Body Composition, Dietary Intake, and Energy Expenditure in Nonobese, Prepubertal Children of Obese and Nonobese Biological Mothers

Objective To determine differences in dietary intake, resting energy expenditure, activity level, fat-free mass, and percentage body and abdominal fat in nonobese children of obese mothers compared with nonobese children of nonobese mothers.Design Cross-sectional comparison study. Children's food diaries were analyzed to determine average energy and nutrient content. Resting energy expenditure of children was measured by means of indirect calorimetry. Children's activity levels were estimated through questionnaires administered during interviews. Dual-energy x-ray absorptiometry was used to estimate body composition of children.Subjects Mothers of subjects responded to advertisements and were recruited as nonobese (body mass INDEX=20 to 25) or obese (body mass index ≥30). Offspring included in the study were prepubertal and nonobese (10th to 90th percentile of weight for height by gender). Twelve pairs of children could be matched for weight, gender, and age.Statistical analysis performed Wilcoxon signed rank tests were used to determine differences between the 2 groups of children.Results Percentage abdominal fat was greater (median DIFFERENCE=3.15, P=.001) and fat-free mass was lower (median DIFFERENCE=1.19, P=.04) in children of obese mothers compared with children of nonobese mothers. No statistically significant differences between the 2 groups of children were found for dietary intake, resting energy expenditure, activity level, or percentage body fat.Applications/conclusions The significantly higher percentage of abdominal fat and lower fat-free mass in children of obese mothers may contribute to obesity onset. Use of dual-energy x-ray absorptiometry as a screening tool for nonobese, prepubertal children with an obese parent will help to identify those at risk. Education and lifestyle changes can then be implemented to help prevent the onset of obesity. J Am Diet Assoc. 1999;99:58-65.     

Age, sex, ethnicity, body composition, and resting energy expenditure of obese African American and white children and adolescents

BACKGROUND: African Americans may have a lower resting energy expenditure (REE) than do whites, although the data are limited for obese children and adolescents and for boys. Differences in bone density and trunk lean body mass may account for some of these measured differences in REE. OBJECTIVE: We assessed the REE and body composition of obese African American and white children and adolescents. DESIGN: Obese, 5-17-y-old children and adolescents were evaluated (n = 203). Body composition was assessed by dual-energy X-ray absorptiometry. REE was measured by open-circuit calorimetry. African American and white children were compared. The relation between REE and the independent variables (age, sex, ethnic group, fat mass, and fat-free mass or lean tissue mass) was assessed. RESULTS: Of those evaluated, 66% were girls and 34% were African American. Age, sex, pubertal status, and body composition did not differ significantly by ethnic group. All the independent variables were significantly associated with REE. Using lean tissue mass to account for differences in bone density did not significantly alter the results. REE decreased with age and was lower in the girls than in the boys and in the African Americans than in the whites. When trunk fat-free mass was included in the model in place of whole-body fat-free mass, the ethnic difference in REE decreased. CONCLUSIONS: Adjustment for trunk lean tissue mass partially explains the lower REE of obese African American children and adolescents. The lower relative REE of older obese children suggests the importance of early intervention in the prevention of childhood obesity. The lower REE of girls and of African Americans may contribute to the difficulty in weight management in these groups.     

Energy expenditure in preadolescent African American and white boys and girls: the Baton Rouge Children's Study

