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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., Competing Interests: Conflicts of interest The authors have no conflicts of interest to declare., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

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., (© 2022. The Author(s).)

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., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

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 rCO 2 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 rCO 2 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., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Background: The effect of whole grains on the regulation of energy balance remains controversial. Objective: We aimed to determine the effects of substituting whole grains for refined grains, independent of body weight changes, on energy-metabolism metrics and glycemic control. Design: The study was a randomized, controlled, parallel-arm controlled-feeding trial that was conducted in 81 men and postmenopausal women [49 men and 32 women; age range: 40-65 y; body mass index (in kg/m 2 ): <35.0]. After a 2-wk run-in period, participants were randomly assigned to consume 1 of 2 weight-maintenance diets for 6 wk. Diets differed in whole-grain and fiber contents [mean ± SDs: whole grain-rich diet: 207 ± 39 g whole grains plus 40 ± 5 g dietary fiber/d; refined grain-based diet: 0 g whole grains plus 21 ± 3 g dietary fiber/d] but were otherwise similar. Energy metabolism and body-composition metrics, appetite, markers of glycemic control, and gut microbiota were measured at 2 and 8 wk. Results: By design, body weight was maintained in both groups. Plasma alkylresorcinols, which are biomarkers of whole-grain intake, increased in the whole grain-rich diet group (WG) but not in the refined grain-based diet group (RG) ( P -diet-by-time interaction < 0.0001). Beta ± SE changes (ΔWG compared with ΔRG) in the resting metabolic rate (RMR) (43 ± 25 kcal/d; P = 0.04), stool weight (76 ± 12 g/d; P < 0.0001), and stool energy content (57 ± 17 kcal/d; P = 0.003), but not in stool energy density, were higher in the WG. When combined, the favorable energetic effects in the WG translated into a 92-kcal/d (95% CI: 28, 156-kcal/d) higher net daily energy loss compared with that of the RG ( P = 0.005). Prospective consumption ( P = 0.07) and glycemia after an oral-glucose-tolerance test ( P = 0.10) trended toward being lower in the WG than in the RG. When nonadherent participants were excluded, between-group differences in stool energy content and glucose tolerance increased, and between-group differences in the RMR and prospective consumption were not statistically significant. Conclusion: These findings suggest positive effects of whole grains on the RMR and stool energy excretion that favorably influence energy balance and may help explain epidemiologic associations between whole-grain consumption and reduced body weight and adiposity. This trial was registered at clinicaltrials.gov as NCT01902394., (© 2017 American Society for Nutrition.)

Childhood cancer survivors are at an increased risk of obesity but causes for this elevated risk are uncertain. We evaluated total energy expenditure in childhood cancer survivors using the doubly labeled water method in a cross-sectional study of 17 survivors of pediatric leukemia or lymphoma (median age, 11.5 y). Mean total energy expenditure was 2073 kcal/d, which was nearly 500 kcal/d lower than estimated energy requirements with recommended levels of physical activity. This energy gap is likely to contribute to the risk of obesity in this population and future trials are needed to assess implications and potential treatment strategies.

The role of dietary energy density (ED) in the regulation of energy intake (EI) is controversial. Methodologically, there is also debate about whether beverages should be included in dietary ED calculations. To address these issues, studies examining the effects of ED on EI or body weight in nonelderly adults were reviewed. Different approaches to calculating dietary ED do not appear to alter the direction of reported relations between ED and body weight. Evidence that lowering dietary ED reduces EI in short-term studies is convincing, but there are currently insufficient data to determine long-term effectiveness for weight loss. The review also identified key barriers to progress in understanding the role of ED in energy regulation, in particular the absence of a standard definition of ED, and the lack of data from multiple long-term clinical trials examining the effectiveness of low-ED diet recommendations for preventing both primary weight gain and weight regain in nonobese individuals. Long-term clinical trials designed to examine the impact of dietary ED on energy regulation, and including multiple ED calculation methods within the same study, are still needed to determine the importance of ED in the regulation of EI and body weight., (© 2014 American Society for Nutrition.)

