A longitudinal study of resting energy expenditure relative to body composition during puberty in African American and white children

Childhood Obesity: An Updated Review

BACKGROUND

Childhood obesity is an important and serious public health problem worldwide.

OBJECTIVE

This article aims to familiarize physicians with the evaluation, management, and prevention of childhood.

METHODS

A PubMed search was conducted in May, 2021, in Clinical Queries using the key terms "obesity" OR "obese". The search included clinical trials, randomized controlled trials, case-control studies, cohort studies, meta-analyses, observational studies, clinical guidelines, case reports, case series, and reviews. The search was restricted to English literature and children. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Most obese children have exogenous obesity characterized by a growth rate for height above the 50th percentile, normal intelligence, normal genitalia, and lack of historical or physical evidence of an endocrine abnormality or a congenital syndrome. Obese children are at risk for dyslipidemia, hypertension, diabetes mellitus, non-alcoholic fatty liver disease, obstructive sleep apnea, psychosocial disturbances, impaired quality of life, and shorter life expectancy. The multitude of serious comorbidities necessitates effective treatment modalities. Dietary modification, therapeutic exercise, and behavioral modification are the fundamentals of treatment. Pharmacotherapy and/or bariatric surgery should be considered for obese individuals who do not respond to the above measures and suffer from a serious comorbid condition.

CONCLUSION

Childhood obesity, once established, is often refractory to treatment. Most treatment programs lead to a brief period of weight loss, followed by rapid re-accumulation of the lost weight after the termination of therapy. As such, preventive activity is the key to solving the problem of childhood obesity. Childhood obesity can be prevented by promoting a healthy diet, regular physical activity, and lifestyle modification. Parents should be encouraged to get involved in school and community programs that improve their children's nutritional status and physical activity.

Sex and timing of gonadectomy relative to puberty interact to influence weight, body composition, and feeding behaviors in mice

Gonadal sex steroids are important regulators of energy balance in adult rodents, and gonadectomy (GDX) has opposing effects on weight gain in sexually mature males and females. Puberty is associated with the emergence of sex differences in weight, body composition, and feeding behaviors, yet the role of gonadal hormones at puberty remains unclear. To address this, we performed GDX or sham surgery in male and female C57Bl/6 mice at postnatal day (P)25 (prepubertal) or P60 (postpubertal) timepoints and measured weight and body composition for 35 days, after which ad libitum and operant food intake was measured using Feeding Experimentation Device 3 (FED3s) in the home cage. Consistent with previous studies, postpubertal GDX caused weight gain in females and weight loss in males and increased adiposity in both sexes. However, prepubertal GDX decreased weight gain and altered body composition across the adolescent transition (P25 to P60) in males but had no effect in females. Despite the varied effects on weight, GDX decreased food intake and motivation for food as assessed in operant tasks regardless of sex or timing of surgery relative to puberty. Our findings indicate that GDX interacts with both sex and age at surgery to influence weight, body composition, and feeding behavior.

Longitudinal analysis of resting energy expenditure and body mass composition in physically active children and adolescents

Background

Monitoring body composition and changes in energy expenditure during maturation and growth is significant, as many components can influence body structure in adulthood. In the case of young players, when these changes can influence their strength and power, it seems to be equally important. Our aim was to examine whether resting energy expenditure (REE) and body composition would change after 10 months from baseline in physically active children and adolescents.

Methods

We obtained data from 80 children and adolescents aged 9 to 17 years at two measurement points: the baseline in September 2018 and after 10 months in July 2019. The study was carried out using a calorimeter (Fitmate MED, Cosmed, Rome, Italy), a device used to assess body composition using by the electrical bioimpedance method by means of a segment analyzer (TANITA MC-980). The Student’s t-test and linear regression analysis were used. Using the stepwise forward regression procedure, the selection of factors in a statistically significant way that describes the level of REE was made.

Results

We noticed that REE was not significantly different between baseline (1596.94 ± 273.01 kcal) and after 10 months (1625.38 ± 253.26 kcal). When analyzing the difference in REE between studies girls, we found body height as a significant predictor. The results of our study show a negative relationship between growth and REE. Differences between sexes and age in REE between baseline and after 10 months were not significant.

Conclusions

Our study involving physically active children and adolescents, which used repeated objective measures and longitudinal statistical modeling to analyze them, was unable to demonstrate any interaction between body weight change, body composition measurements, and REE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03326-x.

The Diagnostic-Measurement Method-Resting Energy Expenditure Assessment of Polish Children Practicing Football

Establishing the amount of energy needed to cover the energy demand of children doing sport training and thus ensuring they achieve an even energy balance requires the resting energy expenditure (REE) to be estimated. One of the methods that measures REE is the indirect calorimetry method, which may be influenced by many factors, including body composition, gender, age, height or blood pressure. The aim of the study was to assess the correlation between the resting energy expenditure of children regularly playing football and selected factors that influence the REE in this group. The study was conducted among 219 children aged 9 to 17 using a calorimeter, a device used to assess body composition by the electrical bioimpedance method by means of segment analyzer and a blood pressure monitor. The results of REE obtained by indirect calorimetry were compared with the results calculated using the ready-to-use formula, the Harris Benedict formula. The results showed a significant correlation of girls’ resting energy expenditure with muscle mass and body height, while boys’ resting energy expenditure was correlated with muscle mass and body water content. The value of the REE was significantly higher (p ≤ 0.001) than the value of the basal metabolic rate calculated by means of Harris Benedict formula. The obtained results can be a worthwhile suggestion for specialists dealing with energy demand planning in children, especially among those who are physically active to achieve optimal sporting successes ensuring proper functioning of their body.

Approach to the Patient: Management of the Post-Bariatric Surgery Patient With Weight Regain

CONTEXT

Weight regain (WR) after bariatric surgery is emerging as a common clinical problem due to the increase in the number of procedures performed. Early interventions are necessary to curtail the potential recurrence of comorbid conditions. However, it is often difficult to recognize WR early enough to introduce mitigating measures because there are no current guidelines for timely diagnosis and assessment of the severity of this condition.

OBJECTIVE

We present a practical approach for the early recognition of WR, based on 11-year follow-up data from our multiethnic bariatric surgery patient population.

METHODS

We classify WR according to the rate of increase in weight relative to nadir weight, normalized per 30-day interval. We also review pertinent literature about the etiologic factors contributing to WR after bariatric surgery.

RESULTS

According to our algorithm, mild, moderate, and rapid WR are defined as weight increases of 0.2% to <0.5%, 0.5% to 1.0%, and more than 1.0% of nadir weight per 30 days, respectively. Treatment options, including dietary counseling, use of antiobesity medication, and consideration of surgical revision, are described. A case is presented to illustrate the utility of timely identification of WR and the importance of collaboration between bariatric surgeons, obesity medicine specialists, and dietitians.

CONCLUSION

Our approach emphasizes the importance of regular long-term follow-up for all bariatric surgery patients.

Weight Recidivism After Roux-en-Y Gastric Bypass Surgery: An 11-Year Experience in a Multiethnic Medical Center

OBJECTIVE

Weight recidivism following Roux-en-Y gastric bypass (RYGB) is common and is associated with recurrence of comorbidities. Studies with long-term follow-up of recidivism quantified by weight regain (WR) are lacking. A retrospective review of all RYGB at our center from 2004 to 2015 was performed to examine the effects of race and type 2 diabetes on WR following RYGB.

METHODS

Multivariable linear mixed models were used for the effects of time and race on weight, WR relative to nadir weight (WR/nadir), and WR relative to maximal weight loss, and Cox regressions were used for low, moderate, and high WR/nadir.