BACKGROUND: Low energy expenditure has been identified as a potential risk factor for body fat gain. OBJECTIVE: The objective was to determine the relations between race, sex, body fat, and energy expenditure. DESIGN: As part of the Baton Rouge Children's Study, energy expenditure was examined in 131 preadolescent African American and white girls and boys, further stratified as obese or lean. Total daily energy expenditure (TDEE) was measured by the doubly labeled water method. Resting metabolic rate (RMR) and the thermic effect of food were measured by indirect calorimetry. Fat-free mass and fat mass were measured by dual-energy X-ray absorptiometry. To account for differences in body size, energy expenditure variables were adjusted with the use of fat-free mass or fat-free mass and fat mass as covariates. RESULTS: The African American children had lower TDEE and RMR than did the white children. A lower level of energy expended in physical activity by the African American girls and a lower RMR in the African American boys accounted for the racial differences in TDEE. The white boys had a higher RMR than did the white girls. The girls had a lower TDEE and expended less energy in activity than did the boys. Energy expended in activity was lower in the obese children. CONCLUSIONS: The African American children expended less energy than did the white children. The obese children spent less time engaged in activity or engaged in lower-intensity activity. Obese children may maintain their obese state by spending less time in physical activity, but they do not have a reduced RMR or thermic effect of food.     

Body composition and energy expenditure in Duchenne muscular dystrophy

OBJECTIVE: To investigate the relationship between resting energy expenditure (REE) and body composition in Duchenne Muscular Dystrophy (DMD). DESIGN: An observational study. SETTING: University Research Centre. SUBJECTS: Nine Duchenne children (age range 6-12 y), mean relative weight 128%, agreed to undergo the investigation and all of them completed the study; INTERVENTIONS: Assessment of body composition (total body fat and skeletal muscle mass) by magnetic resonance imaging and resting energy expenditure by indirect calorimetry. MAIN OUTCOME MEASURES: Fat mass (FM; kg and percentage weight), fat-free mass (FFM; kg and percentage weight), muscle mass (kg and percentage weight), resting energy expenditure (kJ/kg body weight and kJ/kg fat-free mass). RESULTS:: In Duchenne children fat mass averages 32% and total skeletal muscle mass 20% of body weight. Resting energy expenditure per kg of body weight falls within the normal range for children of the same age range, while when expressed per kg of FFM is significantly higher than reference values. No relationship was found between REE and total skeletal muscle mass. CONCLUSIONS: Our results do not demonstrate a low REE in DMD boys; on the contrary REE per kg of FFM is higher than normal, probably due to the altered FFM composition. We suggest that the development of obesity in DMD children is not primarily due to a low REE but to other causes such as a reduction in physical activity and or overfeeding.     

Body fat distribution and energy metabolism in obese men and women.

Upper body obesity seems to be associated with a better prognosis for weight loss than does lower body obesity. However, the impact of body fat distribution on energy metabolism is not clear.

One hundred fifteen non-diabetic obese Caucasians (64 males and 51 females) and 108 Caucasian lean controls (82 males and 26 females) were studied.

Body composition was assessed by hydrodensitometry and body fat distribution was estimated by the waist-to-thigh circumference ratio (W/T). Values of 24-hour energy expenditure (24h-EE), basal metabolic rate (BMR), sleeping metabolic rate (SMR) and respiratory quotient (RQ) were measured in a respiration chamber.

BMR, adjusted for differences in fat-free mass, fat mass, age and sex, correlated with W/T in obese males (r = 0.40; p < 0.01), but not in obese females. Obese male subjects with upper body obesity had BMR significantly higher than those with lower body obesity (2189 +/? 268 vs 1974 +/? 141 kcal/day; p < 0.01), independently of differences in fat-free mass, fat mass and age. No correlations were found between W/T and adjusted 24h-EE, SMR or RQ in all examined groups.

These findings indicate that in obese males, upper body obesity is associated with increased metabolic rate, possibly related to higher levels of lipid turnover in visceral fat.     