While short-term studies demonstrate consistent effects of dietary protein, fiber, glycemic index and energy density on energy intake, long-term effectiveness trials typically indicate small or non-significant effects of these dietary factors on long-term weight change. In consequence, most lifestyle interventions for weight control typically focus on a single dietary factor, such as low energy density, to achieve reductions in energy intake. This paper proposes a multiple-dietary-factor model for the effects of dietary factors on energy intake and the regulation of energy balance that assumes additive effects of different dietary factors. The model is consistent with emerging evidence from recent studies examining pairs of dietary factors. Randomized clinical trials are now needed to determine whether multiple-dietary-factor prescriptions combined with standard behavior modification techniques lead to improved sustainability of weight loss in lifestyle interventions compared to conventional single-dietary-factor prescriptions., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reproducibility of the DLW method using 2 protocols developed and implemented in a multicenter clinical trial-the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE). To document the longitudinal reproducibility of the DLW method, 2 protocols, 1 based on repeated analysis of dose dilutions over the course of the clinical trial (dose-dilution protocol) and 1 based on repeated but blinded analysis of randomly selected DLW studies (test-retest protocol), were carried out. The dose-dilution protocol showed that the theoretical fractional turnover rates for (2)H and (18)O and the difference between the 2 fractional turnover rates were reproducible to within 1% and 5%, respectively, over 4.5 y. The Bland-Altman pair-wise comparisons of the results generated from 50 test-retest DLW studies showed that the fractional turnover rates and isotope dilution spaces for (2)H and (18)O, and total energy expenditure, were highly reproducible over 2.4 y. Our results show that the DLW method is reproducible in longitudinal studies and confirm the validity of this method to measure energy expenditure, define energy intake prescriptions, and monitor adherence and body composition changes over the period of 2.5-4.4 y. The 2 protocols can be adopted by other laboratories to document the longitudinal reproducibility of their measurements to ensure the long-term outcomes of interest are meaningful biologically. This trial was registered at clinicaltrials.gov as NCT00427193.

The United States population is aging rapidly, and understanding the potential impact and feasibility of lifestyle interventions on the aging process is of central importance for addressing future population health and health care costs. This symposium addressed the question of whether caloric restriction may be a feasible strategy to improve human health by reductions in rates of primary and secondary aging in humans, viewed from the perspective of existing data in animal models, and by using emerging data from the human Comprehensive Assessment of Long-Term Reduction in Energy Intake trial, which is a randomized trial of human caloric restriction in free-living men and women.

Calorie restriction (CR) is a component of most weight loss interventions and a potential strategy to slow aging. Accurate determination of energy intake and %CR is critical when interpreting the results of CR interventions; this is most accurately achieved using the doubly labeled water method to quantify total energy expenditure (TEE). However, the costs and analytical requirements of this method preclude its repeated use in many clinical trials. Our aims were to determine 1) the optimal TEE assessment time points for quantifying average energy intake and %CR during long-term CR interventions and 2) the optimal approach for quantifying short-term changes in body energy stores to determine energy intake and %CR during 2-wk DLW periods. Adults randomized to a CR intervention in the multicenter CALERIE study underwent measurements of TEE by doubly labeled water and body composition at baseline and months 1, 3, and 6. Average %CR achieved during the intervention was 24.9 ± 8.7%, which was computed using an approach that included four TEE assessment time points (i.e., TEE(baseline, months 1, 3, and 6)) plus the 6-mo change in body composition. Approaches that included fewer TEE assessments yielded %CR values of 23.4 ± 9.0 (TEE(baseline,) months 3 and 6), 25.0 ± 8.7 (TEE(baseline,) months 1 and 6), and 20.9 ± 7.1% (TEE(baseline, month 6)); the latter approach differed significantly from approach 1 (P < 0.001). TEE declined 9.6 ± 9.9% within 2-4 wk of CR beginning and then stabilized. Regression of daily home weights provided the most reliable estimate of short-term change in energy stores. In summary, optimal quantification of energy intake and %CR during weight loss necessitates a TEE measurement within the first month of CR to capture the rapid reduction in TEE.