RESULTS

A total of 1,395 participants were identified. The sample was limited to African American (AA), Caucasian American (CA), and Hispanic American (HA) participants. The effects of time (P < 0.0001), race (P < 0.0001), and race × time interaction (P = 0.0008) on weight trajectory were significant. AA had significantly more WR than CA (P < 0.01). AA and HA had a higher hazard ratio for having low, moderate, and rapid WR/nadir.

CONCLUSIONS

Racial disparities after RYGB include WR and particularly affect AA. Understanding the etiologic factors that contribute to these disparities is important to optimize the long-term clinical outcomes of bariatric surgery.

Ghrelin and Peptide YY Change During Puberty: Relationships With Adolescent Growth, Development, and Obesity

CONTEXT

Pubertal adolescents show strong appetites. How this is mediated is unclear, but ghrelin and peptide YY (PYY) play potentially important roles.

OBJECTIVE

To measure ghrelin and PYY change in relation to pubertal growth.

DESIGN

Three-year prospective cohort study.

SETTING

Australian regional community.

PARTICIPANTS

Eighty healthy adolescents (26 girls; 54 boys) recruited at 10 to 13 years.

MAIN OUTCOME MEASURES

Fasting circulating total ghrelin, total PYY, IGF-1, insulin, leptin (via radioimmunoassay), estradiol and testosterone (via mass spectrometry), anthropometry, and body composition (via bioelectrical impedance).

RESULTS

Adolescents exhibited normal developmental change. Mixed models revealed positive associations for ghrelin to age2 (both sexes: P < 0.05), indicating a U-shaped trend over time. Ghrelin was also inversely associated with IGF-1 (both sexes: P < 0.05), leptin in girls (P < 0.01), and insulin in boys (P < 0.05) and negatively correlated with annual height and weight velocity (both sexes: P ≤ 0.01). PYY showed no age-related change in either sex. Neither ghrelin nor PYY were associated with Tanner stage. Weight subgroup analyses showed significant ghrelin associations with age2 in healthy-weight but not overweight and obese adolescents (7 girls; 18 boys).

CONCLUSIONS

Adolescents showed a U-shaped change in ghrelin corresponding to physical and biochemical markers of growth, and no change in PYY. The overweight and obesity subgroup exhibited an apparent loss of the U-shaped ghrelin trend, but this finding may be attributed to greater maturity and its clinical significance is unclear. Further research on weight-related ghrelin and PYY trends at puberty is needed to understand how these peptides influence growth and long-term metabolic risk.

Evaluating the contribution of differences in lean mass compartments for resting energy expenditure in African American and Caucasian American children

BACKGROUND

Resting energy expenditure (REE), adjusted for total lean mass (LM), is lower in African American (AA) than Caucasian American (CA) children. Some adult studies suggest that AA-CA differences in lean mass compartments explain this REE difference. Similar data are limited in children.

OBJECTIVE

To evaluate differences in compartment-specific lean mass between AA and CA children and examine the individual contributions of high-metabolic rate-at-rest trunk lean mass (TrLM) and low-metabolic-rate-at-rest appendicular lean mass (AppLM) for AA-CA differences in REE.

METHODS

We studied a convenience sample of 594 AA (n = 281) and CA (n = 313) children. REE was measured by using indirect calorimetry; dual-energy X-ray absorptiometry was used to assess body composition. ANCOVAs were performed to examine AA-CA differences in TrLM, AppLM and REE. After accounting for age, sex, height, pubertal development, bone mass and adiposity, REE was evaluated adjusting for total LM (model A) and separately adjusting for TrLM and AppLM (model B).

RESULTS

African American children had greater adjusted AppLM (17.8 ± 0.2 [SE] vs. 16.0 ± 0.2 kg, p < 0.001) and lower TrLM (17.2 ± 0.2 vs. 17.7 ± 0.2 kg, p = 0.022) than CA children. REE adjusted for total LM was 77 ± 16 kcal/d lower in AA than CA (p < 0.001). However, after accounting separately for AppLM and TrLM, the discrepancy in REE between the groups declined to 28 ± 19 kcal/d (p = 0.14). In the adjusted model, both TrLM (p < 0.001) and AppLM (p < 0.027) were independently associated with REE.

CONCLUSION

In children, AA-CA differences in REE appear mostly attributable to differences in body composition. Lower REE in AA children is likely due to lower TrLM and greater AppLM.

Associations of Mitochondrial Fatty Acid Oxidation with Body Fat in Premenopausal Women

Higher in vivo fatty acid (FA) oxidation rates have been reported in obese individuals compared to lean counterparts; however whether this reflects a shift in substrate-specific oxidative capacity at the level of the skeletal muscle mitochondria has not been examined. The purpose of this study was to test the hypothesis that in situ measures of skeletal muscle mitochondria FA oxidation would be positively associated with total body fat. Participants were 38 premenopausal women (BMI = 26.5 ± 4.3 kg/m²). Total and regional fat were assessed by dual-energy X-ray absorptiometry (DXA). Mitochondrial FA oxidation was assessed in permeabilized myofibers using high-resolution respirometry and a palmitoyl carnitine substrate. We found positive associations of total fat mass with State 3 (ADP-stimulated respiration) (r = 0.379, p < 0.05) and the respiratory control ratio (RCR, measure of mitochondrial coupling) (r = 0.348, p < 0.05). When participants were dichotomized by high or low body fat percent, participants with high total body fat displayed a higher RCR compared to those with low body fat (p < 0.05). There were no associations between any measure of regional fat and mitochondrial FA oxidation independent of total fat mass. In conclusion, greater FA oxidation in obesity may reflect molecular processes that enhance FA oxidation capacity at the mitochondrial level.

Energy expenditure and intake during puberty in healthy nonobese adolescents: a systematic review

BACKGROUND

Puberty is a time of rapid growth and changing energy requirements and is a risk period for obesity. There is little high-quality evidence on the pubertal alterations of energy expenditure and intake, and this has limited our understanding of energy balance during this important life stage.

OBJECTIVE

The purpose of this study was to summarize existing evidence on pubertal energy expenditure and intake in healthy nonobese adolescents.

DESIGN

Studies were identified through CINAHL, the Cochrane Library, Embase, MEDLINE, and Web of Science databases up to August 2015. Articles presenting objectively measured data for basal or resting metabolic rate (BMR/RMR), total daily energy expenditure (TDEE), and/or energy intake (EI) for ≥2 categories of puberty were included. Relevant data adjusted for fat-free mass (FFM) also were extracted. Data were dichotomized into prepubertal and pubertal groups and compared through the use of standardized mean differences (SMDs). Heterogeneous study methodologies precluded meta-analysis.

RESULTS

The search netted 6770 articles, with 12 included for review. From these, 6 of 9 studies supported significantly higher absolute BMR/RMR during puberty (SMD: 1.10-5.93), and all of the studies favored significantly higher absolute TDEE during puberty (SMD: 0.46-9.55). These corresponded to a 12% difference and an 18% difference in absolute BMR/RMR and TDEE, respectively. Results adjusted for FFM were equivocal, with 3 studies favoring higher (1 significantly) and 3 favoring significantly lower adjusted BMR/RMR during puberty. Only 1 study reported EI, showing 41% and 25% greater absolute intakes in pubertal males and females, respectively. These differences were not significant after adjustment for FFM.

CONCLUSIONS

Reasonably consistent evidence exists to support higher absolute BMR/RMR and TDEE in pubertal than in prepubertal adolescents. Differences are largely accounted for by FFM, among other potential factors such as growth- and puberty-related hormones. This review argues for further research into hormonal influences on pubertal energy balance and subsequent effects on obesity risk.