Energy expenditure in African American and white boys and girls in a 2-y follow-up of the Baton Rouge Children's Study

BACKGROUND: Previously reported race and sex differences in energy expenditure (EE) may play a role in body fat gain. OBJECTIVE: The purpose of the study was to determine the relations between race, sex, Tanner stage, and EE. DESIGN: We conducted a 2-y follow-up study of EE in 114 African American (AA) and white girls and boys aged 12.7 +/- 0.1 y ( +/- SE), who were stratified as obese or lean and were part of the Baton Rouge Children's Study. Total daily EE (TDEE) was measured by using doubly labeled water. Resting metabolic rate (RMR) and thermic effect of food were measured by using indirect calorimetry. RESULTS: White children had significantly higher TDEE and RMR than did AA children when fat-free mass was considered. Boys had significantly higher TDEE and RMR than did girls, even after adjustment for differences in size. TDEE and RMR were significantly higher in obese children, as a result of their greater fat-free mass and body fat, than in lean children. Activity-related EE did not differ significantly between obese and lean children. There was a strong relation between initial and 2-y TDEE and RMR. There was a significant decrease in activity-related EE in both racial groups. AA children had significantly more lean limb mass than did white children. CONCLUSIONS: Average TDEE did not change over 2 y, but RMR increased significantly, and activity-related EE decreased significantly. Differences in trunk and limb lean mass of white and AA children may explain some of the ethnic differences in EE. The decrease in physical activity over 2 y may contribute to the risk of obesity.     

Little impact of resting energy expenditure on childhood weight and body composition:: A longitudinal study (EarlyBird 47)

The role of resting energy expenditure (REE) in the development of obesity in children is controversial. Our aim was to test the hypothesis that REE has a meaningful impact on change in weight or body composition in healthy children. Resting energy expenditure by indirect calorimetry and body composition by dual-energy x-ray absorptiometry were measured in 236 children (131 boys) on 7 annual occasions (7-13 years). The effect of REE at 7 years on change in weight and body composition was analyzed using linear mixed effects models. In neither sex was there an interaction between REE at 7 years and change in weight (P > .9). There were weak associations between REE at 7 years and change in body composition in boys but not in girls: for a 418 kJ (100 kcal) lower REE at 7 years, an increase in rate of change in fat mass of approximately 0.1 kg/y and in percentage of fat of 0.2% per year and a decrease in fat-free mass of 0.1 kg/y. Change in REE during follow-up was not significantly associated with body composition changes in either sex (P > .06). Thus, REE has little impact on the wide variation in weight gain at this age; although in boys, some fat was simply exchanged for lean, the effect was small. Resting energy expenditure does not appear to provide an explanation for childhood obesity.     

Association of physical activity with body-composition indexes in children aged 6-8 y at varied risk of obesity

BACKGROUND: Physical inactivity increases the risk of obesity, but the relations between reported levels of physical activity (PA) and measures of body fatness (BF) in children are remarkably inconsistent. OBJECTIVE: We examined the relation between objective measures of PA and body-composition indexes in nonobese children. DESIGN: A cross-sectional study was conducted in 100 children aged 6-8 y who were recruited according to their risk of future obesity: high-risk children had >/=1 obese parent [body mass index (BMI; in kg/m(2)): >30] and low-risk children had 2 nonobese biological parents (BMI: <30). Free-living activity energy expenditure (AEE) and PA level were calculated from 7-d doubly labeled water measurements, time spent in light-intensity activity was assessed by heart rate monitoring, and body composition was determined from isotopic dilution. To adjust for body size, fat mass and fat-free mass were normalized for height and expressed as fat mass index (FMI) and lean mass index (LMI), respectively. RESULTS: High-risk children had significantly higher BMI, LMI, and FMI than did low-risk children, but no group differences in PA were found. AEE and PA level were positively associated with LMI and, after adjustment for sex and fat-free mass, negatively associated with FMI but not with BMI. Boys who spent more than the median time in light-intensity activities had significantly higher FMI than did less sedentary boys. This difference was not observed in girls. CONCLUSIONS: AEE and PA level were negatively associated with BF in nonobese children. Accurate measures of body composition are essential to appropriate assessment of relations between PA and obesity risk.     