The relative importance of eating frequency to weight control is poorly understood. This review examines the evidence to date on the role of eating frequency in weight control in free-living adults. The majority of cross-sectional studies in free-living adults show an inverse relationship between eating frequency and adiposity; however, this is likely an artifact produced by the underreporting of eating frequency concurrent with underreporting of energy intake. When implausible energy intake reporting (which is mostly underreporting) is taken into account, the association between eating frequency and adiposity becomes positive. In studies in which eating frequency is prescribed and food intake is mostly self-selected, there is either no effect or a minor positive effect of eating frequency on energy intake. Most of those studies have been short-term and lack the necessary dietary biomarkers to validate reported energy intakes and eating frequencies. In conclusion, there is some suggestion from cross-sectional studies in which energy intake underreporting is taken into account and from experimental studies to date that greater eating frequency may promote positive energy balance. However, experimental studies of longer-term duration that include objective dietary biomarkers are necessary before firm conclusions about the relative importance of eating frequency in weight control can be made.

Background: There remains no consensus about the optimal dietary composition for sustained weight loss., Objective: The objective was to examine the effects of 2 dietary macronutrient patterns with different glycemic loads on adherence to a prescribed regimen of calorie restriction (CR), weight and fat loss, and related variables., Design: A randomized controlled trial (RCT) of diets with a high glycemic load (HG) or a low glycemic load (LG) at 30% CR was conducted in 34 healthy overweight adults with a mean (+/-SD) age of 35 +/- 6 y and body mass index (kg/m(2)) of 27.6 +/- 1.4. All food was provided for 6 mo in diets controlled for confounding variables, and subjects self-administered the plans for 6 additional months. Primary and secondary outcomes included energy intake measured by doubly labeled water, body weight and fatness, hunger, satiety, and resting metabolic rate., Results: All groups consumed significantly less energy during CR than at baseline (P < 0.01), but changes in energy intake, body weight, body fat, and resting metabolic rate did not differ significantly between groups. Both groups ate more energy than provided (eg, 21% and 28% CR at 3 mo and 16% and 17% CR at 6 mo with HG and LG, respectively). Percentage weight change at 12 mo was -8.04 +/- 4.1% in the HG group and -7.81 +/- 5.0% in the LG group. There was no effect of dietary composition on changes in hunger, satiety, or satisfaction with the amount and type of provided food during CR., Conclusions: These findings provide more detailed evidence to suggest that diets differing substantially in glycemic load induce comparable long-term weight loss.

Changes in energy regulation occur during normal aging and contribute to the common phenomenon of weight and fat losses late in life. This review synthesizes data on aging-related changes in energy intake and energy expenditure and on the regulation of energy intake and expenditure. The ability of older adults to accurately regulate energy intake is impaired, with a number of possible explanations including delayed rate of absorption of macronutrients secondary to reductions in taste and smell acuity and numerous hormonal and metabolic mediators of energy regulation that change with aging. There are also changes in patterns of dietary intake and a reduction in the variety of foods consumed in old age that are thought to further reduce energy intake. Additionally, all components of energy expenditure decrease with aging, in particular energy expenditure for physical activity and basal metabolic rate, and the ability of energy expenditure to increase or decrease to attenuate energy imbalance during overeating or undereating also decreases. Combined, these changes result in an increased susceptibility to energy imbalance (both positive and negative) in old age that is associated with deteriorations in health. Practical interventions for prevention of weight and fat fluctuations in old age are anticipated here based on emerging knowledge of the role of such factors as dietary variety, taste, and palatability in late-life energy regulation.

Objective: To summarise the literature on energy requirements and aging., Design: An analysis and review of published data on components of energy expenditure and total energy expenditure (TEE)., Setting: Data on basal metabolic rate (BMR) and TEE were obtained from the US Institute of Medicine of the National Academies database (all available data from studies published before 2001, collected from 20 researchers willing to provide individual subject results)., Subjects: Those individuals from the database who were 20-100 years of age., Results: TEE and physical activity level (PAL, defined as the ratio of total to resting energy expenditure) declined progressively throughout adult life in both normal weight and overweight men and women. In normal weight individuals (defined as body mass index (BMI) 18.5-25.0 kg m(-2)) TEE fell by approximately 150 kcal per decade, and PAL fell from an average of 1.75 in the second decade of life to 1.28 in the ninth decade. Thermic effect of feeding data from other published studies indicated no consistent change associated with aging., Conclusions: Aging is associated with progressive declines in resting and TEE, which have implications for defining dietary energy requirements at different stages of adult life.