Physiology of Food Intake Control in Children

The purpose of this review is to draw attention to the limited information available on food intake (FI) control in children and adolescents 7-17 y of age, which is essential for developing food policies and guidelines in this population. Although environmental factors have been the overwhelming focus of research on the causative factors of obesity, research focusing on the physiologic control of appetite in children and adolescents is a neglected area of research. To present this message, a review of FI regulation and the role of food and food components in signaling processes are followed by an examination of the role of hormones during puberty in intake regulation. To examine the interaction of environment and physiology on FI regulation, the effects of exercise, television programs, and food advertisements are discussed. In conclusion, although limited, this literature review supports a need for children and adolescents to be a greater focus of research that would lead to sound nutrition policies and actions to reduce chronic disease. A focus on the environment must be balanced with an understanding of physiologic and behavioral changes associated with this age group.

Smaller size of high metabolic rate organs explains lower resting energy expenditure in Asian-Indian Than Chinese men

BACKGROUND

In Singapore, the obesity prevalence is disproportionately higher in the Asian-Indians and Malays than the Chinese. Lower resting energy expenditure (REE) may be a contributory factor.

OBJECTIVE

We explored the association between ethnicity and REE in Chinese, Asian-Indian and Malay men living in Singapore and determined the influence of body composition, mass/volume of high metabolic rate organs, represented by brain volume and trunk fat-free mass (FFM), and physical activity on ethnic differences.

DESIGN

Two hundred and forty-four men from Singapore (n=100 Chinese, 70 Asian-Indians and 74 Malays), aged 21-40 years and body mass index of 18.5-30.0 kg m(-2), were recruited in this cross-sectional study. REE was assessed by indirect calorimetry and body composition by dual-energy X-ray absorptiometry. Brain volume was measured by magnetic resonance imaging. Physical activity was assessed by the Singapore Prospective Study Program Physical Activity Questionnaire.

RESULTS

REE was significantly lower in Asian-Indians compared with that in Chinese after adjusting for body weight. FFM (total, trunk and limb) and total fat mass were important predictors of REE across all ethnic groups. Brain volume was positively associated with REE only in Malays. Moderate and vigorous physical activity was positively associated with REE only in Asian-Indians and Malays. The difference in REE between Asian-Indians and Chinese was attenuated but remained statistically significant after adjustment for total FFM (59±20 kcal per day), fat mass (67±20 kcal per day) and brain volume (54±22 kcal per day). The association between REE and ethnicity was no longer statistically significant after total FFM was replaced by trunk FFM (which includes heart, liver, kidney and spleen) but not when it was replaced by limb FFM (skeletal muscle).

CONCLUSIONS

We have demonstrated a lower REE in Asian-Indians compared with Chinese who may contribute to the higher rates of obesity in the former. This difference could be accounted for by differences in metabolically active organs.

Insulin resistance is not associated with thermogenic effect of a high-fat meal in obese children

In adults, insulin resistance may decrease the thermogenic effect of food, contributing to weight gain. We aimed to determine the effect of insulin resistance on energy expenditure in children with long-standing obesity. We hypothesized that thermogenic effect of food would decrease with increasing insulin resistance. Energy expenditure was measured using whole room indirect calorimetry in obese children 7 to 18 years old. Participants were fed a high-fat meal with energy content equal to 35% of measured resting energy expenditure. Thermogenic effect of food was measured for 180 minutes posttest meal and expressed as a percent of calories consumed. Body composition was assessed using whole-body dual-energy x-ray absorptiometry. Fasting glucose, insulin, and hemoglobin A1C were measured. Complete data were available for 25 children (median age, 12.1 years; 52% male). As expected, a significant decrease in resting energy expenditure was observed with increasing Tanner stage (P = .02 by Kruskal-Wallis test). Insulin sensitivity, as determined by homeostasis model assessment index equation, did not significantly affect resting energy expenditure (P = .3) or thermogenic effect of food (P = .7) after adjustment for Tanner stage. In conclusion, our study did not find an association between insulin resistance and energy expenditure in obese children.

Resting energy expenditure (REE) in six- to seventeen-year-old Japanese children and adolescents

Accurate estimation of resting energy expenditure (REE) in children and adolescents is important to establish estimated energy requirements for the Japanese population. Our objectives were 1) to determine the REE of 6- to 17-y-old Japanese children and adolescents by indirect calorimetry in order to estimate energy expenditure for this group, 2) to compare measured REE with predicted REE to determine the accuracy of predictive equations of REE for Japanese children and adolescents, and 3) to derive new predictive equations for REE for Japanese children and adolescents based on measured REE. REE was measured in 221 Japanese children and adolescents, aged 6 to 17 y old (113 boys and 108 girls) using a ventilated indirect calorimeter. Anthropometric and body composition measurements were also performed. REE expressed as absolute values increased with age in both genders, and there was a significant difference between genders in the 12-17 y age group. REE was strongly correlated with body weight (BW) and fat-free mass (FFM). REE adjusted for BW or FFM decreased with age in both genders, and a gender difference was still observed in the 12-17 y age group after this adjustment. The highest accuracy of prediction was achieved using the Dietary Reference Intake for Japanese (1969) for boys and the Molnar equation for girls. Step-down multiple regression analysis was carried out using either a combination of age, gender, BW, and height, or a combination of age, gender, FFM, and fat mass (FM). The predictive equation accounted for 75% (R2) and 76% of the variance, respectively. In conclusion, absolute REE increased and REE adjusted for BW or FFM decreased with age. The major determinant of REE was FFM, but significant gender differences were observed in the 12-17 y range for both absolute REE and adjusted REE.

Binge eating in obese adolescents: an evolutionary concept analysis

PURPOSE

The purpose of this paper is to provide an analysis of the concept of binge eating in obese adolescents.

METHODS

Rodgers' evolutionary approach was used to frame this analysis. A search was conducted within the Cumulative Index to Nursing and Allied Health Literature, Medline, and PsycINFO for publications between 1980 and 2011.

FINDINGS

Conceptual shifts in the meaning of binge eating have occurred over the past 30 years, yet the two enduring attributes are consumption of a large amount of food and a loss of control over eating.

CONCLUSION

Though this analysis demonstrates a consensus concerning the core attributes of binge eating, further refinement of the nuances, subtleties, and use of the concept in relation to adolescents is needed.

AFestschriftfor Roland L. Weinsier: Nutrition Scientist, Educator, and Clinician1

Roland L. Weinsier, M.D., Dr.P.H., devoted himself to the fields of nutrition and obesity for more than 35 years. He contributed outstanding work related to the treatment of obesity through dietary and lifestyle change; metabolic/energetic influences on obesity, weight loss, and weight regain; body composition changes accompanying weight loss and regain; the health benefits and risks of weight loss; nutrition education for physicians; and nutrition support of sick patients. He served on the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) National Task Force on Prevention and Treatment of Obesity, as Chair of the University of Alabama at Birmingham's Department of Nutrition Sciences, and as Founder and Director of its NIDDK-funded Clinical Nutrition Research Center. He was a long-time and active member of NAASO, serving in the roles of Councilor, Publications Committee Chair, Continuing Medical Education Course Director, Public Relations Committee Chair, and Membership Committee Co-Chair, to name just a few. He was well respected as a staunch defender of NAASO's scientific integrity in these roles. Sadly, Roland Weinsier died on November 27, 2002. He will be missed and remembered by many as a revered and beloved teacher, mentor, healer, and scholar.

Ethnic differences in the accumulation of fat and lean mass in late gestation

OBJECTIVES

Lower birth weight within the normal range predicts adult chronic diseases, but the same birth weight in different ethnic groups may reflect different patterns of tissue development. Neonatal body composition was investigated among non-Hispanic Caucasians and African Americans, taking advantage of variability in gestational duration to understand growth during late gestation.

METHODS

Air displacement plethysmography assessed fat and lean body mass among 220 non-Hispanic Caucasian and 93 non-Hispanic African American neonates. The two ethnic groups were compared using linear regression.

