: it is crucial to carry out this methodology to verify the results of dietary evaluation since underreporting affects the estimation of nutrient intake and can alter the associations between diet and diseases in epidemiological studies.

Application of the Bland-Altman and Receiver Operating Characteristic (ROC) Approaches to Study Isotope Effects in Gas Chromatography-Mass Spectrometry Analysis of Human Plasma, Serum and Urine Samples

The Bland-Altman approach is one of the most widely used mathematical approaches for method comparison and analytical agreement. This work describes, for the first time, the application of Bland-Altman to study 14N/15N and 1H/2H (D) chromatographic isotope effects of endogenous analytes of the L-arginine/nitric oxide pathway in human plasma, serum and urine samples in GC-MS. The investigated analytes included arginine, asymmetric dimethylarginine, dimethylamine, nitrite, nitrate and creatinine. There was a close correlation between the percentage difference of the retention times of the isotopologs of the Bland-Altman approach and the area under the curve (AUC) values of the receiver operating characteristic (ROC) approach (r = 0.8619, p = 0.0047). The results of the study suggest that the chromatographic isotope effects in GC-MS result from differences in the interaction strengths of H/D isotopes in the derivatives with the hydrophobic stationary phase of the GC column. D atoms attenuate the interaction of the skeleton of the molecules with the lipophilic GC stationary phase. Differences in isotope effects in plasma or serum and urine in GC-MS are suggested to be due to a kind of matrix effect, and this remains to be investigated in forthcoming studies using Bland-Altman and ROC approaches.

Continuous glucose monitoring for automatic real-time assessment of eating events and nutrition: a scoping review

Background

Accurate dietary assessment remains a challenge, particularly in free-living settings. Continuous glucose monitoring (CGM) shows promise in optimizing the assessment and monitoring of ingestive activity (IA, i.e., consumption of calorie-containing foods/beverages), and it might enable administering dietary Just-In-Time Adaptive Interventions (JITAIs).

Objective

In a scoping review, we aimed to answer the following questions: (1) Which CGM approaches to automatically detect IA in (near-)real-time have been investigated? (2) How accurate are these approaches? (3) Can they be used in the context of JITAIs?

Methods

We systematically searched four databases until October 2023 and included publications in English or German that used CGM-based approaches for human (all ages) IA detection. Eligible publications included a ground-truth method as a comparator. We synthesized the evidence qualitatively and critically appraised publication quality.

Results

Of 1,561 potentially relevant publications identified, 19 publications (17 studies, total N = 311; for 2 studies, 2 publications each were relevant) were included. Most publications included individuals with diabetes, often using meal announcements and/or insulin boluses accompanying meals. Inpatient and free-living settings were used. CGM-only approaches and CGM combined with additional inputs were deployed. A broad range of algorithms was tested. Performance varied among the reviewed methods, ranging from unsatisfactory to excellent (e.g., 21% vs. 100% sensitivity). Detection times ranged from 9.0 to 45.0 min.

Conclusion

Several CGM-based approaches are promising for automatically detecting IA. However, response times need to be faster to enable JITAIs aimed at impacting acute IA. Methodological issues and overall heterogeneity among articles prevent recommending one single approach; specific cases will dictate the most suitable approach.

Diet composition, adherence to calorie restriction, and cardiometabolic disease risk modification

Calorie restriction (CR) is a promising approach for attenuating the risk of age-related disease. However, the role of diet composition on adherence to CR and the effects of CR on cardiometabolic markers of healthspan remains unknown. We used the Geometric Framework for Nutrition approach to examine the association between macronutrient composition and CR adherence during the 2-year CALERIE trial. Adult participants without obesity were randomized to a 25% CR intervention or an ad libitum intake control. Correlations of cardiometabolic risk factors with macronutrient composition and standard dietary pattern indices [Alternate Mediterranean Diet Index (aMED), Dietary Inflammatory Index (DII), and Healthy Eating Index (HEI)] were also evaluated by Spearman's correlation at each time point. The mean age was 38.1 ± 7.2 years at baseline and the mean BMI was 25.1 ± 1.7. The study population was 70% female. The CR group, but not the control, consumed a higher percentage reported energy intake from protein and carbohydrate and lower fat at 12 months compared to baseline; comparable results were observed at 24 months. Protein in the background of higher carbohydrate intake was associated with greater adherence at 24 months. There was no correlation between macronutrient composition and cardiometabolic risk factors in the CR group. However, statistically significant correlations were observed for the DII and HEI. These findings suggest that individual self-selected macronutrients have an interactive but not independent role in CR adherence. Additional research is required to examine the impact of varying macronutrient compositions on adherence to CR and resultant modification to cardiometabolic risk factors.

Effects of Structured Supervised Exercise Training or Motivational Counseling on Pregnant Women's Physical Activity Level: FitMum - Randomized Controlled Trial

Background

Physical activity (PA) during pregnancy is an effective and safe way to improve maternal health in uncomplicated pregnancies. However, compliance with PA recommendations remains low among pregnant women.

Objective

The purpose of this study was to evaluate the effects of offering structured supervised exercise training (EXE) or motivational counseling on PA (MOT) during pregnancy on moderate-to-vigorous intensity physical activity (MVPA) level. Additionally, complementary measures of PA using the Pregnancy Physical Activity Questionnaire (PPAQ) and gold standard doubly labeled water (DLW) technique were investigated. The hypotheses were that both EXE and MOT would increase MVPA in pregnancy compared with standard care (CON) and that EXE would be more effective than MOT. In addition, the association between MVPA and the number of sessions attended was explored.

Methods

A randomized controlled trial included 220 healthy, inactive pregnant women with a median gestational age of 12.9 (IQR 9.4-13.9) weeks. A total of 219 women were randomized to CON (45/219), EXE (87/219), or MOT (87/219). The primary outcome was MVPA (minutes per week) from randomization to the 29th gestational week obtained by a wrist-worn commercial activity tracker (Vivosport, Garmin International). PA was measured by the activity tracker throughout pregnancy, PPAQ, and DLW. The primary outcome analysis was performed as an analysis of covariance model adjusting for baseline PA.

