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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.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

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

Childhood undernutrition is a major health burden worldwide that increases childhood morbidity and mortality and causes impairment in infant growth and developmental delays that can persist into adulthood. The first weeks and months after birth are critical to the establishment of healthy growth and development during childhood. The World Health Organization recommends immediate and exclusive breastfeeding (EBF). In infants for whom EBF may not meet nutritional and caloric demands, early, daily, small-volume formula supplementation along with breastfeeding may more effectively avoid underweight wasting and stunting in early infancy than breastfeeding alone. The primary objective of this randomized controlled trial is to evaluate the efficacy of formula for 30 days among low birth weight (LBW) infants

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.

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

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.

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.

Breastfeeding is the gold standard for feeding infants because of its long-term benefits to health and development, but most infants in the United States are not exclusively breastfed in the first six months. We enrolled 24 infants who were either exclusively breastfed or supplemented with formula by the age of one month. We collected diet information, stool samples for evaluation of microbiotas by 16S rRNA sequencing, and blood samples for assessment of immune development by flow cytometry from birth to 6 months of age. We further typed the Bifidobacterium strains in stool samples whose 16S rRNA sequencing showed the presence of Bifidobacteriaceae. Supplementation with formula during breastfeeding transiently changed the composition of the gut microbiome, but the impact dissipated by six months of age. For example, Bifidobacterium longum, a bacterial species highly correlated with human milk consumption, was found to be significantly different only at 1 month of age but not at later time points. No immunologic differences were found to be associated with supplementation, including the development of T-cell subsets, B cells, or monocytes. These data suggest that early formula supplementation, given in addition to breast milk, has minimal lasting impact on the gut microbiome or immunity.

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 (

The extent to which early weight loss in behavioral weight control interventions predicts long-term success remains unclear. In this study, we developed an algorithm aimed at classifying weight change trajectories and examined its ability to predict long-term weight loss based on weight early change. We utilized data from 667 de-identified individuals who participated in a commercial weight loss program (Instinct Health Science), comprising 69,363 weight records. Sequential polynomial regression models were employed to classify participants into distinct weight trajectory patterns based on key model parameters. Next, we applied multinomial logistic models to evaluate if early weight loss in the first 14 days and prolonged duration of participation were significantly associated with long-term weight loss patterns. The mean percentage of weight loss was 7.9 ± 5.1% over 133 ± 69 days. Our analysis revealed four main weight loss trajectory patterns: a steady decrease over time (30.6%), a decrease to a plateau with subsequent decline (15.8%), a decrease to a plateau with subsequent increase (46.9%), and no substantial decrease (6.7%). Early weight change rate and total participating duration emerged as significant factors in differentiating long-term weight loss patterns. These findings contribute to support the provision of tailored advice in the early phase of behavioral interventions for weight loss. [ABSTRACT FROM AUTHOR]

Lifestyle programs that reduce health risks and support weight loss (WL) in older adults face adherence and attendance challenges due to reduced energy requirements, impaired mobility, lack of transportation, and low social support. Tailored lifestyle and weight management programs are needed to better support healthy aging for older adults. Here, we developed and piloted an age-adapted, remotely delivered modification of the Diabetes Prevention Program (DPP). The modification includes age-appropriate goals, visuals, and examples; flexible dietary composition; remote classroom and fitness-monitoring technology; and standardized online classroom materials employing pedagogical and behavior change theory. The modifications were designed to safeguard fidelity and to boost adherence, engagement, and knowledge integration, with the convenience of a fully remote WL program for diverse older adults. Six-month pilot data are presented from older adults (55–85 years, body mass index (BMI) 27–39.9 kg/m2, N = 20) randomly allocated to an online DPP intervention with weight, diet, and activity monitored remotely, or into a waitlisted control. The intervention achieved 100% attendance and adherence to self-monitoring. The intervention group mean (±SD) body weight change was −9.5% (±4.1); 90% lost ≥ 5%. By contrast, the control group gained 2.4% (±1.8). Once thought incompatible with older adults, remote interventions are feasible for older adults and can support fidelity, adherence, engagement, and clinically significant WL. Standardized materials are provided for future implementation. [ABSTRACT FROM AUTHOR]