Background: Low body mass index (BMI) and micronutrient deficiencies are associated with increased morbidity and mortality rates in old age. Whether adverse patterns of dietary variety predict both low BMI and low micronutrient intakes in older adults was investigated., Methods: A cross-sectional analysis of national survey data was conducted in 1174 healthy adult men and women (ages 21 to 90 years) who provided physiologically plausible dietary data in the 1994-1996 Continuing Survey of Food Intakes by Individuals. Measurements included reported energy intake, protein intake (percentage meeting Recommended Dietary Allowance), micronutrient intakes (percentage meeting Estimated Average Requirements for 14 micronutrients), and BMI., Results: Adults who were 61 years or older consumed a greater total variety of foods, chose foods from a wider range of food groups, had a greater variety of micronutrient-dense foods and energy-weak foods, and had a lower variety of micronutrient-weak foods compared with adults ages 21 to 60 years (p < .05 to.001). However, older adults with low BMIs (< 22 kg/m2) consumed a lower variety of energy-dense foods compared with older adults with higher BMIs (p < .05). The variety of energy-dense foods predicted both energy intake and BMI at all ages in multiple regression models controlling for confounding variables (R2 = .124 for energy, R2 = .574 for BMI, p < .001). A higher percentage of older persons had inadequate micronutrient intakes compared with younger persons (p < .05), especially vitamin E, calcium, and magnesium, but consumption of a particularly wide variety of micronutrient-rich foods helped counterbalance these trends (p < .05). Older adults who had a low BMI and consumed a low variety of micronutrient-dense foods were particularly at nutritional risk, with only 65.4% consuming the Recommended Dietary Allowance for protein and none meeting the Estimated Average Requirements for all 14 micronutrients., Conclusions: In contrast to previous suggestions that older persons consume a monotonous diet, this study showed that adults who were 61 years or older consumed a greater total food variety, and a greater variety of micronutrient-dense and energy-weak foods, compared with adults who were 60 years or younger. Although consumption of a low variety of energy-dense foods may contribute to reduced energy intake and body weight at any age, the variety of micronutrient-dense foods consumed needs to increase in old age to prevent micronutrient deficiencies. These findings suggest that all adults need advice on the changing needs for dietary variety with aging to maintain health, and that older persons with low BMI are particularly vulnerable to dietary shortfalls.

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(2)), we measured glucose in the interstitial space by an automated monitoring procedure (continuous glucose monitoring system, CGMS) for up to 3 consecutive days (mean 706 glucose readings per subject). We examined the association between interstitial glucose (which lags blood glucose by approximately 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.

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 +/- SEM) 48.9 +/- 1.7 kg/m(2)]. TEE was measured over 14 d using the doubly labeled water method, REE and the thermic effect of feeding (TEF) 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(2)) for data analysis. TEE and REE increased with increasing BMI tertile: TEE, 12.80 +/- 0.5, 14.67 +/- 0.5, and 16.10 +/- 0.9 MJ/d (P < 0.01); REE, 7.87 +/- 0.2, 8.78 +/- 0.3, and 9.94 +/- 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 +/- 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.

Background: Little is known about the determinants of individual variability in body weight and fat loss after gastric bypass surgery or about the effects of massive weight loss induced by this surgery on energy requirements., Objectives: The objectives were to determine changes in energy expenditure and body composition with weight loss induced by gastric bypass surgery and to identify presurgery predictors of weight loss., Design: Thirty extremely obese women and men with a mean (+/- SD) age of 39.0 +/- 9.6 y and a body mass index (BMI; in kg/m(2)) of 50.1 +/- 9.3 were tested longitudinally under weight-stable conditions before surgery and after weight loss and stabilization (14 +/- 2 mo). Total energy expenditure (TEE), resting energy expenditure (REE), body composition, and fasting leptin were measured., Results: Subjects lost 53.2 +/- 22.2 kg body weight and had significant decreases in REE (-2.4 +/- 1.0 MJ/d; P < 0.001) and TEE (-3.6 +/- 2.5 MJ/d; P < 0.001). Changes in REE were predicted by changes in fat-free mass and fat mass. The average physical activity level (TEE/REE) was 1.61 at both baseline and follow-up (P = 0.98). Weight loss was predicted by baseline fat mass and BMI but not by any energy expenditure variable or leptin. Measured REE at follow-up was not significantly different from predicted REE., Conclusions: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain.

