Improving National and International Surveillance of Movement Behaviours in Childhood and Adolescence: An International Modified Delphi Study.

BACKGROUND: The actions required to achieve higher-quality and harmonised global surveillance of child and adolescent movement behaviours (physical activity, sedentary behaviour including screen time, sleep) are unclear. OBJECTIVE: To identify how to improve surveillance of movement behaviours, from the perspective of experts. METHODS: This Delphi Study involved 62 experts from the SUNRISE International Study of Movement Behaviours in the Early Years and Active Healthy Kids Global Alliance (AHKGA). Two survey rounds were used, with items categorised under: (1) funding, (2) capacity building, (3) methods, and (4) other issues (e.g., policymaker awareness of relevant WHO Guidelines and Strategies). Expert participants ranked 40 items on a five-point Likert scale from 'extremely' to 'not at all' important. Consensus was defined as > 70% rating of 'extremely' or 'very' important. RESULTS: We received 62 responses to round 1 of the survey and 59 to round 2. There was consensus for most items. The two highest rated round 2 items in each category were the following; for funding (1) it was greater funding for surveillance and public funding of surveillance; for capacity building (2) it was increased human capacity for surveillance (e.g. knowledge, skills) and regional or global partnerships to support national surveillance; for methods (3) it was standard protocols for surveillance measures and improved measurement method for screen time; and for other issues (4) it was greater awareness of physical activity guidelines and strategies from WHO and greater awareness of the importance of surveillance for NCD prevention. We generally found no significant differences in priorities between low-middle-income (n = 29) and high-income countries (n = 30) or between SUNRISE (n = 20), AHKGA (n = 26) or both (n = 13) initiatives. There was a lack of agreement on using private funding for surveillance or surveillance research. CONCLUSIONS: This study provides a prioritised and international consensus list of actions required to improve surveillance of movement behaviours in children and adolescents globally.

Isotope Dilution Space Ratio Declines Above the Age of 60 Years, Potentially Impacting Estimates of Total Energy Expenditure by the Doubly Labeled Water Method1-3, *, ˆ.

Doubly labeled water is gold standard for measuring total energy expenditure (TEE). Measurements using the method are sensitive to the isotope dilution space ratio (DSR). Accuracy and precision of the method might be improved if we could identify factors influencing DSR. We evaluated the potential associations of age, sex, ethnicity, anthropometry, body composition, turnover rates of the isotopes, and geographical elevation with DSR. We used univariate regression analysis to explore the relationships between the continuous variables and analysis of variance to test the relationships between the categorical variables with DSR. Subsequently, we used General Linear Modeling (GLM) and One-way ANOVA to evaluate the simultaneous associations of age, sex, ethnicity, fat-free mass (FFM) and fat mass (FM) on DSR. From 5,678 measurements complied from studies around the world with diverse ethnicity and living at various elevations, the average DSR was 1.0364 ± 0.0141 (mean ± SD). No meaningful physiological effect of any of the continuous and categorical variable on DSR was detected. GLM analysis revealed no effect of FFM and FM (P > 0.33) on DSR, but DSR decreased with age (P < 0.001) among those 60 years of age and older regardless of sex. Among the White who were younger than 60 years of age, DSR was not related to FFM and FM (P = 0.73) but was affected by both age and sex (P < 0.001). Previous estimates of age-related decline in TEE may have overestimated TEE at age 90. Validation studies on older participants are required to confirm this finding.

Pooled Analysis of Physical Activity, Sedentary Behavior, and Sleep Among Children From 33 Countries.