RESULTS

At 36 weeks of gestation, the average lean mass of Caucasian neonates was 2,515 g vs. that of 2,319 g of African American neonates (difference, P = 0.02). The corresponding figures for fat mass were 231 and 278 g, respectively (difference, P = 0.24). At 41 weeks, the Caucasians were 319 g heavier in lean body mass (P < 0.001) but were also 123 g heavier in fat mass (P = 0.001). The slopes for lean mass vs. gestational week were similar, but the slope of fat mass was 5.8 times greater (P = 0.009) for Caucasian (41.0 g/week) than for African American neonates (7.0 g/week).

CONCLUSIONS

By 36 weeks of gestation, the African American fetus developed similar fat mass and less lean mass compared with the Caucasian fetus. Thereafter, changes in lean mass among the African American fetus with increasing gestational age at birth were similar to the Caucasian fetus, but fat accumulated more slowly. We hypothesize that different ethnic fetal growth strategies involving body composition may contribute to ethnic health disparities in later life.

Puberty and observed energy intake: boy, can they eat!

BACKGROUND

Anecdotal reports suggest that adolescent males consume large quantities of food to meet the growth demands of pubertal development. However, limited experimental data exist to support this impression.

OBJECTIVE

The objective was to measure energy intakes of youth at different pubertal stages.

DESIGN

Participants were 204 volunteers (50.5% male) aged 8-17 y. Pubertal development was categorized by physical examination into prepuberty (males: testes < 4 mL; females: Tanner breast stage 1), early-mid puberty (males: testes = 4-12 mL; females: Tanner breast stages 2-3), or late puberty (males: testes >12 mL; females: Tanner breast stages 4-5). Energy intake was measured as consumption from a 9835-kcal food array during 2 lunch time meals.

RESULTS

Males consumed more energy than did females across all pubertal stages (P < 0.001). Intake increased with pubertal development (P < 0.001), but the timing and magnitude of change varied by sex (P = 0.02). Males' unadjusted energy intake was greater in late puberty (mean +/- SE: 1955 +/- 70 kcal) than in prepuberty (1287 +/- 90 kcal) or early-mid puberty (1413 +/- 92 kcal) (P < 0.001). Females' unadjusted energy intake tended to be lower among prepubertal girls (905 +/- 140 kcal) than among females in early-mid puberty (1278 +/- 82 kcal, P = 0.07) or late puberty (1388 +/- 68 kcal, P = 0.01). After adjustment for fat-free mass, fat mass, height, overweight status, race, and meal instruction, the main effect of sex (P < 0.001) remained significant, but the effect of puberty was not significant (P = 0.66).

CONCLUSIONS

The observed intake patterns are congruent with known sexual dimorphisms for body composition, peak growth velocity, and pubertal development. Consistent with their higher energy requirements, males can consume significantly larger amounts of food than females, especially during later puberty. This trial was registered at clinicaltrials.gov as NCT00320177.

Variability in results from predicted resting energy needs as compared to measured resting energy expenditure in Korean children

Energy needs are influenced by many factors, including ethnicity. Multiple studies have shown that the accuracy of an energy prediction equation varies with the ethnic background of the study population. Therefore, it is crucial to identify the most accurate energy prediction equation to use for a given population. This study compared measured resting energy expenditure to results from commonly-used energy prediction equations to identify the most accurate equation to use for Korean children. Based on previous literature showing wide variation in accuracy of energy prediction equations in different ethnic groups, we hypothesized that results from measured- vs. predicted energy needs would be significantly different in this population. Subjects were 92 South Korean children (38 boys, 54 girls) age 7.7 +/- 2.7 years (mean +/- SD). Measurements included: resting metabolic rate (TrueOne 2400 metabolic cart), weight/height (digital scale/stadiometer); body fat (BIA, Inbody720), blood pressure (sphingomanometer), triceps skinfold thickness (MD-500 skinfold calipers), muscle mass (Heymsfield's formula) and body surface area (Dubois formula) calculations. Resting energy needs were predicted using the Harris-Benedict, WHO/NAO/FAO, Altman and Dittmer, Maffeis, and Schofield-HW equations, and the Dietary Reference Intake recommendations. Measured and predicted energy needs were significantly correlated (P < .001 for all; range R(2) = 0.54-0.56), yet significantly different for all equations studied (P < .05) except the Maffeis and Schofield-HW equations. Differences (means +/- SD) between measured vs. predicted energy needs ranged from 9.5 +/- 123.2 (Schofield-HW) to 199.6 +/- 132.7 (WHO/NAO/FAO) kcal/day, where a value closer to zero indicates increased accuracy of the prediction equation to correspond to measured energy needs. Although results from equations studied were significantly correlated with measured resting energy needs, notable discrepancies existed which, over time, could produce undesirable weight changes in Korean children.

Changes in resting energy expenditure and their relationship to insulin resistance and weight gain: a longitudinal study in pre-pubertal children (EarlyBird 17)

BACKGROUND & AIMS

In adults, adjustments in resting energy expenditure (REE) are used to defend energy balance against disturbance caused by over-and under-nutrition, and may be linked to changes in insulin resistance and leptin. Little is known of these associations in children. Our aim was to test the hypothesis that long-term weight gain in children is met with adaptive changes in resting energy expenditure, mediated by insulin resistance and/or leptin.

METHODS

REE by indirect calorimetry, anthropometry, body composition by DEXA, insulin resistance (HOMA-IR) and serum leptin were measured annually in 232 children from the age of 7-10 y.

RESULTS

REE rose from 7 to 10 y, and the rise exceeded that predicted by the concurrent rise in fat and fat-free mass by 184 kcal/day in the boys and by 160 kcal/day in the girls. However, there were no significant relationships in either gender between this 'excess' rise in REE and change in body composition (r < or = 0.08, p > or = 0.42). The rise in both boys and girls was associated with, but not explained by, a rise in insulin resistance (p < or = 0.002). There was no association with serum leptin (p > or = 0.32).

CONCLUSIONS

The data do not support the hypothesis of adaptive changes in REE in pre-pubertal children, and insulin resistance explains very little of the pre-pubertal rise in REE. The rise in REE beyond that explained by changes in body composition may reflect an increase in energy requirements prior to puberty.

A prospective study of loss of control eating for body weight gain in children at high risk for adult obesity

OBJECTIVE

Limited data suggest that disordered-eating may predispose children to excessive weight gain. We investigated the relationship between baseline responses to the Eating Disorder Examination adapted for Children (ChEDE) and change in BMI (kg/m(2)) in children at high risk for adult obesity.

METHOD

Children (6-12 years) were administered the ChEDE to assess loss of control (LOC) eating, dietary restraint, and eating, shape, and weight concern. Height and weight were measured at baseline and annually.

RESULTS

Between July, 1999, and August, 2007, 772 measurements were obtained from 143 children over 4.5 +/- 1.9 years. LOC eating predicted an increased rate of BMI growth over time (p = .02). Compared with children without LOC, those reporting LOC gained an additional mean 2.4 kg of weight per year.

CONCLUSION

LOC is a salient predictor of weight gain during middle childhood. Interventions that decrease LOC eating should be evaluated for their ability to prevent excessive pediatric weight gain.

[Evaluation of energy expenditure in children. Physiological and clinical implications and measurement methods]

The present article reviews the importance of the study of energy metabolism and its methods of assessment in children. Classically, energy requirements have been assessed by predictive equations based on anthropometric data. However, there are several physiologic and pathogenic states that may cause discrepancies between estimated and real values and consequently direct measurements of energy expenditure should be used. The gold standard to assess total energy expenditure during prolonged periods is the doubly labeled water method, which is mainly used for research studies. The best approach for resting energy expenditure determination in the clinical setting is indirect calorimetry. However, this method does not provide data on energy consumption under free-living conditions and its use in some critical care patients is restricted by technical limitations. Several other approaches to assess activity have been developed, based on heart rate, body temperature measurements, motion sensors and combined methods.