Results

The average MVPA (minutes per week) from randomization to the 29th gestational week was 33 (95% CI 18 to 47) in CON, 50 (95% CI 39 to 60) in EXE, and 40 (95% CI 30 to 51) in MOT. When adjusted for baseline MVPA, participants in EXE performed 20 (95% CI 4 to 36) minutes per week more MVPA than participants in CON (P=.02). MOT was not more effective than CON; EXE and MOT also did not differ. MVPA was positively associated with the number of exercise sessions attended in EXE from randomization to delivery (P=.04). Attendance was higher for online (due to COVID-19 restrictions) compared with physical exercise training (P=.03). Adverse events and serious adverse events did not differ between groups.

Conclusions

Offering EXE was more effective than CON to increase MVPA among pregnant women, whereas offering MOT was not. MVPA in the intervention groups did not reach the recommended level in pregnancy. Changing the intervention to online due to COVID-19 restrictions did not affect MVPA level but increased exercise participation.

Trial Registration

ClinicalTrials.gov NCT03679130; https://clinicaltrials.gov/ct2/show/NCT03679130

International Registered Report Identifier (IRRID)

RR2-10.1136/bmjopen-2020-043671

Fetal programming of human energy homeostasis brain networks: Issues and considerations

In this paper, we present a transdisciplinary framework and testable hypotheses regarding the process of fetal programming of energy homeostasis brain circuitry. Our model proposes that key aspects of energy homeostasis brain circuitry already are functional by the time of birth (with substantial interindividual variation); that this phenotypic variation at birth is an important determinant of subsequent susceptibility for energy imbalance and childhood obesity risk; and that this brain circuitry exhibits developmental plasticity, in that it is influenced by conditions during intrauterine life, particularly maternal-placental-fetal endocrine, immune/inflammatory, and metabolic processes and their upstream determinants. We review evidence that supports the scientific premise for each element of this formulation, identify future research directions, particularly recent advances that may facilitate a better quantification of the ontogeny of energy homeostasis brain networks, highlight animal and in vitro-based approaches that may better address the determinants of interindividual variation in energy homeostasis brain networks, and discuss the implications of this formulation for the development of strategies targeted towards the primary prevention of childhood obesity.

Total energy expenditure is repeatable in adults but not associated with short-term changes in body composition

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested.

A narrative review on the application of doubly labeled water method for estimating energy requirement for Koreans

Research articles were reviewed to validate the estimated energy requirements (EERs) equations developed by the Institute of Medicine of the National Academies (IOM). These equations are based on total energy expenditure (TEE) measured by the doubly labeled water (DLW) method. We subsequently aimed to provide the basis for the suitability to apply the IOM equations as EER equations for Koreans, and develop relevant equations for EER in the Dietary Reference Intake for Koreans (KDRI). Additionally, besides the EER(IOM) equations, other equations were examined for EER estimation. Research papers demonstrating the validation of the EER(IOM) equations based on TEE(DLW) were searched through PubMed (up to September 2019). Of the 637 potentially relevant articles identified, duplicates and unsuitable titles and abstracts were excluded. Furthermore, papers with irrelevant subject and inappropriate study design were also excluded. Finally, 11 papers were included in the review. Among the reviewed papers, 8 papers validated the application of the EER(IOM) equations for EER based on TEE(DLW). These included 3 studies for children (USA 1, Korea 2), 1 for adolescents (Portugal), 2 for adults (Korean), and 2 for the elderly (Korea, USA). EER(IOM) equations were found to be generally acceptable for determining EER by using the DLW method, except for Korean boys at 9–11 yrs (overestimated) and female athletes at 19–24 yrs (underestimated). Additionally, 5 papers include the validation of other EER equations, beside EER(IOM) for EER based on TEE(DLW). In Japanese dietary reference intake and recommended dietary allowance, EER equations are acceptable for determining EER based on TEE(DLW). The EER(IOM) equations is generally acceptable for determining EER using the DLW method in Koreans as well as several populations, although certain defined groups were found to be unfit for the estimation. Additionally, the concept of healthy body mass index of Koreans and physical activity levels need to be considered, thereby providing the basis for developing relevant equations of EER in KDRI.

Calorie restriction improves lipid-related emerging cardiometabolic risk factors in healthy adults without obesity: Distinct influences of BMI and sex from CALERIE™ a multicentre, phase 2, randomised controlled trial

BACKGROUND

For many cardiovascular risk factors there is no lower limit to which further reduction will result in decreased disease risk; this includes values within ranges considered normal for healthy adults. This seems to be true for new emerging metabolic risk factors identified by innovative technological advances. Further, there seems to be ever evolving evidence of differential responses to lifestyle interventions by sex and body compositions in the normal range. In this secondary analysis, we had the opportunity to test these principles for newly identified molecular biomarkers of cardiometabolic risk in a young (21-50 years), normal weight healthy population undergoing calorie restriction for two years.

METHODS

The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE™) was a 24-month, multicenter, randomized controlled trial (May 2007-November 2012) in healthy, adults without obesity to evaluate the potential for calorie restriction (CR) to promote anti-aging adaptations, including those associated with disease risk. 218 participants (age 37.9 ± 7.2 years and body mass index (BMI) 25.1 ± 1.7 kg/m², mean±SD) were randomized 2:1 to 24 months of CR (prescribed as 25% reduction from baseline calorie intake) versus ad libitum (AL). Fasting plasma from baseline, 12, and 24 months was used for assessments of lipoproteins, metabolites, and inflammatory markers using nuclear magnetic resonance spectroscopy.

FINDINGS

Averaging 11.9% CR, the CR group had reductions at 12 and 24 months in the cardiovascular disease risk markers, apolipoprotein B and GlycA, and risks for insulin resistance and type 2 diabetes-Lipoprotein Insulin Resistance Index and Diabetes Risk Index (all P_CRvsAL ≤0.0009). Insulin resistance and diabetes risk improvements resulted from CR-induced alterations in lipoproteins, specifically reductions in triglyceride-rich lipoprotein particles and low-density lipoprotein particles, a shift to larger high-density lipoprotein particles (more effective cholesterol transporters), and reductions in branched chain amino acids (BCAAs) (all P_CRvsAL ≤0.004). These CR responses were more pronounced in overweight than normal weight participants and greater in men than women.