Importance: The prevalence estimates of physical activity, sedentary behavior, and sleep (collectively known as movement behaviors) in 3- and 4-year-old children worldwide remains uncertain. Objective: To report the proportion of 3- and 4-year-old children who met the World Health Organization guidelines for physical activity, sedentary behavior, and sleep across 33 countries. Design, Setting, and Participants: Pooled analysis of data from 14 cross-sectional studies (July 2008 to September 2022) identified through systematic reviews and personal networks. Thirty-three countries of varying income levels across 6 geographical regions. Each study site needed to have at least 40 children aged 3.0 to 4.9 years with valid accelerometry and parent-/caregiver-reported screen time and sleep duration data. Data were analyzed from October 2022 to February 2023. Exposures: Time spent in physical activity was assessed by reanalyzing accelerometry data using a harmonized data-processing protocol. Screen time and sleep duration were proxy reported by parents or caregivers. Main Outcomes and Measures: The proportion of children who met the World Health Organization guidelines for physical activity (≥180 min/d of total physical activity and ≥60 min/d of moderate- to vigorous-intensity physical activity), screen time (≤1 h/d), and sleep duration (10-13 h/d) was estimated across countries and by World Bank income group and geographical region using meta-analysis. Results: Of the 7017 children (mean [SD] age, 4.1 [0.5] years; 3585 [51.1%] boys and 3432 [48.9%] girls) in this pooled analysis, 14.3% (95% CI, 9.7-20.7) met the overall guidelines for physical activity, screen time, and sleep duration. There was no clear pattern according to income group: the proportion meeting the guidelines was 16.6% (95% CI, 10.4-25.3) in low- and lower-middle-income countries, 11.9% (95% CI, 5.9-22.5) in upper-middle-income countries, and 14.4% (95% CI, 9.6-21.1) in high-income countries. The region with the highest proportion meeting the guidelines was Africa (23.9%; 95% CI, 11.6-43.0), while the lowest proportion was in North and South America (7.7%; 95% CI, 3.6-15.8). Conclusions and Relevance: Most 3- and 4-year-old children in this pooled analysis did not meet the current World Health Organization guidelines for physical activity, sedentary behavior, and sleep. Priority must be given to understanding factors that influence these behaviors in this age group and to implementing contextually appropriate programs and policies proven to be effective in promoting healthy levels of movement behaviors.

The voices of children on movement behaviours: implications for promoting international guidelines to support obesity-prevention efforts.

BACKGROUND: As a key factor for the prevention of childhood obesity, WHO recommends a specific balance of movement behaviours (ie, physical activity, sedentary behaviour, and sleep) across the 24-h day for children younger than 5 years. Substantial evidence underpins our understanding of the benefits for healthy growth and development; however, little is known about young children's experiences and perceptions, and whether context-specific factors that might influence movement behaviours differ across the globe. METHODS: Acknowledging children's agency as knowledgeable informants on matters affecting their lives, children aged 3-5 years from communities and preschools in urban and rural Australia, Chile, China, India, Morocco, and South Africa, were interviewed. Discussions were based on a socioecological framework of the multifactorial, complex influences on young children's movement behaviours. Prompts were adapted to ensure relevance across diverse study sites. Ethics approval and guardian consent were obtained, and the Framework Method used for analysis. FINDINGS: 156 children (101 [65%] from urban areas, 55 [45%] from rural areas; 73 [47%] female, 83 [53%] male) shared their experiences, perceptions, and preferences related to movement behaviours and the barriers and enablers of outdoor play. Physical activity, sedentary behaviour, and to a lesser degree screen time occurred predominantly through play. Barriers to outdoor play included weather, air quality, and safety concerns. Sleep routines varied considerably and were influenced by room or bed sharing. Screen use was ubiquitous, presenting a challenge to meeting recommendations. The effect of daily structure, degree of autonomy, and interactions were consistent themes, and differences in how these factors influenced movement behaviours across study sites were evident. INTERPRETATION: The findings highlight that although movement behaviour guidelines are universal, contextual realities need to be considered in how socialisation and promotion of the guidelines are enacted. How young children's sociocultural and physical environments are constructed and influenced can foster or disrupt healthy movement behaviours, which might have implications for childhood obesity. FUNDING: Beijing High Level Talents Cultivation Project for Public Health Academic Leader; Beijing Medical Research Institute (Public service development and reform pilot project); British Academy for the Humanities and Social Sciences; KEM Hospital Research Centre; Ministry of Education and Universidad de La Frontera (Innovation in Higher Education Program); and National Health and Medical Research Council (Investigator Grant Leadership Fellow, Level 2).