Longitudinal analysis of resting energy expenditure in patients with cystic fibrosis

OBJECTIVE

To assess whether elevated resting energy expenditure (REE) in female patients with cystic fibrosis (CF) persists longitudinally during late childhood and puberty.

STUDY DESIGN

REE and body composition were measured 3 times in 2 years in 86 children with CF. Pubertal status, bacterial colonization, liver disease, pancreatic and pulmonary function, and genotype were determined, and linear mixed model analyses were used to determine predictors and changes in REE longitudinally.

RESULTS

REE did not change with time allowing for fat free mass, pancreatic insufficiency (PI), or severe mutations. Pulmonary function and liver disease were not significant predictors of REE. Percentage predicted REE compared with control data was higher (P = .002) in female patients with CF (109.5%) and lower in male patients with CF (104%) and persisted with time. In post-menarchal female patients with CF, REE adjusted for fat free mass was 366 kJ/d lower than in pre-menarchal female patients, but still 112% predicted.

CONCLUSIONS

This longitudinal study demonstrates that REE is elevated in patients with CF with PI and severe mutations. The elevation of percentage predicted REE was greater in female patients than male patients and persisted for 2 years, and during pubertal maturation, independent of pulmonary and liver disease. These results highlight the need for a high-energy diet throughout childhood and adolescence, particularly in female patients with PI.

Physical activity in preschoolers: understanding prevalence and measurement issues

Accurate physical activity quantification in preschoolers is essential to establish physical activity prevalence, dose-response relationships between activity and health outcomes, and intervention effectiveness. To date, best practice approaches for physical activity measurement in preschool-aged children have been relatively understudied. This article provides a review of physical activity measurement tools for preschoolers, an overview of measurement of preschoolers' physical activity, and directions for further research. Electronic and manual literature searches were used to identify 49 studies that measured young children's physical activity, and 32 studies that assessed the validity and/or reliability of physical activity measures with preschool-aged children. While no prevalence data exist, measurement studies indicate that preschool children exhibit low levels of vigorous activity and high levels of inactivity, boys are more active than girls, and activity patterns tend to be sporadic and omnidirectional. As such, measures capable of capturing differing activity intensities in very short timeframes and over multiple planes are likely to have the most utility with this population. Accelerometers are well suited for this purpose, and a number of models have been used to objectively quantify preschoolers' physical activity. Only one model of pedometer has been investigated for validity with preschool-aged children, showing equivocal results. Direct observation of physical activity can provide detailed contextual information on preschoolers' physical activity, but is subjective and impractical for understanding daily physical activity. Proxy-report questionnaires are unlikely to be useful for determining actual physical activity levels of young children, and instead may be useful for identifying potential correlates of activity. Establishing validity is challenging due to the absence of a precise physical activity measure, or 'criterion', for young children. Both energy expenditure (EE) and direct observation have been considered criterion measures in the literature; however, EE is influenced by multiple variables, so its use as a physical activity 'criterion' is not ideal. Also, direct observation is inherently subjective, and coding protocols may result in failure to capture intermittent activity, thereby limiting its utility as a physical activity criterion. Accordingly, these issues must be taken into account where EE or direct observation are used to validate physical activity instruments. A combination of objective monitoring and direct observation may provide the best standard for the assessment of physical activity measurement tools. Ideally, the convergent validity of various physical activity tools should be investigated to determine the level of agreement between currently available measures. The correlational approaches commonly employed in the assessment of physical activity measures do not reveal this relationship, and can conceal potential bias of either measure.

Ethnicity, energy expenditure and obesity: are the observed black/white differences meaningful?

PURPOSE OF REVIEW

Recent studies have suggested that black individuals have lower energy expenditure than whites. Many investigators hypothesized that this is why black women experience higher rates of obesity than white women. These findings initiated much research on race as a primary biological determinant of obesity and energy expenditure as a potential pathway. Race is a difficult construct to use in biomedical research.

RECENT FINDINGS

Recent findings have included: an explanation for the lower resting energy expenditure observed among black adults, data showing that relative resting energy expenditure may not be a significant predictor of weight change in African-origin populations, and inconsistent data on the role of activity energy expenditure as a determinant of children's weight change.

SUMMARY

The data suggest that black individuals have lower resting energy expenditure and possibly activity energy expenditure than white individuals. The lower resting energy expenditure is probably caused by a smaller mass of high metabolically active organs. It is unlikely that increased weight gain is associated with lower resting energy expenditure or activity among blacks, because no association has been found within populations. Clinically, it is important to focus on personal modifiable risk factors, e.g., energy intake and physical activity levels.

Resting energy expenditure in females with cystic fibrosis: Is it affected by puberty?

OBJECTIVE

The aims of this study were to determine the effect of puberty and the menstrual cycle on resting energy expenditure (REE) in females with cystic fibrosis (CF).

DESIGN

Cross-sectional study. All participants had measurements of REE, anthropometry and pubertal staging. The measurements in the postmenarche group were carried out both in the follicular and luteal phases of their menstrual cycle.

SETTING

CF outpatient clinic at the Children's Hospital at Westmead.

SUBJECTS

Fifty-six females with CF and pancreatic insufficiency (13 postmenarche) were recruited from the hospital clinic and 63 controls (21 postmenarche) were recruited through families and friends of hospital staff.

RESULTS

Females with CF had a higher REE than controls (111.6+/-12.8% of predicted from controls P<0.001). There was a significant effect of menarche on REE with a decrease in the postmenarche -470 kJ/24 h compared with premenarche after adjustment for fat-free mass, fat mass and group (control or CF). There was no difference in REE between the follicular and luteal phases for either CF or controls.

CONCLUSIONS

Females with CF had raised REE that appeared to be independent of menarche. This study implies all females with CF and pancreatic insufficiency may need more intensive dietary management, owing to raised REE, to maintain growth and nutritional status, and possibly improve survival.

Risk Factors for Childhood Obesity in Elementary School‐Age Taiwanese Children

A cross-sectional study design was used to examine factors that contribute to high relative weight in children in Taiwan. A total sample of 331 Chinese children (ages 7 and 8) and their parents participated in the study. Parents completed questionnaires regarding demographic information, family functioning, parenting styles, physical activity, and dietary intake. Children completed physical fitness tests and questionnaires regarding physical activity, dietary intake, coping strategies, and self-esteem. The weight-for-length index was used to measure children's relative weight. The findings revealed that four variables contributed to higher weight-for-length index in boys compared with girls and explained 37.7% of the variance: high maternal body mass index, poor aerobic capacity, healthy family role functioning, and poor family affective responsiveness. Two variables were found to contribute to higher weight-for-length index in girls and explained 12.8% of the variance: high household income and high maternal body mass index. Taken together, the results indicate the importance of assessment of children's weight status, maternal weight status, and family functioning as part of routine child health care and the need for developmentally appropriate and gender-specific approaches to prevent childhood obesity.

The conceptual framework for estimating food energy requirement

Objective

In anticipation of the revision of the 1985 Food and Agricultural Organization/World Health Organization/United Nations University (FAO/ WHO/UNU) Expert Consultation Report on ‘Energy and Protein Requirements’, recent scientific knowledge on the principles underlying the estimation of energy requirement is reviewed.

Design

This paper carries out a historical review of the scientific rationale adopted by previous FAO/WHO technical reports on energy requirement, discusses the concepts used in assessing basal metabolic rate (BMR), energy expenditure, physical activity level (PAL), and examines current controversial areas. Recommendations and areas of future research are presented.