INTERPRETATION

In normal to slightly overweight adults without overt risk factors or disease, 12 months of ∼12% CR improved newly identified risk markers for atherosclerotic cardiovascular disease, insulin resistance and type 2 diabetes. These markers suggest that CR improves risks by reducing inflammation and BCAAs and shifting lipoproteins from atherogenic to cholesterol transporting. Additionally, these improvements are greater for men and for those with greater BMIs indicating sex and BMI-influences merit attention in future investigations of lifestyle-mediated improvements in disease risk factors.

FUNDING

The CALERIE™ trial design and implementation were supported by a National Institutes of Health (NIH) U-grant provided to four institutions, the three intervention sites and a coordinating center (U01 AG022132, U01 AG020478, U01 AG020487 U01 AG020480). For this secondary analysis including sample acquisition and processing, data analysis and interpretation, additional funding was provided by the NIH to authors as follows: R01 AG054840 (MO, VBK); R33 AG070455 (KMH, DCP, MB, SBR, CKM, LMR, SKD, CFP, CJR, WEK); P30 DK072476 (CKM, LMR); and U54 GM104940 (CKM, LMR).

Accuracy and Practical Considerations for Doubly Labeled Water Analysis in Nutrition Studies Using a Laser-Based Isotope Instrument (Off-Axis Integrated Cavity Output Spectroscopy)

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.

Effect of 2-year caloric restriction on organ and tissue size in nonobese 21- to 50-year-old adults in a randomized clinical trial: the CALERIE study

BACKGROUND

Sustained calorie restriction (CR) promises to extend the lifespan. The effect of CR on changes in body mass across tissues and organs is unclear.

OBJECTIVES

We used whole-body MRI to evaluate the effect of 2 y of CR on changes in body composition.

METHODS

In an ancillary study of the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trial, 43 healthy adults [25-50 y; BMI (kg/m2): 22-28] randomly assigned to 25% CR (n = 28) or ad libitum (AL) eating (n = 15) underwent whole-body MRI at baseline and month 24 to measure adipose tissue in subcutaneous, visceral, and intermuscular depots (SAT, VAT, and IMAT, respectively); skeletal muscle; and organs including brain, liver, spleen, and kidneys but not heart.

RESULTS

The CR group lost more adipose tissue and lean tissue than controls (P < 0.05). In the CR group, at baseline, total tissue volume comprised 32.1%, 1.9%, and 1.0% of SAT, VAT, and IMAT, respectively. The loss of total tissue volume over 24 mo comprised 68.4%, 7.4%, and 2.2% of SAT, VAT, and IMAT, respectively, demonstrating preferential loss of fat vs. lean tissue. Although there is more muscle loss in CR than AL (P < 0.05), the loss of muscle over 24 mo in the CR group comprised only 17.2% of the loss of total tissue volume. Changes in organ volumes were not different between CR and AL. The degree of CR (% decrease in energy intake vs. baseline) significantly (P < 0.05) affected changes in VAT, IMAT, muscle, and liver volume (standardized regression coefficient ± standard error of estimates: 0.43 ± 0.15 L, 0.40 ± 0.19 L, 0.55 ± 0.17 L, and 0.45 ± 0.18 L, respectively).

CONCLUSIONS

Twenty-four months of CR (intended, 25%; actual, 13.7%) in young individuals without obesity had effects on body composition, including a preferential loss of adipose tissue, especially VAT, over the loss of muscle and organ tissue. This trial was registered at www.clinicaltrials.gov as NCT02695511.

Structured supervised exercise training or motivational counselling during pregnancy on physical activity level and health of mother and offspring: FitMum study protocol

INTRODUCTION

A physically active lifestyle during pregnancy improves maternal and offspring health but can be difficult to follow. In Denmark, less than 40% of pregnant women meet physical activity (PA) recommendations. The FitMum study aims to explore strategies to increase PA during pregnancy among women with low PA and assess the health effects of PA. This paper presents the FitMum protocol, which evaluates the effects of structured supervised exercise training or motivational counselling supported by health technology during pregnancy on PA level and health of mother and offspring.

METHODS AND ANALYSIS

A single-site three-arm randomised controlled trial that aims to recruit 220 healthy, pregnant women with gestational age (GA) no later than week 15 and whose PA level does not exceed one hour/week. Participants are randomised to one of three groups: structured supervised exercise training consisting of three weekly exercise sessions, motivational counselling supported by health technology or a control group receiving standard care. The interventions take place from randomisation until delivery. The primary outcome is min/week of moderate-to-vigorous intensity PA (MVPA) as determined by a commercial activity tracker, collected from randomisation until GA of 28 weeks and 0-6 days, and the secondary outcome is gestational weight gain (GWG). Additional outcomes are complementary measures of PA; clinical and psychological health parameters in participant, partner and offspring; analyses of blood, placenta and breastmilk samples; process evaluation of interventions; and personal understandings of PA.

ETHICS AND DISSEMINATION

The study is approved by the Danish National Committee on Health Research Ethics (# H-18011067) and the Danish Data Protection Agency (# P-2019-512). Findings will be disseminated via peer-reviewed publications, at conferences, and to health professionals via science theatre performances.

TRIAL REGISTRATION NUMBER

NCT03679130.

PROTOCOL VERSION

This paper was written per the study protocol version 8 dated 28 August 2019.

Effects of caloric restriction on human physiological, psychological, and behavioral outcomes: highlights from CALERIE phase 2

Caloric restriction (CR) is a strategy that attenuates aging in multiple nonhuman species. The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trials are part of a research program aiming to test the effects of CR on aging and longevity biomarkers in humans. Building on CALERIE phase 1, CALERIE phase 2 (CALERIE 2) was the largest study to date to assess sustained CR in healthy humans without obesity. In a 24-month randomized controlled trial comprising 218 participants at baseline, CALERIE 2 showed that moderate CR, 11.9% on average, induced improvements in aging-related biomarkers without adversely affecting psychological or behavioral outcomes. The objectives of this report are to summarize and review the highlights of CALERIE 2 and report previously unpublished results on eating disorder symptoms and cognitive function. This article specifically summarizes the physiological, psychological, aging, behavioral, and safety results of the trial. Also provided are research directions beyond CALERIE 2 that highlight important opportunities to investigate the role of CR in aging, longevity, and health span in humans.