Indispensable Amino Acid Digestibility of Moroccan Fava Bean Using the Dual Isotope Method in Healthy Adults.

BACKGROUND: Assessment of protein quality is necessary to satisfy the nutritional needs of populations across the world. In addition to indispensable amino acid (IAAs) composition, protein digestibility is a major component of IAA bioavailability, playing a crucial role in human health and affecting the linear growth of children. OBJECTIVES: This study aimed to evaluate IAA digestibility of fava beans, a legume widely consumed in Morocco using the dual-tracer method. METHODS: 2H-intrinsically labeled Fava beans supplemented with 12 mg/kg BW of 13C spirulina were given to 5 healthy volunteers (3 men and 2 women), aged 25.8 ± 3.3 y, with a mean BMI of 20.0 kg/m2. The meal was spread in small portions and was given hourly throughout 7 h. Blood was sampled at baseline and hourly from 5 to 8 h after meal ingestion. IAA digestibility was evaluated by gas chromatography-combustion-isotope ratio mass spectrometry using the 2H/13C ratio in plasma IAA. Digestible indispensable amino acid ratios (DIAAR) were calculated using the scoring pattern for people older than 3 y. RESULTS: Fava beans had an adequate level of lysine but were limiting in several IAAs, especially methionine. Under our experimental conditions, the average IAA digestibility of fava bean was 61.1% ± 5.2%. Valine had the highest digestibility (68.9% ± 4.3%) and threonine had the lowest (43.7% ± 8.2%). In consequence, the lowest DIAAR was 67% for threonine and only 47% for sulfur amino acids (SAA). CONCLUSIONS: The present study is the first to determine the digestibility of fava bean amino acids in humans. The mean IAA digestibility was moderate, and consequently, we conclude that fava bean provides a limited amount of several IAAs, especially SAA, but adequately for lysine. Preparation and cooking methods of fava beans should be improved to increase digestibility. This study was registered at ClinicalTrials.gov as NCT04866927.

Cut-point values for classifying active children and validity and reliability of physical activity questionnaire for children in Morocco.

BACKGROUND: The Physical Activity Questionnaire for Children (PAQ-C) is widely used to assess physical activity in populations; however, there is a lack of information about the psychometric properties (validity and reliability) and about the PAQ-C score meaning in populations from low-middle income countries. AIMS: The aim of this study is to evaluate the reliability and validity of PAQ-C and to determine the cut-point values of PAQ-C using accelerometry as a reference in a group of Moroccan children. METHODS: In a sample of 171 children and adolescents aged 8 to 14 years, physical activity was assessed with the GT3X + accelerometer and the PAQ-C. PAQ-C was administered for a second time (retest) after 1 week for a subsample (n = 73). Reliability was analyzed by intraclass correlation coefficient (ICC). The PAQ-C was compared against count per minute CPM and moderate to vigorous intensity PA (MVPA) obtained by accelerometry. Receiver operating curve analyses were performed to assess the performance of PAQ-C in identifying MVPA as measured by accelerometry (reference method). RESULTS: Test-retest reliability was poor with an ICC = (0.48 [0.27; 0.63] for the whole sample, while for the ≥11 year group, the intra-class correlation coefficient was moderate (0.71 [0.42; 0.86]. PAQ-C scores were significantly related to accelerometry-derived metrics of physical activity, CPM (R = 0.29, P < 0.001) and MVPA (R = 0.26, P < 0.001). For the age group ≥11 years, the associations between PAQ-C Scores and CPM and MVPA were stronger, respectively, R = 0.37 (P < 0.001), R = 0.38 (P < 0.0001). We identified that a PAQ-C Score cut-point of 2.33 (95%CI [0.43-0.68]) discriminated adequately between those who met physical activity guidelines and those that did not in the overall sample. CONCLUSIONS: The PAQ-C is valid and useful to assess population level physical activity in those ≥11 years in Morocco and so might be helpful in population surveillance of physical activity in Moroccan adolescents.

Status and Trends of Physical Activity Surveillance, Policy, and Research in 164 Countries: Findings From the Global Observatory for Physical Activity-GoPA! 2015 and 2020 Surveys.