Aspirin as a promoter of ephedrine-induced thermogenesis: potential use in the treatment of obesity

Chronic administration of aspirin to obese mice had no effect on energy balance and body composition. In contrast, ephedrine increased energy expenditure by 9% and reduced body weight and body fat by 18% and 50%, respectively: obesity, however, was reduced but not reversed. In the presence of both ephedrine and aspirin, increase in energy expenditure found during treatment with ephedrine alone was doubled, and the obese group lost greater than 75% of body fat: obesity was reversed. These studies indicate that although aspirin administered alone has no influence on energy balance it can markedly potentiate thermogenic properties of ephedrine, effects which led to a normalization of body composition of the obese to that of the lean. Such ephedrine-aspirin mixtures, often found in over-the-counter preparations for asthma and bronchial disorders, could be put to new use as aids for treatment of human obesity.     

Energy intake, not energy output, is a determinant of body size in infants

BACKGROUND: It has been proposed that the primary determinants of body weight at 1 y of age are genetic background, as represented by parental obesity, and low total energy expenditure. OBJECTIVE: The objective was to determine the relative contributions of genetic background and energy intake and expenditure as determinants of body weight at 1 y of age. DESIGN: Forty infants of obese and 38 infants of lean mothers, half boys and half girls, were assessed at 3 mo of age for 10 risk factors for obesity: sex, risk group (obese or nonobese mothers), maternal and paternal body mass index, body weight, feeding mode (breast, bottle, or both), 3-d energy intake, nutritive sucking behavior during a test meal, total energy expenditure, sleeping energy expenditure, and interactions among them. RESULTS: The only difference between risk groups at baseline was that the high-risk group sucked more vigorously during the test meal. Four measures accounted for 62% of the variability in weight at 12 mo: 3-mo weight (41%, P = 0.0001), nutritive sucking behavior (9%, P = 0.0002), 3-d food intake (8%, P = 0.0002), and male sex (3%, P = 0.05). Food intake and sucking behavior at 3 mo accounted for similar amounts of variability in weight-for-length, body fat, fat-free mass, and skinfold thickness at 12 mo. Contrary to expectations, neither total nor sleeping energy expenditure at 3 mo nor maternal obesity contributed to measures of body size at 12 mo. CONCLUSIONS: Energy intake contributes significantly to measures of body weight and composition at 1 y of age; parental obesity and energy expenditure do not.     

Whole-body protein turnover and resting energy expenditure in obese, prepubertal children

BACKGROUND: Obesity is becoming more frequent in children; understanding the extent to which this condition affects not only carbohydrate and lipid metabolism but also protein metabolism is of paramount importance. OBJECTIVE: We evaluated the kinetics of protein metabolism in obese, prepubertal children in the static phase of obesity. DESIGN: In this cross-sectional study, 9 obese children (x +/- SE: 44+/-4 kg, 30.9+/-1.5% body fat) were compared with 8 lean (28+/-2 kg ,16.8+/-1.2% body fat), age-matched (8.5+/-0.2 y) control children. Whole-body nitrogen flux, protein synthesis, and protein breakdown were calculated postprandially over 9 h from 15N abundance in urinary ammonia by using a single oral dose of [15N]glycine; resting energy expenditure (REE) was assessed by indirect calorimetry (canopy) and body composition by multiple skinfold-thickness measurements. RESULTS: Absolute rates of protein synthesis and breakdown were significantly greater in obese children than in control children (x +/- SE: 208+/-24 compared with 137+/-14 g/d, P < 0.05, and 149+/-20 compared with 89+/-13 g/d, P < 0.05, respectively). When these variables were adjusted for fat-free mass by analysis of covariance, however, the differences between groups disappeared. There was a significant relation between protein synthesis and fat-free mass (r = 0.83, P < 0.001) as well as between protein synthesis and REE (r = 0.79, P < 0.005). CONCLUSIONS: Obesity in prepubertal children is associated with an absolute increase in whole-body protein turnover that is consistent with an absolute increase in fat-free mass, both of which contribute to explaining the greater absolute REE in obese children than in control children.     