Calorie restriction for enhanced longevity: The role of novel dietary strategies in the present obesogenic environment

Calorie restriction (CR) is a potent modulator of longevity in multiple species. A growing body of evidence shows that sustained periods of CR without malnutrition improves risk factors involved in the pathophysiology of type 2 diabetes, cardiovascular diseases, cancer, and neurological disorders in humans. Innovative dietary strategies such as intermittent fasting and protein restriction have recently emerged as alternative approaches that improve markers of aging. Some of these newer strategies might provide benefits for healthy aging with little to no CR and therefore, compared to traditional CR, may be easier to follow. Further to providing an update of CR studies in humans, the present narrative review appraises the influence of these contemporary dietary strategies on mechanisms posited to drive CR-induced longevity in humans, including those involving energy metabolism, oxidative damage, inflammation, glucose homeostasis, and functional changes in the neuroendocrine systems. The review also discusses the utilization of these diets for populations in the current obesogenic environment, and comments on whether current research can inform an optimal diet that attenuates aging, can be easily followed, and promises to improve longevity in humans.

Validation of saliva and urine use and sampling time on the doubly labelled water method to measure energy expenditure, body composition and water turnover in male and female cats

Less invasive protocols are necessary to study energy expenditure (EE) of cats living in homes for expressing their normal living conditions. The present study compared sampling times and the use of saliva, urine and blood to measure 2H and 18O to apply the doubly labelled water method. In the first study, four cats were used to evaluate the enrichment (2, 4, 6, 7 and 8 h) and elimination (2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 d) of 2H and 18O (subcutaneously injected). The maximum enrichment was after 5 h (R2 0·82) of injection, with an Ln linear elimination of both isotopes (P < 0·001; R2 0·99). The results of EE were similar, regardless of the sampling time used (P = 0·999). In the second study, seven male cats and seven female cats were used. Before and after isotope injection (5 h, 7 d, 10 d and 14 d), blood, saliva and urine were collected. Isotope enrichment was lower in urine (P < 0·05) and at the similar level in blood and saliva. Isotope elimination was similar for all fluids (P < 0·473). The EE calculated with blood and saliva was similar but higher for urine (P = 0·015). According to Bland-Altman statistics, blood and saliva presented low bias and high correlation (P < 0·001), but this was not observed for urine (P = 0·096). Higher EE was observed for male cats (384 (se 39) kJ/kg0·67 per d) than for female cats (337 (se 34) kJ/kg0·67 per d; P < 0·05). The sampling time for the method is flexible, and saliva can be used as a substitute for blood.

Quantification of the pace of biological aging in humans through a blood test, the DunedinPoAm DNA methylation algorithm

Biological aging is the gradual, progressive decline in system integrity that occurs with advancing chronological age, causing morbidity and disability. Measurements of the pace of aging are needed as surrogate endpoints in trials of therapies designed to prevent disease by slowing biological aging. We report a blood-DNA-methylation measure that is sensitive to variation in pace of biological aging among individuals born the same year. We first modeled change-over-time in 18 biomarkers tracking organ-system integrity across 12 years of follow-up in n = 954 members of the Dunedin Study born in 1972-1973. Rates of change in each biomarker over ages 26-38 years were composited to form a measure of aging-related decline, termed Pace-of-Aging. Elastic-net regression was used to develop a DNA-methylation predictor of Pace-of-Aging, called DunedinPoAm for Dunedin(P)ace(o)f(A)ging(m)ethylation. Validation analysis in cohort studies and the CALERIE trial provide proof-of-principle for DunedinPoAm as a single-time-point measure of a person's pace of biological aging.

Nonalcoholic Beverages as Sources of Nutrients in the Average Polish Diet

The aim of the study was to analyze the sources of energy, carbohydrates, 10 minerals, and 9 vitamins from nonalcoholic beverages in the average Polish diet. For the analysis, we used data from the 2016 Household Budget Survey conducted on the representative sample of the Polish population (36,886 households, n = 99,230). According to the source of data, we included four subgroups in analyzed food category: fruit juices, vegetable juices and mixed, mineral and spring waters, and other nonalcoholic beverages. We used the cluster analysis to assess the impact of sociodemographic and economic characteristics of the households on the structure of supplying energy and nutrients from each subgroup of the nonalcoholic beverages. Our analyses have shown that nonalcoholic beverages are primarily important in providing several nutrients: vitamin C (15.9% of the total vitamin C supply), vitamin B6 (8.9% of vitamin B supply), folates (8.5% of folate supply), carbohydrates (6.8% of carbohydrate supply), calcium (5.9% of calcium supply), and magnesium (5.5% of magnesium supply). The analysis of the consumption structure of this category of food showed that the subgroup of other nonalcoholic beverages brings more than three-fourth of carbohydrates (77%), vitamin B6 and folates (76% each), and 43% of vitamin C supplied by nonalcoholic beverages. More than half (51%) of vitamin C provided by nonalcoholic beverages comes from fruit juices and the remaining 6% comes from other juices (vegetable and mixed). In the case of minerals, mineral and spring waters consumption is important as it accounts for 65% of the calcium supply and 55% of the magnesium in nonalcoholic beverages category. The share of individual subgroups of beverages in the supply of ingredients in the diet is significantly differentiated by four socioeconomic characteristics of households: family life phase, age, socioeconomic type of household, and number of people in the household. This is particularly evident in the case of other nonalcoholic beverages, that the share of this subgroup in the energy and carbohydrates supply in the households of young people, employees (both blue-collar and white-collar workers), and families with children increases to 10%. Our results show that in order to reduce the intake of free sugars and increase the intake of deficient minerals, which is crucial in preventing noncommunicable diseases (NCDs), it is necessary to encourage consumers to replace sugar-sweetened beverages (SSBs) with water and eat fruits instead of drinking juice.