BACKGROUND: Physical activity (PA) surveillance, policy, and research efforts need to be periodically appraised to gain insight into national and global capacities for PA promotion. The aim of this paper was to assess the status and trends in PA surveillance, policy, and research in 164 countries. METHODS: We used data from the Global Observatory for Physical Activity (GoPA!) 2015 and 2020 surveys. Comprehensive searches were performed for each country to determine the level of development of their PA surveillance, policy, and research, and the findings were verified by the GoPA! Country Contacts. Trends were analyzed based on the data available for both survey years. RESULTS: The global 5-year progress in all 3 indicators was modest, with most countries either improving or staying at the same level. PA surveillance, policy, and research improved or remained at a high level in 48.1%, 40.6%, and 42.1% of the countries, respectively. PA surveillance, policy, and research scores decreased or remained at a low level in 8.3%, 15.8%, and 28.6% of the countries, respectively. The highest capacity for PA promotion was found in Europe, the lowest in Africa and low- and lower-middle-income countries. Although a large percentage of the world's population benefit from at least some PA policy, surveillance, and research efforts in their countries, 49.6 million people are without PA surveillance, 629.4 million people are without PA policy, and 108.7 million live in countries without any PA research output. A total of 6.3 billion people or 88.2% of the world's population live in countries where PA promotion capacity should be significantly improved. CONCLUSION: Despite PA is essential for health, there are large inequalities between countries and world regions in their capacity to promote PA. Coordinated efforts are needed to reduce the inequalities and improve the global capacity for PA promotion.

Variation in human water turnover associated with environmental and lifestyle factors.

Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking (2H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.

Human total, basal and activity energy expenditures are independent of ambient environmental temperature.

Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (-10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average Ta and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p < 0.01) relationships between TEE, BEE and Ta emerged in females but the effect sizes were not biologically meaningful. Temperatures inside buildings are regulated at 18-25°C independent of latitude. Hence, adults in the US modify their environments to keep TEE constant across a wide range of external ambient temperatures.

Levels and Correlates of Objectively Measured Sedentary Behavior in Young Children: SUNRISE Study Results from 19 Countries.

PURPOSE: There is a paucity of global data on sedentary behavior during early childhood. The purpose of this study was to examine how device-measured sedentary behavior in young children differed across geographically, economically, and sociodemographically diverse populations, in an international sample. METHODS: This multinational, cross-sectional study included data from 1071 children 3-5 yr old from 19 countries, collected between 2018 and 2020 (pre-COVID). Sedentary behavior was measured for three consecutive days using activPAL accelerometers. Sedentary time, sedentary fragmentation, and seated transport duration were calculated. Linear mixed models were used to examine the differences in sedentary behavior variables between sex, country-level income groups, urban/rural settings, and population density. RESULTS: Children spent 56% (7.4 h) of their waking time sedentary. The longest average bout duration was 81.1 ± 45.4 min, and an average of 61.1 ± 50.1 min·d-1 was spent in seated transport. Children from upper-middle-income and high-income countries spent a greater proportion of the day sedentary, accrued more sedentary bouts, had shorter breaks between sedentary bouts, and spent significantly more time in seated transport, compared with children from low-income and lower-middle-income countries. Sex and urban/rural residential setting were not associated with any outcomes. Higher population density was associated with several higher sedentary behavior measures. CONCLUSIONS: These data advance our understanding of young children's sedentary behavior patterns globally. Country income levels and population density appear to be stronger drivers of the observed differences, than sex or rural/urban residential setting.

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.

Cross-sectional examination of 24-hour movement behaviours among 3- and 4-year-old children in urban and rural settings in low-income, middle-income and high-income countries: the SUNRISE study protocol.