BackgroundExcess energy intake from meals consumed away from home is implicated as a major contributor to obesity, and ∼50% of US restaurants are individual or small-chain (non-chain) establishments that do not provide nutrition information.ObjectiveTo measure the energy content of frequently ordered meals in non-chain restaurants in three US locations, and compare with the energy content of meals from large-chain restaurants, energy requirements, and food database information.DesignA multisite random-sampling protocol was used to measure the energy contents of the most frequently ordered meals from the most popular cuisines in non-chain restaurants, together with equivalent meals from large-chain restaurants.SettingMeals were obtained from restaurants in San Francisco, CA; Boston, MA; and Little Rock, AR, between 2011 and 2014.Main outcome measuresMeal energy content determined by bomb calorimetry.Statistical analysis performedRegional and cuisine differences were assessed using a mixed model with restaurant nested within region×cuisine as the random factor. Paired t tests were used to evaluate differences between non-chain and chain meals, human energy requirements, and food database values.ResultsMeals from non-chain restaurants contained 1,205±465 kcal/meal, amounts that were not significantly different from equivalent meals from large-chain restaurants (+5.1%; P=0.41). There was a significant effect of cuisine on non-chain meal energy, and three of the four most popular cuisines (American, Italian, and Chinese) had the highest mean energy (1,495 kcal/meal). Ninety-two percent of meals exceeded typical energy requirements for a single eating occasion.ConclusionsNon-chain restaurants lacking nutrition information serve amounts of energy that are typically far in excess of human energy requirements for single eating occasions, and are equivalent to amounts served by the large-chain restaurants that have previously been criticized for providing excess energy. Restaurants in general, rather than specific categories of restaurant, expose patrons to excessive portions that induce overeating through established biological mechanisms.

It is estimated that more than 170 million people are infected with hepatitis C virus (HCV) worldwide (1,2). Clinical trials have demonstrated that, for the first time in human history, [...]

I. Introduction II. Changes in the Regulation of Energy Intake A. Comparisons of young and elderly adults B. Reduced hunger and increased satiation as mediators of impaired defense against energy [...]

The relative contribution of circulating glucose to meal-to-meal variability in energy intake is not known. In 8 free-living young (median age 26.5 y) women with healthy body weight (median BMI 22.2 kg/[m.sup.2]), we measured glucose in the interstitial space by an automated monitoring procedure (continuous glucose monitoring system, CGMS[TM]) for up to 3 consecutive days (mean 706 glucose readings per subject). We examined the association between interstitial glucose (which lags blood glucose by ~10 min), self-reported hunger, satiety, desire for a meal, and nutrient intakes. Participants reported consuming a typical Western diet (59% carbohydrate, 27% fat, 14% protein). Median (interquartile range) interstitial glucose was 5.2 mmol/L (4.7-5.8). Using repeated-measures techniques in univariate analyses, desire for a meal (r = 0.45, P < 0.0001), hunger (r = 0.37, P = 0.0002), satiety (r = -0.40, P < 0.0001), low interstitial absolute mean glucose up to 25 min before eating (r = -0.23, P = 0.02), and a large decline in glucose between 40 and 5 min before eating (r = -0.17, P = 0.08) were all associated with meal energy intake. In multivariate regression analyses, desire for a meal (P < 0.0001) and hunger (P = 0.02) were the strongest independent contributors to meal energy intake, whereas absolute mean glucose measured in the period 15 to 0 min before eating was marginally significant (P = 0.08). In conclusion, absolute glucose level is a significant predictor of energy intake in nonobese women. However, desire for a meal and hunger are quantitatively more important, emphasizing the importance of both glucose signals and nonglucose (internal or environmental) factors in within-subject variability in energy intake. In addition, the CGMS may have utility in understanding the role of circulating glucose in energy regulation in free-living subjects under a wide range of different nutritional conditions. KEY WORDS: * glucose * energy * hunger * satiety * free-living

To test the hypothesis that total energy expenditure (TEE) and resting energy expenditure (REE) are low in extremely obese individuals, factors that could contribute to maintenance of excess weight, a cross-sectional study was conducted in 30 weight stable, extremely obese women [BMI (mean [+ or -] SEM) 48.9 [+ or -] 1.7 kg/[m.sup.2]]. TEE was measured over 14 d using the doubly labeled water method, REE and the thermic effect of feeding (IEF) were measured using indirect calorimetry, and activity energy expenditure (AEE) was calculated as TEE--(REE + TEF). Body composition was determined using a 3-compartment model. Subjects were divided into tertiles of BMI (37.5-45.0; 45.1-52.0; and 52.1-77.0 kg/[m.sup.2]) for data analysis. TEE and REE increased with increasing BMI tertile: TEE, 12.80 [+ or -] 0.5, 14.67 [+ or -] 0.5, and 16.10 [+ or -] 0.9 MJ/d (P < 0.01); REE, 7.87 [+ or -] 0.2, 8.78 [+ or -] 0.3, and 9.94 [+ or -] 0.6 MJ/d (P < 0.001), and these values were 29-38% higher than published means of measured TEE in nonobese individuals. No significant differences were observed among BMI tertiles for AEE, TEF, or physical activity level (PAL = TEE/REE, overall mean 1.64 [+ or -] 0.16). The Harris-Benedict and WHO equations provided the closest estimates of REE (within 3%), whereas the obese-specific equations of Ireton-Jones overpredicted (40%) and Bernstein underpredicted (21%) REE. Extremely obese individuals have high absolute values for TEE and REE, indicating that excess energy intake contributes to the maintenance of excess weight. Standard equations developed for nonobese populations provided the most accurate estimates of REE for the obese individuals studied here. REE was not accurately predicted by equations developed in obese populations. J. Nutr. 134: 1412-1416, 2004. KEY WORDS: * extreme obesity * energy expenditure * fat-free mass * prediction equations