Conclusions

The database of the BMR predictive equations developed by the 1985 FAO/WHO/UNU Expert Consultation Report on Energy and Protein Requirements needs updating and expansion, applying strict and transparent selection criteria. The existence of an ethnic/tropical factor capable of affecting BMR is not supported by the available evidence. The factorial approach for the calculation of energy requirement, as set out in the 1985 report, should be retained. The estimate should have a normative rather than a prescriptive nature, except for the allowance provided for extra physical activity for sedentary populations, and for the prevention of non-communicable chronic diseases. The estimate of energy requirement of children below the age of 10 years should be made on the basis of energy expenditure rather than energy intake. The evidence of the existence of an ethnic/tropical factor is conflicting and no plausible mechanism has as yet been put forward.

Effects of exercise training on resting metabolic rate in postmenopausal African American and Caucasian women

Ambiguous findings have been reported in previous studies concerning the relationships between resting metabolic rate (RMR), effects of exercise, and race in postmenopausal women. The purposes of this study were (1) to determine the effect of exercise training on RMR in postmenopausal women and (2) to determine whether this effect is different by race. We analyzed data from 24 African American (AA) (age, 56.3 +/- 5.0 years) and 23 Caucasian (CA) (age, 58.6 +/- 6.1 years) women. RMR was measured by indirect calorimetry after an overnight fast. Subjects completed tests of maximal exercise with metabolic measurements, waist to hip ratio, and body composition. At the completion of all tests, each subject was randomly assigned to either the exercise training or the control group. Aerobic exercise was performed 3 to 4 days per week for 6 months. Intensity was set at 70% to 85% maximal heart rate for 45 to 60 minutes per session. Both AA and CA exercise groups had a significant decrease (P < .05) in body weight (kilograms), percent body fat, and body mass index (BMI) and an increase in aerobic capacity, whereas the control groups did not change. There were no race effects. AA women exhibited significantly lower values than CA women for measured RMR (P < .05). The RMR (kilojoules) of the AA women (both control and exercise groups) decreased over time (P < .05), whereas the RMR of the CA women did not change. Adjusting RMR for BMI or for changes in lean body mass and fat mass did not alter these results. In conclusion, this 6-month endurance-training program did not affect RMR in these postmenopausal women, as RMR did not change in CA women, but decreased significantly over time in both groups of AA women. The factors that contribute to these findings should be the focus of future studies.

Binge eating in overweight treatment-seeking adolescents

OBJECTIVE

To examine the frequency and recency of binge eating in relation to psychopathology in overweight, treatment-seeking adolescents.

METHODS

We investigated psychological correlates of the frequency and recency of reported loss of control (LOC) eating episodes in 160 overweight (body mass index [BMI]: 40.7 +/- 8.8 kg/m(2)) adolescents. On the basis of the responses to the eating disorder examination (EDE), participants were categorized into one of four groups: full-syndrome binge eating disorder (BED); recent but infrequent binge eating (episodes within the 3 months before interview; RECENT-BINGE); remote and infrequent LOC eating (episodes occurring >3 months before assessment; PAST-LOC), or no history of LOC episodes (NE).

RESULTS

The BED group reported higher EDE scores (global, p < .01), and more negative mood and anxiety than all other groups (p's < .01). Compared with NE, RECENT-BINGE also reported more anxiety and higher EDE scores (p's < .01).

CONCLUSIONS

Overweight, treatment-seeking adolescents with BED are clearly distinguishable from teens without the disorder on measures of eating-related psychopathology, mood, and anxiety. RECENT-BINGE, but not PAST-LOC, is also associated with significantly greater eating-related and general psychopathology.

Small organs with a high metabolic rate explain lower resting energy expenditure in African American than in white adults

BACKGROUND

African Americans have a lower resting energy expenditure (REE) relative to fat-free mass (FFM) than do whites. Whether the composition of FFM at the organ-tissue level differs between African Americans and whites and, if so, whether that difference could account for differences by race in REE are unknown.

OBJECTIVE

The objectives were to quantify FFM in vivo in women and men at the organ-tissue level and to ascertain whether the mass of specific high-metabolic-rate organs and tissues differs between African Americans and whites and, if so, whether that difference can account for differences in REE.

DESIGN

The study was a cross-sectional evaluation of 64 women (n = 34 African Americans, 30 whites) and 35 men (n = 8 African Americans, 27 whites). Magnetic resonance imaging measures of liver, kidney, heart, spleen, brain, skeletal muscle, and adipose tissue and dual-energy X-ray absorptiometry measures of fat and FFM were acquired. REE was measured by using indirect calorimetry.

RESULTS

The mass of selected high-metabolic-rate organs (sum of liver, heart, spleen, kidneys, and brain) after adjustment for fat, FFM, sex, and age was significantly (P < 0.001) smaller in African Americans than in whites (3.1 and 3.4 kg, respectively; x +/- SEE difference: 0.30 +/- 0.06 kg). In a multiple regression analysis with fat, FFM, sex, age, and race as predictors of REE, the addition of the total mass rendered race nonsignificant.

CONCLUSIONS

Racial differences in REE were reduced by >50% and were no longer significant when the mass of specific high-metabolic-rate organs was considered. Differences in FFM composition may be responsible for the reported REE differences.

A prospective study of psychological predictors of body fat gain among children at high risk for adult obesity

OBJECTIVE

Limited data suggest that psychological factors, including binge eating, dieting, and depressive symptoms, may predispose children to excessive weight gain. We investigated the relationship between baseline psychological measures and changes in body fat (measured with dual-energy x-ray absorptiometry) over time among children thought to be at high risk for adult obesity.

METHODS

A cohort study of a convenience sample of children (age: 6-12 years) recruited from Washington, DC, and its suburbs was performed. Subjects were selected to be at increased risk for adult obesity, either because they were overweight when first examined or because their parents were overweight. Children completed questionnaires at baseline that assessed dieting, binge eating, disordered eating attitudes, and depressive symptoms; they underwent measurements of body fat mass at baseline and annually for an average of 4.2 years (SD: 1.8 years).

RESULTS

Five hundred sixty-eight measurements were obtained between July 1996 and December 2004, for 146 children. Both binge eating and dieting predicted increases in body fat. Neither depressive symptoms nor disturbed eating attitudes served as significant predictors. Children who reported binge eating gained, on average, 15% more fat mass, compared with children who did not report binge eating.

CONCLUSIONS

Children's reports of binge eating and dieting were salient predictors of gains in fat mass during middle childhood among children at high risk for adult obesity. Interventions targeting disordered eating behaviors may be useful in preventing excessive fat gain in this high-risk group.

Relação entre diferentes índices de atividade física e preditores de adiposidade em adolescentes de ambos os sexos

OBJETIVO: Determinar a relação entre diferentes índices de atividade física e preditores de adiposidade em adolescentes de ambos os sexos. MÉTODOS: Foram avaliadas 111 crianças (57 meninos e 54 meninas), com idade média de 11,62 ± 0,72. Como preditores de adiposidade foram determinados o IMC, percentagem de gordura corporal e a relação cintura/quadril (RCQ). Quanto aos indicadores de atividade física, calcularam-se o gasto energético total (GET), nível de atividade física habitual (NAFH), nível de atividade física (NAF) e gasto energético com atividade física (GEat) através do questionário de Bouchard e, para a taxa metabólica basal (TMB), a equação de Schofield-HW. RESULTADOS: A amostra apresentou diferenças significativas entre os sexos para idade, % de gordura corporal, RCQ, NAFH, NAF, TMB com p < 0,05. Para os meninos o GET, NAF, TMB e GEat apresentaram correlação significativa com o IMC (r = 0,86; r = 0,70; r = 0,91; r = 0,78) e % de gordura (r = 0,78; r = 0,61; r = 0,90; r = 0,70) com p < 0,01, respectivamente, e o GET, TMB, GEat apresentaram correlação significativa com o RCQ (r = 0,28; r = 0,45 e r = 0,28) com p < 0,05. Para as meninas o GET, NAF, TMB, GEat apresentaram valores significativos com o IMC (r = 0,86; r = 0,82; r = 0,78; r = 0,85); em % de gordura todos os indicadores GET, NAFH, NAF, TMB e GEat foram significativos (r = 0,73; r = -0,29; r = 0,66; r = 0,74; r = 0,70) com p < 0,05. CONCLUSÃO: Os diferentes indicadores de nível de atividade física apresentaram significativa correlação com os preditores de adiposidade com exceção do RCQ para as meninas. O aumento da massa corporal demonstrou relação significância com o aumento do dispêndio energético em função da maior necessidade de energia para movimentar o corpo.