Effects of familial predisposition to obesity on energy expenditure in multiethnic prepubertal girls

BACKGROUND: The prevalence of childhood obesity is increasing and the causes of this are unknown. OBJECTIVE: The objective of this study was to determine whether energy expenditure (EE), measured by 24-h calorimetry and doubly labeled water, differed in normal-weight-for-height, multiethnic prepubertal girls with or without a familial predisposition to obesity. DESIGN: Normal-weight, prepubertal white (n = 52), African American (n = 30), and Hispanic (n = 19) girls with a mean (+/-SD) age of 8.5 +/- 0.4 y were studied according to parental leanness and overweight or obesity. The girls were grouped according to whether they had 2 lean parents (n = 30), 2 obese parents (n = 27), or 1 lean and 1 obese parent (n = 44). Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24-h EE, respiratory quotient, heart rate, and activity were measured by 24-h room calorimetry; free-living total EE (TEE), activity-related EE (AEE), and physical activity level were measured by doubly labeled water. EE was standardized by fat-free mass (FFM). RESULTS: There were no significant differences among familial groups in weight, height, fat mass, FFM, or percentage body fat. African American girls had a higher FFM than did white or Hispanic girls (P < 0.05). BMR, SMR, 24-h EE, respiratory quotient, heart rate, and activity levels were not significantly different among familial groups. Additionally, there were no significant familial group differences in TEE, AEE, or physical activity level. However, BMR, SMR, and TEE were lower in African American girls than in white girls (P < 0.05). CONCLUSION: There was no significant difference in EE between normal-weight, multiethnic prepubertal girls predisposed to obesity and those not predisposed to obesity.     

Relationship between birth weight and body composition, energy metabolism, and sympathetic nervous system activity later in life

OBJECTIVE: Epidemiological studies suggest that high birth weight might be associated with an increased risk of obesity later in life. Programming of metabolic, endocrine, and/or autonomic pathways during intrauterine development has been proposed to explain this association. RESEARCH METHODS AND PROCEDURES: To determine the relationship between birth weight and body composition and energy metabolism later in life, we measured fat mass and fat-free mass (hydrodensitometry or double-energy X-ray absorptiometry), 24-hour energy expenditure, sleeping metabolic rate, and 24-hour respiratory quotient (respiratory chamber) in 272 adult nondiabetic Pima Indians (161 males/ 111 females, age 25 +/- 5 years, mean +/- SD). In these subjects, birth weight varied over a wide range (2,000 to 5,000 g). Individuals known to be offspring of diabetic pregnancies were excluded. In 44 of the 272 subjects, muscle sympathetic nerve activity was assessed by microneurography. RESULTS: Birth weight was positively correlated with adult height (r = 0.20, p < 0.001) and fat-free mass (r = 0.21, p < 0.001), but not with fat mass (r = 0.01, not significant). Sleeping metabolic rate, adjusted for age, sex, fat-free mass, and fat mass, was negatively related to birth weight (r = -0.13, p < 0.05), whereas adjusted 24-hour energy expenditure (r = 0.07, not significant) and 24-hour respiratory quotient (r = -0.09, not significant) were not. There was no relationship between birth weight and muscle sympathetic nerve activity (r = 0.12, not significant, n = 44). DISCUSSION: In Pima Indians who are not offspring of diabetic pregnancies, high birth weight is associated with increased height and lean body mass, but not with increased adiposity later in life. Although high birth weight may be associated with relatively low resting energy expenditure, it is not associated with major abnormalities in 24-hour energy metabolism or with low muscle sympathetic nerve activity later in life.     