How Important are Cereals and Cereal Products in the Average Polish Diet?

The main aim of this study was to identify the food sources of energy and 28 nutrients from cereals and cereal products in the average Polish diet based on data from a nationally representative sample of the Polish population attending in 2016 Household Budget Survey (i.e., 36,886 households). The contribution of energy and nutrients from cereals and cereal products were compared with reference values. The detailded analysis included five main groups and nine sub-groups of cereal food category. Our findings indicated that cereals and cereal products contributed 30.4% of total dietary energy supply, providing a significant percentage of six nutrients to the average Polish diet (i.e., 64.1% of manganese, 51% of carbohydrates, 48.5% of dietary fibre, 34.1% of iron, 33.6% of folate, and 31.3% of copper). Supply at the level of 20⁻30% was observed for protein, thiamin, phosphorus and zinc, and at 10⁻20% for polyunsaturated fatty acids (PUFA), sodium, potassium, calcium, riboflavin, niacin, and vitamin B6. For other nutrients i.e., total fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), cholesterol, iodine, vitamins: A, D, B12, and C, the share of cereals and cereal products contribution was below 10%. Cereals and cereal products were the major food category in meeting the reference values for the Polish population in case of manganese, carbohydrates (approximately100%), and sodium (50%). The reference values was reached at the level of 30⁻40% for dietary fibre, protein, iron, copper, zinc, phosphorus and thiamin, and 20⁻30% for energy, magnesium, folate, niacin, riboflavin, vitamins B6 and E. For such nutrients as total fat, SFA, and potassium, the fulfillment of the reference values amounted to 10⁻20%. Our results document the importance of cereals and cereal products in the Polish diet, which should be emphasized from a nutritional and health point of view.

Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial

OBJECTIVE

To determine the effects of diets varying in carbohydrate to fat ratio on total energy expenditure.

DESIGN

Randomized trial.

SETTING

Multicenter collaboration at US two sites, August 2014 to May 2017.

PARTICIPANTS

164 adults aged 18-65 years with a body mass index of 25 or more.

INTERVENTIONS

After 12% (within 2%) weight loss on a run-in diet, participants were randomly assigned to one of three test diets according to carbohydrate content (high, 60%, n=54; moderate, 40%, n=53; or low, 20%, n=57) for 20 weeks. Test diets were controlled for protein and were energy adjusted to maintain weight loss within 2 kg. To test for effect modification predicted by the carbohydrate-insulin model, the sample was divided into thirds of pre-weight loss insulin secretion (insulin concentration 30 minutes after oral glucose).

MAIN OUTCOME MEASURES

The primary outcome was total energy expenditure, measured with doubly labeled water, by intention-to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate. Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.

RESULTS

Total energy expenditure differed by diet in the intention-to-treat analysis (n=162, P=0.002), with a linear trend of 52 kcal/d (95% confidence interval 23 to 82) for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ). Change in total energy expenditure was 91 kcal/d (95% confidence interval -29 to 210) greater in participants assigned to the moderate carbohydrate diet and 209 kcal/d (91 to 326) greater in those assigned to the low carbohydrate diet compared with the high carbohydrate diet. In the per protocol analysis (n=120, P<0.001), the respective differences were 131 kcal/d (-6 to 267) and 278 kcal/d (144 to 411). Among participants in the highest third of pre-weight loss insulin secretion, the difference between the low and high carbohydrate diet was 308 kcal/d in the intention-to-treat analysis and 478 kcal/d in the per protocol analysis (P<0.004). Ghrelin was significantly lower in participants assigned to the low carbohydrate diet compared with those assigned to the high carbohydrate diet (both analyses). Leptin was also significantly lower in participants assigned to the low carbohydrate diet (per protocol).

CONCLUSIONS

Consistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance. This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02068885.

Adherence of Malaysian Adults' Energy and Macronutrient Intakes to National Recommendations: A Review and Meta-Analysis

The present study examined the best available evidence regarding energy and macronutrient intake during adulthood (age 19 to 59 years) in Malaysia and assessed whether intakes adhere to national recommendations, in order to develop recommendations for dietary improvement based on population consumption patterns. A literature review and meta-analysis evaluated intake based on the following characteristics, using information from food balance sheets, national surveys, and individual studies: (1) levels of intake, (2) proportion of the population whose diets adhere to/exceed/fail to meet Malaysian Recommended Nutrient Intake (RNI) levels, and (3) sources of macronutrients observed in these studies. Food balance data suggested high levels of available energy, animal source protein, vegetable fat, and refined carbohydrates. Twenty studies (five nationwide, 15 individual) indicated that Malaysian adults generally met or exceeded recommendations for fat and protein, but were inconsistent with respect to energy and carbohydrates. Information on dietary sources was limited. Due to methodological limitations, insufficient evidence exists regarding energy and macronutrient intakes of Malaysian adults. Improved dietary assessment methods (including use of biomarkers), better data analysis, and updated food composition data, will provide more reliable information on which to base policy decisions and recommendations for improvement.

Validation of Dietary Reference Intakes for predicting energy requirements in elementary school-age children

BACKGROUND/OBJECTIVES

Dietary Reference Intakes (DRI) for energy are derived from total energy expenditure (TEE) measured using the doubly labelled water (DLW) method. The objective of this study was to assess the validity of DRI for predicting the energy requirements of elementary school-age children.

SUBJECTS/METHODS

The present study involved 25 elementary school-age children aged between 9 and 11 years. TEE was assessed by the DLW method, and the results were compared with the TEE predicted by the DRI equations in order to evaluate accuracy.

RESULTS

The subjects' TEE measured by the DLW method was 1,925.2 ± 380.9 kcal/day in boys and 1,930.0 ± 279.4 kcal/day in girls, whereas resting energy expenditure was 1,220.2 ± 176.9 kcal/day in boys and 1,245.9 ± 171.3 kcal/day for girls. The physical activity level was 1.58 ± 0.20 in boys and 1.55 ± 0.13 in girls. The mean bias between the predicted and measured TEE was 12.6% in boys and −1.6% in girls, and the percentage of accurate predictions was 28.6% and 63.6%, respectively. In boys, the equation resulted in underprediction of TEE among the subjects having low TEE values, whereas there was overprediction among subjects having high TEE values as shown by the Bland-Altman plot. On the contrary, this proportional bias was not observed in girls.