Longitudinal changes in energy expenditure in girls from late childhood through midadolescence

BACKGROUND

Longitudinal data on energy expenditure in children and adolescents are scarce.

OBJECTIVE

The purpose of this study was to examine changes in energy expenditure and physical activity in girls from late childhood through midadolescence.

DESIGN

We measured total energy expenditure (TEE) by doubly labeled water, resting metabolic rate (RMR) by indirect calorimetry, body composition by 18O dilution, and time spent in activity by an activity diary in 28 initially nonobese girls at approximately 10, approximately 12, and approximately 15 y of age. Changes with age in TEE, RMR, and activity energy expenditure (AEE), both in absolute terms and in adjusted analyses, and in physical activity level (PAL) and time spent sleeping, being sedentary, and in moderate and vigorous activity were evaluated by mixed-model repeated-measures analyses.

RESULTS

Absolute TEE and AEE increased significantly from age 10 to age 15 y (P < 0.0001 for both). Absolute RMR at ages 12 and 15 y did not differ significantly, despite significant increases in fat-free mass and fat mass between the visits. PAL was significantly higher (P < 0.0001) at age 15 y than at age 10 or 12 y, whereas time spent being sedentary increased significantly from age 10 to age 15 y (P < 0.001), and AEE adjusted for fat-free mass appeared to decrease over the same interval.

CONCLUSION

Conclusions drawn regarding changes with age in physical activity depend on the measure of physical activity assessed.

Prediction equations for resting energy expenditure in overweight and normal-weight black and white children

BACKGROUND

Accurate estimation of children's resting energy expenditure (REE) is important for planning dietary therapy.

OBJECTIVE

Our objective was to compare the utility of 5 REE prediction equations in a diverse sample of young children.

DESIGN

REE was obtained in 502 black and white girls and boys aged 6-11 y by using indirect calorimetry at 4 US sites. Measured REE and REE predicted from the equations were compared.

RESULTS

None of the equations provided both accurate and unbiased estimates of REE. Two new sets of sex-specific equations including race as a factor were generated and evaluated. One set used easily measured variables-females: REE = 0.046 x weight - 4.492 x 1/height(2) - 0.151 x race + 5.841; males: REE = 0.037 x weight - 4.67 x 1/height(2) - 0.159 x race + 6.792-and accounted for 72% and 69%, respectively, of REE variance. The other set used body-composition variables-females: REE = 0.101 x fat-free mass + 0.025 x fat mass + 0.293 x height(3) - 0.185 x race + 1.643; males: REE = 0.078 x fat-free mass + 0.026 x fat mass - 2.646 x 1/height(2) - 0.244 x race + 4.8-and accounted for 75% and 71%, respectively, of REE variance. When split by race and adiposity, the small bias generated could be corrected to within 0.25 MJ (60 kcal) of the mean measured value.

CONCLUSION

Sex-specific equations must take race into account to predict REE adequately in children.

Body-composition differences between African American and white women: relation to resting energy requirements

BACKGROUND

Body composition differs between African American (AA) and white women, and the resting metabolic rate (RMR) is likely to be lower in AA women than in white women.

OBJECTIVE

We tested 2 hypotheses: that AA women have a greater proportion of low-metabolic-rate skeletal muscle (SM) and bone than do white women and that between-race musculoskeletal differences are a function of body weight.

DESIGN

Hypothesis 1 was tested by comparing SM, bone, adipose tissue, and high-metabolic-rate residual mass across 22 pairs of matched AA and white women. Magnetic resonance imaging and dual-energy X-ray absorptiometry were used to partition weight into 4 components, and RMR was both calculated from tissue-organ mass and measured. Hypothesis 2 was evaluated by measuring SM, bone, fat, and residual mass in 521 AA and white women with the use of dual-energy X-ray absorptiometry alone.

RESULTS

Hypothesis 1: AA women had greater SM ( +/- SD group difference: 1.52 +/- 2.48 kg; P < 0.01) and musculoskeletal mass (1.72 +/- 2.66 kg; P < 0.01) than did white women. RMR calculated from body composition and measured RMR did not differ; RMR estimated by both approaches tended to be lower (approximately 160 kJ/d) in AA women than in white women. Hypothesis 2: SM was significantly correlated with weight, height, age, and race x weight interaction; greater SM in the AA women was a function of body weight.

CONCLUSIONS

Lower RMRs in AA women than in white women are related to corresponding differences in the proportions of heat-producing tissues and organs, and these race-related body-composition differences increase as a function of body weight.

Time to reevaluate the therapeutic use of calcitonin and biological role attributable to parafollicular (C) cells

There is rich anecdotal evidence that calcitonin significantly increases bone mineral density and reduces fracture risk. However, observation in a previous study of an increased bone formation in calcitonin-deficient mice has led us to reevaluate the therapeutic use of calcitonin and to investigate the primary role of parafollicular (C) cells of the thyroid gland. We found that C cells are involved mainly in the regulation of follicular cell activity in a paracrine manner and in doing so they may regulate the growth rate in newborn by affecting the thyroid hormone levels in the early postnatal period. In the light of reports that showed thyroid physiology is different between populations and it is affected by environmental factors we suggested that C cells may be involved in population differences in thyroid physiology and environmental adaptation. We conclude that C cells may facilitate the adaptation of the follicular cells to environmental changes, enabling more effective coordinated functions of the body and producing variations between populations.

Efficacy of orlistat as an adjunct to behavioral treatment in overweight African American and Caucasian adolescents with obesity-related co-morbid conditions

This pilot study compared the efficacy of orlistat as an adjunctive treatment for obesity between African American and Caucasian adolescents. Twenty obese adolescents with obesity-related co-morbid conditions underwent measurements of body composition, glucose homeostasis by frequently sampled intravenous glucose tolerance test (FSIGT), and fasting lipids before and after 6 months treatment with orlistat 120 mg tid in conjunction with a comprehensive behavioral program. Weight (p < 0.05), BMI (p < 0.001), total cholesterol (p < 0.001), LDL cholesterol (p < 0.001), fasting insulin (p < 0.02) and fasting glucose (p < 0.003) were lower after treatment. Insulin sensitivity, measured during the FSIGT, improved significantly (p < 0.02), as did fasting indices such as the homeostasis model assessment for insulin resistance (p < 0.01). African American subjects exhibited significantly less improvement in weight (p < 0.05), BMI (p < 0.01), waist circumference (p = 0.03), and insulin sensitivity (p = 0.05). Improvements in cholesterol were not significantly different between African Americans and Caucasians. We conclude that Caucasians lost more weight and had greater improvements in insulin sensitivity than African Americans, but both exhibited improvements in plasma lipids. The true benefit of orlistat treatment over a comprehensive behavioral program remains to be determined in placebo-controlled trials.

Does menarche mark a period of elevated resting metabolic rate?