Leptin levels are associated with fat oxidation and dietary-induced weight loss in obesity

OBJECTIVE: To examine the relationship between fasting plasma leptin and 24-hour energy expenditure (EE), substrate oxidation, and spontaneous physical activity (SPA) in obese subjects before and after a major weight reduction compared with normal weight controls. To test fasting plasma leptin, substrate oxidations, and SPA as predictive markers of success during a standardized weight loss intervention. RESEARCH METHODS AND PROCEDURES: Twenty-one nondiabetic obese (body mass index: 33.9 to 43.8 kg/m(2)) and 13 lean (body mass index: 20.4 to 24.7 kg/m(2)) men matched for age and height were included in the study. All obese subjects were reexamined after a mean weight loss of 19.2 kg (95% confidence interval: 15.1-23.4 kg) achieved by 16 weeks of dietary intervention followed by 8 weeks of weight stability. Twenty-four-hour EE and substrate oxidations were measured by whole-body indirect calorimetry. SPA was assessed by microwave radar. RESULTS: In lean subjects, leptin adjusted for fat mass (FM) was correlated to 24-hour EE before (r = -0.56, p < 0.05) but not after adjustment for fat free mass. In obese subjects, leptin correlated inversely with 24-hour and resting nonprotein respiratory quotient (r = -0.47, p < 0.05 and r = -0.50, p < 0.05) both before and after adjustments for energy balance. Baseline plasma leptin concentration, adjusted for differences in FM, was inversely related to the size of weight loss after 8 weeks (r = -0.41, p = 0.07), 16 weeks (r = -0.51, p < 0.05), and 24 weeks (r = -0.50, p < 0.05). DISCUSSION: The present study suggests that leptin may have a stimulating effect on fat oxidation in obese subjects. A low leptin level for a given FM was associated with a greater weight loss, suggesting that obese subjects with greater leptin sensitivities are more successful in reducing weight.     

Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females

We assessed the effect of ingestion of green tea (GT) extract along with a low-energy diet (LED) on resting energy expenditure (REE), substrate oxidation and body weight as GT has been shown to increase energy expenditure and fat oxidation in the short term in both animals and people. Forty-six overweight women (BMI 27.6 (sd 1.8) kg/m2) were fed in energy balance from day 1 to day 3, followed by a LED with GT (1125 mg tea catechins +225 mg caffeine/d) or placebo (PLAC) from day 4 to day 87. Caffeine intake was standardised to 300 mg/d. Energy expenditure was measured on days 4 and 32. Reductions in weight (4.19 (sd 2.0) kg PLAC, 4.21 (sd 2.7) kg GT), BMI, waist:hip ratio, fat mass and fat-free mass were not statistically different between treatments. REE as a function of fat-free mass and fat mass was significantly reduced over 32 d in the PLAC group (P<0.05) but not in the GT group. Dietary restraint increased over time (P<0.001) in both groups, whereas disinhibition and general hunger decreased (P<0.05). The GT group became more hungry over time and less thirsty, and showed increased prospective food consumption compared with PLAC (P<0.05). Taken together, the ingestion of GT along with a LED had no additional benefit for any measures of body weight or body composition. Although the decrease in REE as a function of fat-free mass and fat mass was not significant with GT treatment, whereas it was with PLAC treatment, no significant effect of treatment over time was seen, suggesting that a robust limitation of REE reduction during a LED was not achieved by GT.     

Obesity: determinants and therapeutic initiatives.

There are several possible determinants of obesity, including impaired thermogenesis and the differential utilization of fuels in different tissues. Whereas hypometabolism may initiate obesity in some people, once obese, individuals tend to manifest a higher resting metabolic rate because of their greater fat-free mass, exhibit an impaired thermic response to food, and expend more calories than lean individuals for equivalent amounts of activity. As a result, over a 24-h period, obese people generally expend more energy than lean people. A second determinant of obesity is related to fuel utilization and suggests that those predisposed to be obese may have an innate insulin resistance in muscle, leading to decreased uptake, oxidation, and storage of glucose in this tissue. As a result, the glucose is shunted to adipose tissue, where it is stored. With regard to treatment of obesity, emphasis on increased energy expenditure through the inclusion of reasonable amounts of activity is essential. However, this must always be combined with restraint in caloric intake.     