To identify existing dietary patterns and examine associations between these patterns and plasma homocysteine and B vitamin concentrations in an urban Chinese population living in Beijing (n = 119), dietary information was collected with a food frequency questionnaire designed for this population. Plasma homocysteine and B vitamin concentrations were examined. Food group variables, expressed as percentages of total energy intake, were entered into cluster analysis to define three distinct dietary pattern groups. The prevalence of high homocysteine (>11 [micro]mol/L for women and 12 [micro]mol/L for men), was 31.9%; of low folate ( KEY WORDS: * dietary patterns * homocysteine * B vitamin * cluster analysis * Chinese

Little is known about the relative effects of fermentable fiber (FF) vs. nonfermentable fiber (NFF) on energy regulation in humans. We compared 27 [+ or -] 0.6 g/d supplements of FF (pectin,/[beta]-glucan) and NFF (methylcellulose) for their ability to decrease ad libitum energy intake (El) and hunger, increase satiety and cause spontaneous body weight and fat losses. Men and women (n = 11) aged 23-46 y, BMI 20.0-34.4 kg/[m.sup.2], consumed first NFF and then FF for 3 wk each, with a 4-wk washout period between phases. Daily satiety assessed with analog scales was higher with NFF than FF (60.7 [+ or -] 1.0 vs. 57.7 [+ or -] 0.8 mm, P = 0.01). However, there were no differences in reported El (NFF < FF by 7%, P = 0.31, NFF < baseline by 9.5%, P = 0.11), body weight (NFF 0.13 kg, P = 0.73; FF 0.13 kg, P = 0.60) or fat percentage (NFF -0.3%, P = 0.56; FF -0.1%, P = 0.66) within either phase. In contrast to findings in animals, NFF was more, rather than less satiating than FF, and use of neither NFF nor FF preparations was associated with body weight or fat loss. These pilot results suggest no role for short-term use of FF and NFF supplements in promoting weight loss in humans consuming a diet ad libitum. J. Nutr. 133: 3141-3144, 2003. KEY WORDS: * fiber * fermentable * nonfermentable * satiety * weight loss

U.S. adults are now gaining more weight and becoming obese at an earlier age than in previous years. The specific causes of adult weight gain are unknown, but may be attributed to a combination of factors leading to positive energy balance. U.S. food supply data indicate that Americans have had a gradual increase in energy intake since 1970, and that per capita energy intake was 1.42 MJ/d (340 kcal/d) higher in 1994 than that in 1984. In contrast, self-reported physical activity remained constant between 1990 and 1998. Taken together, these data indicate that the increasing trend in U.S. adult weight gain is primarily attributable to overconsumption of energy. Epidemiological and experimental studies in animals and humans provide strong evidence that biobehavioral factors such as dietary variety, liquid (vs. solid) energy, portion size, palatability (taste), snacking patterns, restaurant and other away-from-home food, and dietary restraint and disinhibition influence hunger, satiety and/or voluntary energy intake. When these eating behaviors are consistently experienced either separately or in combination over the long term, they are likely to facilitate overeating. We provide a brief overview of the evidence to date for the role of these biobehavioral factors in contributing to excess energy intake and increases in body weight over time. J. Nutr. 132: 3830S-3834S, 2002. KEY WORDS: * obesity * weight gain * energy intake * energy balance * biobehavioral factors

There is little information on the accuracy of simple body composition methods in non-Western populations. We determined the percentage of body fat (%BF) by isotope dilution [oxygen-18 ([H.sub.2][sup.18]O) and deuterium oxide ([sup.2][H.sub.2]O)] and anthropometry in 71 healthy, urban Chinese adults aged 35-49 y [body mass index (BMI) 18-35 kg/[m.sup.2]]. The accuracy of several prediction equations for assessment of %BF from skinfold measurements was evaluated against %BF determined by [H.sub.2][sup.18]O dilution. We also assessed the relationship between BMI and %BF, and the fat-free mass (FFM) hydration coefficient for our population. All skinfold equations yielded means within ~2%BF of [H.sub.2][sup.18]O-derived %BF. However, on the basis of residual plot analysis and the 95% confidence interval (Cl) for the mean difference between methods, the equations of Durnin and Womersley (for assessment of body density from skinfolds) coupled with that of Brozek et al. (for assessment of %BF from body density) provided the most valid assessment for individuals. In addition, the FFM hydration coefficient averaged 0.734 [+ or -] 0.002 (SEM), indicating that the usually assumed value of 0.732 is appropriate for this population. Finally, although BMI had high specificity (90%) for classifying individuals as having body fat within the normal range (30%BF. J. Nutr. 132: 310-317, 2002. KEY WORDS: * isotope dilution * anthropometry * body mass index * percentage of body fat * fat-free mass hydration coefficient