Resting metabolic rate (RMR) and body composition were measured in 44 initially nonoverweight girls at three time points relative to menarche: premenarche (Tanner stage 1 or 2), menarche (+/-6 mo), and 4 yr after menarche. Mean absolute RMR was 1,167, 1,418, and 1,347 kcal/day, respectively. Absolute RMR was statistically significantly higher at menarche than at 4 yr after menarche despite statistically significantly less fat-free mass (FFM) and fat mass (FM), suggesting an elevation in RMR around the time of menarche. The pattern of change in RMR, adjusted for FFM, log transformed FM, age, race, parental overweight, and two interactions (visit by parental overweight, parental overweight by FFM), was also considered. Adjusted RMR did not differ statistically between the visits for girls with two normal-weight parents. For girls with at least one overweight parent, adjusted RMR was statistically significantly lower 4 yr after menarche than at premenarche or menarche. Thus parental overweight may influence changes that occur in RMR during adolescence in girls.

Larger mass of high-metabolic-rate organs does not explain higher resting energy expenditure in children

BACKGROUND

Children have a high resting energy expenditure (REE) relative to their body weight. The decline in REE during growth may be due to changes in body composition or to changes in the metabolic rate of individual organs and tissues.

OBJECTIVES

The goals were to quantify body-composition components in children at the organ-tissue level in vivo and to determine whether the observed masses 1) account for the elevated REE in children and 2) account, when combined with specific organ-tissue metabolic constants, for children's REE.

DESIGN

This was a cross-sectional evaluation of 15 children (aged 9.3 +/- 1.7 y) and 13 young adults (aged 26.0 +/- 1.8 y) with body mass indexes (in kg/m(2)) < 30. Magnetic resonance imaging-derived in vivo measures of brain, liver, kidney, heart, skeletal muscle, and adipose tissue were acquired. REE was measured by indirect calorimetry (REE(m)). Previously published organ-tissue metabolic rate constants were used to calculate whole-body REE (REE(c)).

RESULTS

The proportion of adipose-tissue-free mass as liver (3.7 +/- 0.5% compared with 3.1 +/- 0.5%; P < 0.01) and brain (6.2 +/- 1.2% compared with 3.3 +/- 0.9%; P < 0.001) was significantly greater in children than in young adults. The addition of brain and liver mass significantly improved the model but did not eliminate the role of age. REE(c) with published metabolic coefficients underestimated REE(m) (REE(c) = 3869 +/- 615 kJ/d; REE(m) = 5119 +/- 769 kJ/d; P < 0.001) in children.

CONCLUSION

The decline in REE during growth is likely due to both a decrease in the proportion of some of the more metabolically active organs and tissues and changes in the metabolic rate of individual organs and tissues.

Evaluation of body composition: practical guidelines

The measurement of body composition in the truest sense allows for the estimation of body tissues, organs, and their distributions in living persons without inflicting harm. It is important to recognize that there is no single measurement method that is error-free. Furthermore, bias can be introduced if a measurement method makes assumptions related to body composition proportions and characteristics that are inaccurate across different populations. Some methodologic concerns include hydration of fat-free body mass changes with age and differences across ethnic groups [73]; the density of fat-free body mass changes with age and differences between men and women [74, 75]; total body potassium decreases with age [73] and fatness [76] and differences between African Americans and Caucasians [77]; the mass of skeletal muscle differences across race group [63]; and VAT differences across sex [78] and race [67, 79, 80] groups, independent of total adiposity. These between-group differences influence the absolute accuracy of methods for estimating fatness or FFM that involve the two-compartment model approach. The clinical significance of the body compartment to be measured should be determined before a measurement method is selected, because the more advanced techniques are less accessible and more costly.

Relation of body composition, parental overweight, pubertal stage, and race-ethnicity to energy expenditure among premenarcheal girls

BACKGROUND

Previous studies assessed the influence of parental weight status, sexual maturation, race-ethnicity, and energy expenditure among children, but few examined these issues comprehensively.

OBJECTIVE

The objective was to determine whether differences in energy expenditure among premenarcheal girls are related to the pubertal stage and the race-ethnicity of the girls or to the weight status of their parents.

DESIGN

We measured the body composition and the energy expenditure of 196 nonobese girls enrolled in a longitudinal study. Total body water was measured by the isotopic dilution of (18)O water. We measured resting metabolic rate with the use of indirect calorimetry and daily energy expenditure by the doubly labeled water method. We used established criteria to determine sexual maturation. Parental weight status was based on body mass index.

RESULTS

Resting metabolic rate was higher among girls with >or=1 overweight parent than among girls with 2 normal-weight parents. Total energy expenditure was also higher among girls with >or=1 overweight parent, but these results were of borderline significance. We found no effect of pubertal stage on resting metabolic rate. Nonresting energy expenditure was significantly lower among pubertal girls than among prepubertal girls. After adjustments for age and body composition, we noted that resting metabolic rate, nonresting energy expenditure, and total energy expenditure were all significantly lower among black girls than among white girls.

CONCLUSIONS

Differences in resting metabolic rate and total energy expenditure among premenarcheal girls were associated with parental weight status and the girls' race-ethnicity, whereas differences in nonresting energy expenditure were associated with pubertal stage and race-ethnicity. Whether the observed differences in energy expenditure persist after puberty and predict weight gain during puberty awaits the results of longitudinal analyses.

Assessing risk factors for obesity between childhood and adolescence: II. Energy metabolism and physical activity

OBJECTIVE

To assess the effect of energy expenditure, including resting metabolic rate (RMR), total energy expenditure (TEE), and activity energy expenditure (AEE), as well as substrate oxidation (respiratory quotient [RQ]), on the development of obesity in a large cohort of Native American children with a high propensity for obesity.

METHODS

During the summer months of 1992 to 1995 and again 5 years later, 138 (65 boys and 73 girls) 5-year-old Pima Indian children were studied. At baseline and follow-up, height and weight were measured; body composition was assessed with the use of 18O dilution; RMR and RQ were assessed with the use of indirect calorimetry; TEE was measured with the use of the doubly-labeled water method; and AEE was calculated (TEE - [RMR + 0.1 x TEE]). In addition, an activity questionnaire was used to assess participation in sporting activities as well as television viewing during the previous year. Linear regression models were used to assess the effects of the baseline variables on the development of obesity.

RESULTS

Pima Indian children were markedly overweight at both 5 and 10 years of age. Cross-sectionally, percentage of body fat and body weight at 5 and 10 years of age were negatively correlated with sports participation and positively correlated with television viewing. Most important, there was a marked change in the correlation between body size and activity between 5 and 10 years of age: at age 5 years, weight was positively correlated with AEE and PAL, but at age 10 years, the correlation with AEE was lost and that with PAL was negative. However, prospectively, none of the variables measured at baseline was a predictor of percentage of body fat at age 10 years after adjustment for percentage of body fat at age 5 years.

CONCLUSIONS

At age 5 years, obesity is associated with decreased participation in sports and increased television viewing but not with a decreased PAL. At age 10 years, obesity is associated with decreased participation in sports, increased television viewing, and a decreased PAL, suggesting that a decrease in PAL in free-living conditions seems to follow, not precede, the development of obesity.

Prepubertal Asians have less limb skeletal muscle

Skeletal muscle mass in prepubertal Asian children has not been examined previously. The aims of this study were to test the hypotheses that 1) prepubertal Asians have less appendicular skeletal muscle (ASM) mass compared with African-Americans and Caucasians, and 2) ASM is less in prepubertal Asian girls compared with Asian boys. ASM was estimated by using dual-energy X-ray absorptiometry in healthy prepubertal girls (n = 170) and boys (n = 166). The results showed that, after adjusting for age, height, and body weight, 1) Asian girls and boys had less amounts of ASM than African-Americans (P < 0.001); 2) Asian girls had less amounts of ASM than Caucasian girls (P = 0.004); 3) there was a trend towards less ASM in Asian compared with Caucasian boys (P = 0.07); 4) and Asian girls had significantly less ASM than Asian boys (P < 0.001). This study indicates that skeletal muscle mass as a fraction of body weight is smaller in Asian compared with African-American and Caucasian children.

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.