Effect of time interval between food intake and exercise on substrate oxidation during exercise in obese and lean children

Background & aims

Exercise induces adaptations in fat metabolism favourable to the treatment of obesity. However, time interval between meal and exercise alters substrate bioavailability and oxidation during exercise. The aim of this study was therefore to investigate the effect of time interval between food intake and exercise on substrate oxidation rates in obese and lean children.

Methods

The metabolic responses to exercise of nine obese children (10.3 ± 1.8 years; %body fat: 36.1 ± 6.1) and seven lean children (9.2 ± 1.6 years; %body fat: 22.2 ± 4.1) were compared 1 h (time interval 1, TI1) and 3 h (TI3) after a standardized breakfast.

Results

Despite significantly lower plasma glucose and insulin concentrations and large effect size suggesting a higher plasma FFA availability (lean, 1.43, obese 0.98), fat oxidation was not significantly increased in TI3 compared to TI1 in both lean and obese children. Fat oxidation contributed marginally to energy expenditure during exercise (<20%) in both conditions and groups but was moderately increased during TI3 compared to TI1 in lean children (effect size: 0.54).

Conclusions

The low contribution of fat oxidation to energy expenditure during exercise in obese and lean children fed 3 h before exercise questions the efficacy of moderate intensity exercise to favourably affect fat balance.     

Prediction of resting energy expenditure in a large population of obese children

BACKGROUND: Recommendations for energy intake in obese children rely on accurate methods for measuring energy expenditure that cannot be assessed systematically. OBJECTIVE: The aim was to establish and validate new equations for predicting resting energy expenditure (REE), specifically in obese children. DESIGN: REE (indirect calorimetry) and body composition (bioelectrical impedance analysis) were measured in 752 obese subjects aged 3-18 y. The first cohort (n=471) was used to establish predictive equations, the second (and independent) cohort (n=211) was used to validate these equations, and the third cohort, a follow-up group of children who lost weight (n=70), was used to examine predictive REE in the postobese period. REE values predicted with the use of various published equations and the new established equation were compared with measured REE by using the Bland-Altman method and Student's t tests. RESULTS: In cohort 1, significant determinants of the new prediction equations were fat-free mass in boys (model R2=0.79) and age and fat-free mass in girls (model R2=0.76). External validation conducted by using the Bland-Altman method and Student's t tests, in cohort 2, showed no significant difference between measured REE and predicted REE with the new equation. When already published equations were applied, systematical bias appeared with all published equations except for that of the World Health Organization. In cohort 3, the children who lost weight, almost all equations significantly underestimated REE. CONCLUSIONS: These new predictive equations allow clinicians to estimate REE in an obese pediatric population with sufficient and acceptable accuracy. This estimation may be a strong basis for energy recommendations in childhood obesity.     

A reappraisal of the caloric requirements of men

The resting metabolic rates (RMR) of 60 lean and obese men, aged 18-82 y and weighing 60-171 kg, were measured and body compositions were determined. Body compositional variables reflecting active protoplasmic tissue were all highly interrelated. Body weight alone gave prediction values for RMR that were comparable to those of other variables of active protoplasmic tissue mass. Regional distribution of fat had no influence on the RMR and the influence of age on RMR was trivial. The classic prediction equations and tables overestimate RMR of men. The 95%-confidence limits for both lean and obese men were broad. This conclusively demonstrates that metabolic efficiency is not necessarily or exclusively related to obesity. New regression equations for predicting the RMR based on weight and fat-free mass were developed: RMR = 879 + 10.2 WT kg and RMR = 290 + 22.3 FFMD kg, where FFMD is fat-free mass from densitometry measurements.