Background: The relative influence of diet and physical activity on body fatness remains uncertain., Objective: The objective of the study was to investigate associations of dietary variables and physical activity with body fatness in urban Chinese adults., Design: We conducted a cross-sectional study in 130 weight-stable men and women aged 35-49 y. Subjects were selected from upper and lower tertiles of dietary fat and physical activity on the basis of screening questionnaires. Dietary intake was assessed by weighed food intake, physical activity level (PAL) was calculated as the ratio of predicted total energy expenditure (TEE) to predicted resting energy expenditure, and body composition was measured with the use of (2)H(2)O. Reported energy intake and predicted TEE were validated against TEE determined with the use of (2)H(2)(18)O (n = 73)., Results: Body fatness was positively associated with dietary variety (ie, variety of ingredients) (partial r = 0.186, P = 0.039) and frequency of consuming restaurant foods (partial r = 0.237, P = 0.001) and negatively associated with PAL (partial r = -0.307, P = 0.001) in a multiple regression analysis that controlled for sex and confounders. The combined variance accounted for by dietary variety and restaurant food consumption (9.1%) was equivalent to that for PAL (9.4%). Neither dietary fat nor energy density predicted body fatness, but dietary energy density predicted within-subject day-to-day variation in reported energy intake (P < 0.001)., Conclusions: Dietary variety, frequency of restaurant food consumption, and PAL significantly predicted body fatness in urban Chinese adults, but dietary fat did not. These findings support previous studies in US adults and suggest that dietary variables other than fat have an important influence on adult body composition.

Objective: To review existing methods and illustrate the use of a new, simple method for identifying inaccurate reports of dietary energy intake (rEI)., Design: Comparison of rEI with energy requirements estimated by using total energy expenditure predicted (pTEE) from age, weight, height and sex using a previously published equation. Propagation of error calculations was performed and cut-offs for excluding rEI at plus or minus two standard deviations (+/-2 SD) and +/-1 SD for the agreement between rEI and pTEE were established., Setting: Dietary survey in a US national cohort: the Continuing Survey of Food Intakes by Individuals (CSFII), 1994-96., Subjects: Men and non-pregnant, non-lactating women aged 21-45 years in the CSFII who provided two multiple-pass 24-hour recalls, height and weight (n = 3755)., Results: Average rEI was 77% of pTEE in men, and 64% of pTEE in women. Calculated cut-offs were rEI <40% or >160% of pTEE (+/-2 SD) and <70% or >130% of pTEE (+/-1 SD), respectively. Use of only the +/-1 SD cut-offs, not the +/-2 SD cut-offs, resulted in a relationship between rEI and body weight similar to what was expected (based on an independently calculated relationship between rEI and measured TEE). Exclusion of rEI outside either the +/-2 SD (11% of subjects) or +/-1 SD (57% of subjects) cut-offs did not affect mean reported macronutrient intakes, but did markedly affect relationships between dietary composition and body mass index., Conclusions: When examining relationships between diet and health, use of +/-1 SD cut-offs may be preferable to +/-2 SD cut-offs for excluding inaccurate dietary reports.

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.

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.

Emerging research indicates that eating timing may influence dietary intake and metabolic health. However, studies to date have not examined the association of multiple measures of eating timing with both dietary intake and metabolic health in adults with overweight and obesity. To examine the association of multiple measures of eating timing with dietary intake (ie, dietary composition, diet quality, and eating frequency) and metabolic health (ie, body composition and cardiometabolic risk). This is a cross-sectional analysis of baseline data from a weight loss and maintenance intervention collected from May 2015 to January 2018. Participants were women with overweight or obesity who were dependents of active duty and retired military personnel (N = 229; mean ± standard error, BMI = 34.7 ± 0.4 kg/m2, age = 40.9 ± 0.7 years). The study was conducted at military installations in Massachusetts, Connecticut, New York, Colorado, and Kentucky. Eating timing variables examined included daily eating interval (time between first and last eating occasion), time-restricted eating (≤11 hours daily eating interval), early energy eaters (eating ≥60% of energy during the first half of time awake), and bedtime eaters (eating within 2 hours of bedtime). The main analysis was limited to those reporting plausible energy intake (64% of total sample [n = 146]). Linear, quantile, or logistic regression models were used to determine the association of eating timing with measures of dietary intake and metabolic health. In individuals reporting plausible energy intake, each additional 1 hour in daily eating interval was associated with 53 kcal higher energy intake, higher glycemic load, eating frequency, and waist circumference (P < 0.05 for all). Significant associations were observed for: time-restricted eating and a lower energy intake, glycemic load, and eating frequency; early energy eating and higher carbohydrate intake; bedtime eating and a higher energy intake, glycemic load, and eating frequency. These findings lend support for the mechanistic targeting of eating timing in behavioral interventions aimed at improving dietary intake and body composition. [ABSTRACT FROM AUTHOR]