CONCLUSIONS

The findings of this study suggest that the DRI equation for energy could result in the overestimation of energy requirements in elementary school-age boys. In the case of girls, the equations could be accurate at the group level. However, the DRI appears to be invalid for individual girls, as more than one third of girls had their TEE inaccurately predicted. We recommend more studies for confirmation of these results.

Metabolic Aspects of Aging

Metabolic interventions involving undernutrition but not malnutrition (e.g., caloric restriction, CR) are effective strategies for improving both health and longevity in species ranging from lower organisms to nonhuman primates. Initial human trials to test the effects of sustained, reduced energy intake have yielded promising health benefits. Through intense research efforts in understanding the molecular mechanisms of CR, three cellular pathways have now been identified although the precise details remain unknown. More recently, circadian regulation has been recognized as a novel mediator for CR effects in mice. Harnessing the molecular insights into CR, novel nutritional interventions and pharmacological application of CR mimetics have been tested showing great promise in simultaneously improving metabolic function and providing overall health benefits. Additional research is needed to identify efficacious therapeutics that can be safely and practically translated to human studies in promoting healthspan.

A randomized study of dietary composition during weight-loss maintenance: Rationale, study design, intervention, and assessment

BACKGROUND

While many people with overweight or obesity can lose weight temporarily, most have difficulty maintaining weight loss over the long term. Studies of dietary composition typically focus on weight loss, rather than weight-loss maintenance, and rely on nutrition education and dietary counseling, rather than controlled feeding protocols. Variation in initial weight loss and insufficient differentiation among treatments confound interpretation of results and compromise conclusions regarding the weight-independent effects of dietary composition. The aim of the present study was to evaluate three test diets differing in carbohydrate-to-fat ratio during weight-loss maintenance.

DESIGN AND DIETARY INTERVENTIONS

Following weight loss corresponding to 12±2% of baseline body weight on a standard run-in diet, 164 participants aged 18 to 65years were randomly assigned to one of three test diets for weight-loss maintenance through 20weeks (test phase). We fed them high-carbohydrate (60% of energy from carbohydrate, 20% fat), moderate-carbohydrate (40% carbohydrate, 40% fat), and low-carbohydrate (20% carbohydrate, 60% fat) diets, controlled for protein content (20% of energy). During a 2-week ad libitum feeding phase following the test phase, we assessed the effect of the test diets on body weight.

OUTCOMES

The primary outcome was total energy expenditure, assessed by doubly-labeled water methodology. Secondary outcomes included resting energy expenditure and physical activity, chronic disease risk factors, and variables to inform an understanding of physiological mechanisms by which dietary carbohydrate-to-fat ratio might influence metabolism. Weight change during the ad libitum feeding phase was conceptualized as a proxy measure of hunger.

Change in the Rate of Biological Aging in Response to Caloric Restriction: CALERIE Biobank Analysis

Biological aging measures have been proposed as proxies for extension of healthy life span in trials of geroprotective therapies that aim to slow aging. Several methods to measure biological aging show promise but it is not known if these methods are sensitive to changes caused by geroprotective therapy. We conducted analysis of two proposed methods to quantify biological aging using data from a recently concluded trial of an established geroprotector, caloric restriction. We obtained data from the National Institute on Aging CALERIE randomized trial through its public-access biobank (https://calerie.duke.edu/). The CALERIE trial randomized N = 220 nonobese adults to 25% caloric restriction (n = 145; 11.7% caloric restriction was achieved, on average) or to maintain current diet (n = 75) for 2 years. We analyzed biomarker data collected at baseline, 12-, and 24-month follow-up assessments. We applied published biomarker algorithms to these data to calculate two biological age measures, Klemera-Doubal Method Biological Age and homeostatic dysregulation. Intent-to-treat analysis using mixed-effects growth models of within-person change over time tested if caloric restriction slowed increase in measures of biological aging across follow-up. Analyses of both measures indicated caloric restriction slowed biological aging. Weight loss did not account for the observed effects. Results suggest future directions for testing of geroprotective therapies in humans.

Validation of dietary reference intake equations for estimating energy requirements in Korean adults by using the doubly labeled water method

BACKGROUND/OBJECTIVES

The doubly labeled water (DLW) method is considered the gold standard for the measurement of total energy expenditure (TEE), which serves to estimate energy requirements. This study evaluated the accuracy of predictive dietary reference intake (DRI) equations for determining the estimated energy requirements (EER) of Korean adults by using the DLW as a reference method.

SUBJECTS/METHODS

Seventy-one participants (35 men and 36 women) aged between 20 and 49 years were included in the study. The subjects' EER, calculated by using the DRI equation (EER_DRI), was compared with their TEE measured by the DLW method (TEE_DLW).

RESULTS

The DRI equations for EER underestimated TEE by -36.3 kcal/day (-1.3%) in men and -104.5 kcal/day (-4.9%) in women. The percentages of accurate predictions among subjects were 77.1% in men and 62.9% in women. There was a strong linear correlation between EER_DRI and TEE_DLW (r=0.783, P<0.001 in men and r=0.810, P<0.001 in women).

CONCLUSIONS

The present study supports the use of DRI prediction equations to determine EER in Korean adults. More studies are needed to confirm our results and to assess the validity of these equations in other population groups, including children, adolescents, and older adults.

Energy Intake and Energy Expenditure for Determining Excess Weight Gain in Pregnant Women

OBJECTIVE

To conduct a secondary analysis designed to test whether gestational weight gain is the result of increased energy intake or adaptive changes in energy expenditures.

METHODS

In this secondary analysis, energy intake and energy expenditure of 45 pregnant women (body mass index [BMI] 18.5-24.9 [n=33] and BMI 25 or greater [n=12]) were measured preconceptionally and at 22 and 36 weeks of gestation. Energy intake was calculated as the sum of total energy expenditure measured by doubly-labeled water and energy deposition determined by the four-compartment body composition model. Measurements of weight, body composition, and basal metabolic rate were completed preconceptionally and 9, 22, and 36 weeks of gestation. Basal metabolic rate was measured by indirect calorimetry in a room calorimeter and activity energy expenditure by doubly-labeled water.