INTRODUCTION: 24-hour movement behaviours (physical activity, sedentary behaviour and sleep) during the early years are associated with health and developmental outcomes, prompting the WHO to develop Global guidelines for physical activity, sedentary behaviour and sleep for children under 5 years of age. Prevalence data on 24-hour movement behaviours is lacking, particularly in low-income and middle-income countries (LMICs). This paper describes the development of the SUNRISE International Study of Movement Behaviours in the Early Years protocol, designed to address this gap. METHODS AND ANALYSIS: SUNRISE is the first international cross-sectional study that aims to determine the proportion of 3- and 4-year-old children who meet the WHO Global guidelines. The study will assess if proportions differ by gender, urban/rural location and/or socioeconomic status. Executive function, motor skills and adiposity will be assessed and potential correlates of 24-hour movement behaviours examined. Pilot research from 24 countries (14 LMICs) informed the study design and protocol. Data are collected locally by research staff from partnering institutions who are trained throughout the research process. Piloting of all measures to determine protocol acceptability and feasibility was interrupted by COVID-19 but is nearing completion. At the time of publication 41 countries are participating in the SUNRISE study. ETHICS AND DISSEMINATION: The SUNRISE protocol has received ethics approved from the University of Wollongong, Australia, and in each country by the applicable ethics committees. Approval is also sought from any relevant government departments or organisations. The results will inform global efforts to prevent childhood obesity and ensure young children reach their health and developmental potential. Findings on the correlates of movement behaviours can guide future interventions to improve the movement behaviours in culturally specific ways. Study findings will be disseminated via publications, conference presentations and may contribute to the development of local guidelines and public health interventions.

Physical activity and fat-free mass during growth and in later life.

BACKGROUND: Physical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass. OBJECTIVES: A study is presented of the association between FFM and physical activity in relation to age. METHODS: In a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution. RESULTS: PAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males < 18 y old, and 32% and 47% of the variation in FFM in females and males ≥ 18 y old, respectively. In participants < 18 y old, mean FM-adjusted FFM was 1.7 kg (95% CI: 0.1, 3.2 kg) and 3.4 kg (95% CI: 1.0, 5.6 kg) higher in a very active participant with PAL = 2.0 than in a sedentary participant with PAL = 1.5, for females and males, respectively. At age 18 y, height and FM-adjusted FFM was 3.6 kg (95% CI: 2.8, 4.4 kg) and 4.4 kg (95% CI: 3.2, 5.7 kg) higher, and at age 80 y 0.7 kg (95% CI: -0.2, 1.7 kg) and 1.0 kg (95% CI: -0.1, 2.1 kg) higher, in a participant with PAL = 2.0 than in a participant with PAL = 1.5, for females and males, respectively. CONCLUSIONS: If these associations are causal, they suggest physical activity is a major determinant of body composition as reflected in peak FFM, and that a physically active lifestyle can only partly protect against loss of FFM in aging adults.

Daily energy expenditure through the human life course.

Total daily energy expenditure ("total expenditure") reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. Total expenditure increased with fat-free mass in a power-law manner, with four distinct life stages. Fat-free mass-adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults. These changes shed light on human development and aging and should help shape nutrition and health strategies across the life span.

Energy compensation and adiposity in humans.

Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1-3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response-energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity.

Global effect of COVID-19 pandemic on physical activity, sedentary behaviour and sleep among 3- to 5-year-old children: a longitudinal study of 14 countries.

BACKGROUND: The restrictions associated with the 2020 COVID-19 pandemic has resulted in changes to young children's daily routines and habits. The impact on their participation in movement behaviours (physical activity, sedentary screen time and sleep) is unknown. This international longitudinal study compared young children's movement behaviours before and during the COVID-19 pandemic. METHODS: Parents of children aged 3-5 years, from 14 countries (8 low- and middle-income countries, LMICs) completed surveys to assess changes in movement behaviours and how these changes were associated with the COVID-19 pandemic. Surveys were completed in the 12 months up to March 2020 and again between May and June 2020 (at the height of restrictions). Physical activity (PA), sedentary screen time (SST) and sleep were assessed via parent survey. At Time 2, COVID-19 factors including level of restriction, environmental conditions, and parental stress were measured. Compliance with the World Health Organizations (WHO) Global guidelines for PA (180 min/day [≥60 min moderate- vigorous PA]), SST (≤1 h/day) and sleep (10-13 h/day) for children under 5 years of age, was determined. RESULTS: Nine hundred- forty-eight parents completed the survey at both time points. Children from LMICs were more likely to meet the PA (Adjusted Odds Ratio [AdjOR] = 2.0, 95%Confidence Interval [CI] 1.0,3.8) and SST (AdjOR = 2.2, 95%CI 1.2,3.9) guidelines than their high-income country (HIC) counterparts. Children who could go outside during COVID-19 were more likely to meet all WHO Global guidelines (AdjOR = 3.3, 95%CI 1.1,9.8) than those who were not. Children of parents with higher compared to lower stress were less likely to meet all three guidelines (AdjOR = 0.5, 95%CI 0.3,0.9). CONCLUSION: PA and SST levels of children from LMICs have been less impacted by COVID-19 than in HICs. Ensuring children can access an outdoor space, and supporting parents' mental health are important prerequisites for enabling pre-schoolers to practice healthy movement behaviours and meet the Global guidelines.