Physiological adaptations to intentional weight loss can facilitate weight regain. This review summarizes emerging findings on hypothalamic and brainstem circuitry in the regulation of body weight and identifies promising areas for research to improve therapeutic interventions for sustainable weight loss. There is good evidence that body weight is actively regulated in a homeostatic fashion similar to other physiological parameters. However, the defended level of body weight is not fixed but rather depends on environmental conditions and genetic background in an allostatic fashion. In an environment with plenty of easily available energy-dense food and low levels of physical activity, prone individuals develop obesity. In a majority of individuals with obesity, body weight is strongly defended through counterregulatory mechanisms, such as hunger and hypometabolism, making weight loss challenging. Among the options for treatment or prevention of obesity, those directly changing the defended body weight would appear to be the most effective ones. There is strong evidence that the mediobasal hypothalamus is a master sensor of the metabolic state and an integrator of effector actions responsible for the defense of adequate body weight. However, other brain areas, such as the brainstem and limbic system, are also increasingly implicated in body weight defense mechanisms and may thus be additional targets for successful therapies. [ABSTRACT FROM AUTHOR]

Background: The energy intake necessary to maintain weight and body composition is called the energy requirement for weight maintenance and can be determined by using the doubly labeled water (DLW) method. Objective: The objective was to determine the energy requirements of nonobese men and women in the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy 2 study. Design: Energy requirements were determined for 217 healthy, weight-stable men and women [aged >21 to <50 y; 70% female, 77% white; body mass index (BMI; in kg/m2) 22 to <28; 52% overweight] over 28 d with 2 consecutive 14-d DLW assessments in addition to serial measures of body weight and fat-free mass and fat mass by dual-energy X-ray absorptiometry. Energy intake and physical activity were also estimated by self-report over ⩾6 consecutive d in each DLW period. Results: Total daily energy expenditure (TDEE) was consistent between the 2 DLW studies (TDEE1: 2422 ± 404 kcal/d; TDEE2: 2465 ± 408 kcal/d; intraclass correlation coefficient = 0.90) with a mean TDEE of 2443 ± 397 kcal/d that was, on average, 20% (580 kcal/d) higher in men than in women (P < 0.0001). The regression equation relating mean TDEE to demographics and weight was as follows: TDEE (kcal/d) = 1279 + 18.3 (weight, kg) + 2.3 (age, y) 2 338 (sex: 1 = female, 0 = male); R2 = 0.57. When body composition was included, TDEE (kcal/d) = 454 + 38.7 (fat-free mass, kg) 2 5.4 (fat mass, kg) + 4.7 (age in y) + 103 (sex: 1 = female, 0 = male); R2 = 0.65. Individuals significantly underreported energy intake (350 kcal/d; 15%), and underreporting by overweight individuals (w400 kcal/d; 16%) was greater (P < 0.001) than that of normal-weight individuals (w270 kcal/d; 12%). Estimates of TDEE from a 7-d physical activity recall and measured resting metabolic rate also suggested that individuals significantly underreported physical activity (w400 kcal/d; 17%; P < 0.0001). Conclusion: These new equations derived over 1 mo during weight stability can be used to estimate the free-living caloric requirements of nonobese adults [ABSTRACT FROM AUTHOR]