RESULTS

Energy intake from 22 to 36 weeks of gestation was significantly higher in high gainers (n=19) (3,437±99 kcal per day) compared with low+ideal gainers (n=26) (2,687±110, P<.001) within both BMI categories. Basal metabolic rate increased in proportion to gestational weight gain; however, basal metabolic rate adjusted for body composition changes with gestational weight gain was not significantly different between high gainers and low+ideal gainers (151±33 compared with 129±36 kcal per day; P=.66). Activity energy expenditure decreased throughout pregnancy in both groups (low+ideal gainers: -150±70 kcal per day; P=.04 and high gainers: -230±92 kcal per day; P=.01), but there was no difference between high gainers and low+ideal gainers (P=.49).

CONCLUSION

Interventions designed to increase adherence to the Institute of Medicine guidelines for weight gain in pregnancy may have increased efficacy if focused on limiting energy intake while increasing nutrient density and maintaining levels of physical activity.

Measurement Methods for Physical Activity and Energy Expenditure: a Review

Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure. The benefits of physical activity for health maintenance have been well documented, especially in the prevention and management of chronic diseases. Therefore, accurate measurement of physical activity and energy expenditure is essential both for epidemiological studies and in the clinical context. Given the large number of available methods, it is important to have an understanding of each, especially when one needs to choose a technique to use. The purpose of this review was to discuss the components of total energy expenditure and present advantage and limitations of different methods of physical activity and energy expenditure assessment.

Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-y randomized controlled trial of calorie restriction in nonobese humans

Background: Calorie restriction (CR) retards aging and increases longevity in many animal models. However, it is unclear whether CR can be implemented in humans without adverse effects on body composition.Objective: We evaluated the effect of a 2-y CR regimen on body composition including the influence of sex and body mass index (BMI; in kg/m²) among participants enrolled in CALERIE-2 (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy), a multicenter, randomized controlled trial.Design: Participants were 218 nonobese (BMI: 21.9-28.0) adults aged 21-51 y who were randomly assigned to 25% CR (CR, n = 143) or ad libitum control (AL, n = 75) in a 2:1 ratio. Measures at baseline and 12 and 24 mo included body weight, waist circumference, fat mass (FM), fat-free mass (FFM), and appendicular mass by dual-energy X-ray absorptiometry; activity-related energy expenditure (AREE) by doubly labeled water; and dietary protein intake by self-report. Values are expressed as means ± SDs.Results: The CR group achieved 11.9% ± 0.7% CR over 2-y and had significant decreases in weight (-7.6 ± 0.3 compared with 0.4 ± 0.5 kg), waist circumference (-6.2 ± 0.4 compared with 0.9 ± 0.5 cm), FM (-5.4 ± 0.3 compared with 0.5 ± 0.4 kg), and FFM (-2.0 ± 0.2 compared with -0.0 ± 0.2 kg) at 24 mo relative to the AL group (all between-group P < 0.001). Moreover, FFM as a percentage of body weight at 24 mo was higher, and percentage of FM was lower in the CR group than in the AL. AREE, but not protein intake, predicted preservation of FFM during CR (P < 0.01). Men in the CR group lost significantly more trunk fat (P = 0.03) and FFM expressed as a percentage of weight loss (P < 0.001) than women in the CR group.Conclusions: Two years of CR had broadly favorable effects on both whole-body and regional adiposity that could facilitate health span in humans. The decrements in FFM were commensurate with the reduced body mass; although men in the CR group lost more FFM than the women did, the percentage of FFM in the men in the CR group was higher than at baseline. CALERIE was registered at clinicaltrials.gov as NCT00427193.

Total Energy Expenditure in Obese Kuwaiti Primary School Children Assessed by the Doubly-Labeled Water Technique

The aim of this pilot study was to assess body composition and total energy expenditure (TEE) in 35 obese 7–9 years old Kuwaiti children (18 girls and 17 boys). Total body water (TBW) and TEE were assessed by doubly-labeled water technique. TBW was derived from the intercept of the elimination rate of deuterium and TEE from the difference in elimination rates of ¹⁸O and deuterium. TBW was used to estimate fat-free mass (FFM), using hydration factors for different ages and gender. Fat mass (FM) was calculated as the difference between body weight and FFM. Body weight was not statistically different but TBW was significantly higher (p = 0.018) in boys (44.9% ± 3.3%) than girls (42.4% ± 3.0%), while girls had significantly higher estimated FM (45.2 ± 3.9 weight % versus 41.6% ± 4.3%; p = 0.014). TEE was significantly higher in boys (2395 ± 349 kcal/day) compared with girls (1978 ± 169 kcal/day); p = 0.001. Estimated physical activity level (PAL) was significantly higher in boys; 1.61 ± 0.167 versus 1.51 ± 0.870; p = 0.034. Our results provide the first dataset of TEE in 7–9 years old obese Kuwaiti children and highlight important gender differences to be considered during the development of school based interventions targeted to combat childhood obesity.

A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity

BACKGROUND

Caloric restriction (CR), energy intake reduced below ad libitum (AL) intake, increases life span in many species. The implications for humans can be clarified by randomized controlled trials of CR.

METHODS

To determine CR's feasibility, safety, and effects on predictors of longevity, disease risk factors, and quality of life in nonobese humans aged 21-51 years, 218 persons were randomized to a 2-year intervention designed to achieve 25% CR or to AL diet. Outcomes were change from baseline resting metabolic rate adjusted for weight change ("RMR residual") and core temperature (primary); plasma triiodothyronine (T3) and tumor necrosis factor-α (secondary); and exploratory physiological and psychological measures.