A standard calculation methodology for human doubly labeled water studies.

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (<10 kg). Using data for 1,021 babies and infants, we show that the DSR varies non-linearly with body mass between 0 and 10 kg. Using this relationship to predict DSR from weight provides an equation for rCO2 over this size range that agrees well with indirect calorimetry (average difference 0.64%; SD = 12.2%). We propose adoption of these equations in future studies.

Effects of Breastfeeding on Maternal Body Composition in Moroccan Lactating Women during Twelve Months after Birth Using Stable Isotopic Dilution Technique.

BACKGROUND: Exclusive breastfeeding during the first six months of an infant's life is an important factor for their optimal growth and health. Breastfeeding also has maternal benefits and can assist with postpartum weight loss. As shown by previous studies, postpartum weight retention can contribute to obesity. OBJECTIVE: To quantify the human milk and evaluate the effect of breastfeeding on maternal weight loss during the 12 months postpartum. METHOD: This study included 70-mother-baby pairs. Infants' intake of human milk and water from other sources, as well as the body composition of the mothers, were measured at the 1st, 3rd, 6th, 9th and 12th month postpartum by using the deuterium oxide dose-to-mother technique. RESULTS: There was a significant change in the mothers' body composition between the first and twelfth months in exclusive breastfeeding women compared to not-exclusive ones. Similarly, the difference between the quantities of human milk intake was highly significant in exclusive breastfeeding women compared to women who were not exclusively breastfeeding. CONCLUSION: Our results showed that exclusive breastfeeding for twelve months has a significant effect on postpartum weight loss among Moroccan women and that it is an effective way to control overweight and obesity among lactating women.

Combined consumption of a single high-dose vitamin A supplement with provision of vitamin A fortified oil to households maintains adequate milk retinol concentrations for 6 months in lactating Moroccan women.

In Morocco, postpartum women systematically receive a single, high dose of vitamin A (VA; 200 000 IU) within the first month of giving birth and vegetable oil is fortified to increase the VA intake. The efficacy of this combined approach of supplementation and fortification for increasing maternal VA status during lactation is not known. The purpose of the study is to evaluate the effect of postpartum high dose VA supplementation and provision of VA fortified oil for household consumption on plasma and milk retinol concentrations of lactating Moroccan women during the first 6 months after giving birth. Postpartum women aged 19-40 years received a VA supplement and thereafter were randomly assigned to one of two groups to receive weekly vitamin A fortified oil (FO) or non-fortified oil (NFO) for 6 months. Serum retinol concentration was higher in the FO group than in the NFO group at 6 months after giving birth (p < 0.0001). Milk retinol per gram fat at baseline did not differ by group; by 3 months after giving birth, milk retinol per gram fat was higher in the FO group than in the NFO group (p = 0.02) and remained higher throughout the 6 months (p < 0.0001). The combination of supplementation and fortification has a more sustained impact on milk retinol concentrations than supplementation alone, which did not have a sustained impact on milk VA concentrations. The fortification approach seems to be more effective for maintaining adequate milk VA concentrations among lactating Moroccan women. Fortification seems to be a long-term solution for the problem of VA deficiency, especially among women in low-income communities.