Abstract: Energy-restricted low glycemic load diets are being used increasingly for weight loss. However, the long-term effects of such regimens on mood and cognitive performance are not known. We assessed the effects of low glycemic load (LG) and high glycemic load (HG) energy-restricted diets on mood and cognitive performance during 6 months of a randomized controlled trial when all food was provided. Subjects were 42 healthy overweight adults (age 35±5 years; BMI 27.8±1.6 kg/m2) with a mean weight loss of 8.7±5.0% that did not differ significantly by diet randomization. Mood was assessed by using the Profile of Mood States (POMS) questionnaire. Cognitive performance was assessed by using computerized tests of simple reaction time, vigilance, learning, short-term memory and attention, and language-based logical reasoning. Worsening mood outcome over time was observed in the HG diet group compared to the LG for the depression subscale of POMS (p =0.009 after including hunger as a covariate). There was no significant change over time in any cognitive performance values. These findings suggest a negative effect of an HG weight loss diet on sub-clinical depression but, in contrast to a previous suggestion, provide no support for differential effects of LG versus HD diets on cognitive performance. [Copyright &y& Elsevier]

The effect of aging on energy regulation remains controversial. We compared the effects of underfeeding on changes in energy expenditure and respiratory quotient in young normal weight men and women [YNW, age 25.7 +/- 3.2 y(SD), body mass index (BMI) 23.1 +/- 1.6 kg/m(2)], young overweight men and women (YOW, age 26.1 +/- 3.5 y, BMI 27.7 +/- 2.1 kg/m(2)) and older (OLD) men and women (age 68.4 +/- 3.3 y, BMI 27.4 +/- 3.4 kg/m(2)). The thermic effect of feeding (TEF) during weight maintenance, and changes in resting energy expenditure (REE) and respiratory quotient were determined in response to undereating by an average 3.75 MJ/d for 6 wk. In addition, body composition was measured. No significant differences among the groups were observed in TEF, fasting and postprandial respiratory quotient, or the change in fasting respiratory quotient with underfeeding. However, REE adjusted for fat-free mass and fat mass was significantly lower in OLD subjects compared with YNW and YOW subjects (P < 0.05). In addition, the REE response to weight change was significantly attenuated in the OLD subjects (P = 0.023). These data suggest that the responsiveness of energy expenditure to negative energy balance is attenuated in old age, and provide further support for the hypothesis that mechanisms of energy regulation are broadly disregulated in old age. [ABSTRACT FROM AUTHOR]

Previous studies by our group and others have suggested that nutritional stunting may increase the risk of obesity. To investigate mechanisms that could explain a link between stunting and obesity, a 22-mo follow-up study was conducted in two groups of shantytowns school girls (7-11 y old) in São Paulo, Brazil. One group (n = 15) had mild stunting (defined using a cutoff of -1.4 Z-scores of height-for-age) but normal weight-for-height; the control group (n = 15) had normal weight and height. Similar energy intake, dietary macronutrient composition and energy expenditure were observed in the two groups. Both groups showed comparable levels of IGF-1 that were below the normal range. A significant and positive association between baseline IGF-1 and the change in height-for-age during follow-up was found in all subjects combined (P = 0.044). A significant association was found between the baseline percentage of dietary energy supplied by fat and the gain in weight-for-height during follow-up in girls with mild stunting (P = 0.048), but not in the nonstunted control girls (P = 0.245); however, the slopes of these relationships were not significantly different. This study raises the question of whether a diet high in fat may increase the susceptibility to excess body fat gain in children who are mildly stunted. Further studies are need to explore this issue and to examine the possible etiological role of low levels of IGF-1. [ABSTRACT FROM AUTHOR]

The energy costs of depositing fat and protein in the low-birth-weight infant were determined by multiple-regression analysis from published information on metabolizable-energy intake and fat and protein deposition in groups of subjects fed different dietary regimes. The total energy requirement for deposition was 1.17 kJ/kJ deposited for fat (ie, 1 kJ deposited and 0. 17 kJ expended for deposition, and 2.38 kJ/kJ for protein. These values are similar to published determinations for animal species with simple stomachs. The metabolizable-energy requirement for weight gain during infancy was calculated (range, 12.2-25. 1 kJ/g, or 2.9-6.0 kcal/g; ..., 18.7 kJ/g, or 4.5 kcal/g) from the energy costs offat and protein deposition and published information on changes in body composition during the first year of life. [ABSTRACT FROM AUTHOR]

Highlights: [•] This study provides the first data on cravings from a worksite weight loss program. [•] Both, the intensity and frequency of cravings decreased with weight change. [•] Greater reductions in craving-trait were associated with greater weight change. [•] In the presence of hunger, craving-trait show no associations with weight change. [•] ·Hunger control may be more important than craving control for weight loss. [ABSTRACT FROM AUTHOR]