RESULTS

Body mass index averaged 25.1 (range: 21.9-28.0 kg/m(2)). Eighty-two percent of CR and 95% of AL participants completed the protocol. The CR group achieved 11.7±0.7 %CR (mean ± standard error) and maintained 10.4±0.4% weight loss. Weight change in AL was negligible. RMR residual decreased significantly more in CR than AL at 12 months (p = .04) but not 24 months (M24). Core temperature change differed little between groups. T3 decreased more in CR at M12 and M24 (p < .001), while tumor necrosis factor-α decreased significantly more only at M24 (p = .02). CR had larger decreases in cardiometabolic risk factors and in daily energy expenditure adjusted for weight change, without adverse effects on quality of life.

CONCLUSIONS

Sustained CR is feasible in nonobese humans. The effects of the achieved CR on correlates of human survival and disease risk factors suggest potential benefits for aging-related outcomes that could be elucidated by further human studies.

Weight gain and reduced energy expenditure in low-income Brazilian women living in slums: a 4-year follow-up study

The present study aimed to investigate the possible changes in anthropometric and biochemical parameters in low-income women living in the outskirts of Maceió (northeast Brazil), and to explore the possible role of dietary intake and physical activity in these changes. A prospective longitudinal study was conducted in a cohort of mothers of malnourished children who attended the Center for Nutritional Recovery and Education, an outreach programme of the Federal University of Alagoas. Socio-economic, anthropometric, biochemical and dietary intake data were assessed at baseline and after a follow-up period of 4 years. Energy expenditure (using doubly labelled water) and physical activity (using triaxial accelerometers) were assessed only in a subgroup of women after 4 years. A total of eighty-five women were assessed. Participants showed an altered biochemical profile, increased systolic blood pressure, decreased thyroid hormone levels, and body-weight gain. However, dietary intakes of the participants did not include large quantities of highly processed and high-glycaemic index foods. The energy intake of the participants did not differ from their total energy expenditure (7990·3 (7173·7–8806·8)v. 8798·1 (8169·0–9432·4) kJ, respectively;P= 0·084). Multivariate analyses showed a significant effect of time spent watching television (β = 0·639 (0·003 to 1·275);P= 0·048) and dietary diversity score (β = − 1·039 ( − 2·010 to − 0·067);P= 0·036) on weight gain. The present study indicates that poor women, who are mothers of malnourished children and have a reasonably balanced dietary intake, exhibit weight gain and are at risk of developing chronic diseases.

Portion-controlled meals provide increases in diet quality during weight loss and maintenance

BACKGROUND

Behavioural weight-loss interventions utilising portion-controlled meals (PCMs) produce significant decreases in weight. However, their impact on diet quality during weight maintenance is unknown. The present study aimed to assess the influence of a weight management intervention employing PCMs and increased physical activity on diet quality during weight loss and weight maintenance.

METHODS

One hundred and ninety-seven overweight and obese adults [67% women; mean (SD) BMI = 34.0 (4.6) kg m(-2); age = 46.1 (8.9) years] completed an 18-month trial. The weight-loss phase (0-6 months) consisted of energy restriction, which was achieved using PCMs plus fruits and vegetables and increased physical activity. During weight maintenance (6-18 months), participants consumed a diet designed to maintain weight loss. Body weight and dietary intake were assessed at baseline, and at 6, 12 and 18 months. The Healthy Eating Index-2010 (HEI) was calculated using data obtained from 3-day food records.

RESULTS

Mean (SD) body weight was 14.3% (6.6%) and 8.7% (8.0%) below baseline at 6 and 18 months, respectively. The mean (SD) HEI-2010 score after weight loss [66.6 (9.4)] was significantly higher than baseline [46.4 (8.9)] and remained significantly higher than baseline at 18 months [57.7 (10.6)] (both P < 0.001).

CONCLUSIONS

A weight management intervention using PCMs resulted in both clinically significant weight loss and increased diet quality scores, demonstrating that the use of PCMs during weight loss allows for meaningful changes in diet quality during weight maintenance.

Meal timing during alternate day fasting: Impact on body weight and cardiovascular disease risk in obese adults

OBJECTIVE

Alternate day fasting (ADF; 24-h feeding/24-h 25% energy intake at lunchtime), is effective for weight loss, but diet tolerability is questionable. Moving the fast day meal to dinnertime, or dividing it into smaller meals, may improve tolerability. Accordingly, this study compared the effects of ADF with three meal times on body weight and heart disease risk.

METHODS

Obese subjects (n = 74) were randomized to 1 of 3 groups for 8 weeks: 1) ADF-L: lunch, 2) ADF-D: dinner, or 3) ADF-SM: small meals.

RESULTS

Body weight decreased similarly (P < 0.001) in all groups (ADF-L: 3.5 ± 0.4 kg, ADF-D 4.1 ± 0.5 kg, ADF-SM 4.0 ± 0.5 kg). Reductions (P < 0.001) in fat mass and visceral fat were also comparable. Plasma lipids remained unchanged, and low density lipoprotein (LDL) particle size increased (P < 0.05) in all groups (1.3 ± 0.5 Å). Systolic blood pressure decreased (P < 0.05) by ADF-SM only. Fasting glucose, insulin, and HOMA-IR remained unchanged.

CONCLUSIONS

Thus, allowing individuals to consume the fast day meal at dinner or small meals produces similar weight loss and cardio-protection as consuming the meal at lunch. This flexibility in meal timing may increase tolerability and long-term adherence to ADF protocols.

Assessment of physical activity and energy expenditure: an overview of objective measures

The ability to assess energy expenditure (EE) and estimate physical activity (PA) in free-living individuals is extremely important in the global context of non-communicable diseases including malnutrition, overnutrition (obesity), and diabetes. It is also important to appreciate that PA and EE are different constructs with PA defined as any bodily movement that results in EE and accordingly, energy is expended as a result of PA. However, total energy expenditure, best assessed using the criterion doubly labeled water (DLW) technique, includes components in addition to physical activity energy expenditure, namely resting energy expenditure and the thermic effect of food. Given the large number of assessment techniques currently used to estimate PA in humans, it is imperative to understand the relative merits of each. The goal of this review is to provide information on the utility and limitations of a range of objective measures of PA and their relationship with EE. The measures discussed include those based on EE or oxygen uptake including DLW, activity energy expenditure, physical activity level, and metabolic equivalent; those based on heart rate monitoring and motion sensors; and because of their widespread use, selected subjective measures.