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.

Relationship of pressure to be thin with gains in body weight and fat mass in adolescents.

BACKGROUND: Sociocultural pressure to be thin is commonly reported by adolescents; yet, to what extent such pressure is associated with weight gain has not been evaluated longitudinally. OBJECTIVE: Examine whether pressure to be thin was positively associated with weight and fat gain in adolescents. METHODS: Participants were 196 healthy adolescent (age 15 ± 1 years old) girls (65%) and boys of varying weights (BMI 25 ± 7 kg/m2 ) studied at baseline and 1-year follow-up. At baseline, adolescents and their mothers reported pressure to be thin by questionnaire. At baseline and follow-up, BMI was calculated, and fat mass was assessed with air displacement plethysmography. Multiple regression was used to examine associations between baseline pressure to be thin and 1-year changes in BMI and fat mass. RESULTS: Accounting for multiple covariates, including baseline BMI or fat, adolescent-reported pressure from parents and peers and mother-reported pressure toward their teen were associated with greater gains in either adolescent BMI or fat (ps < .05). Adolescent weight status was a moderator of multiple effects (ps < .05). CONCLUSIONS: Parental and peer pressure to be thin were associated with increases in BMI and fat mass during adolescence, particularly in heavier adolescents. Further research is necessary to clarify how this association operates reciprocally and to identify underlying explanatory mechanisms.

A longitudinal study of serum insulin and insulin resistance as predictors of weight and body fat gain in African American and Caucasian children.

BACKGROUND: The influence of insulin and insulin resistance (IR) on children's weight and fat gain is unclear. OBJECTIVE: To evaluate insulin and IR as predictors of weight and body fat gain in children at high risk for adult obesity. We hypothesized that baseline IR would be positively associated with follow-up body mass index (BMI) and fat mass. SUBJECTS/METHODS: Two hundred and forty-nine healthy African American and Caucasian children aged 6-12 years at high risk for adult obesity because of early-onset childhood overweight and/or parental overweight were followed for up to 15 years with repeated BMI and fat mass measurements. We examined baseline serum insulin and homeostasis model of assessment-IR (HOMA-IR) as predictors of follow-up BMI Z-score and fat mass by dual-energy X-ray absorptiometry in mixed model longitudinal analyses accounting for baseline body composition, pubertal stage, sociodemographic factors and follow-up interval. RESULTS: At baseline, 39% were obese (BMI⩾95th percentile for age/sex). Data from 1335 annual visits were examined. Children were followed for an average of 7.2±4.3 years, with a maximum follow-up of 15 years. After accounting for covariates, neither baseline insulin nor HOMA-IR was significantly associated with follow-up BMI (Ps>0.26), BMIz score (Ps>0.22), fat mass (Ps>0.78) or fat mass percentage (Ps>0.71). In all models, baseline BMI (P<0.0001), body fat mass (P<0.0001) and percentage of fat (P<0.001) were strong positive predictors for change in BMI and fat mass. In models restricted to children without obesity at baseline, some but not all models had significant interaction terms between body adiposity and insulinemia/HOMA-IR that suggested less gain in mass among those with greater insulin or IR. The opposite was found in some models restricted to children with obesity at baseline. CONCLUSIONS: In middle childhood, BMI and fat mass, but not insulin or IR, are strong predictors of children's gains in BMI and fat mass during adolescence.

Serum leptin and loss of control eating in children and adolescents.

BACKGROUND: Both insufficiency and resistance to the actions of the adipocyte-derived hormone leptin promote hunger, increased food intake and greater body weight. Some studies suggest that adults reporting binge eating have increased serum leptin compared with those without binge eating, even after adjusting for the greater adiposity that characterizes binge eaters. Pediatric binge or loss of control (LOC) eating are prospective risk factors for excessive weight gain and may predict development of metabolic abnormalities, but whether LOC eating is associated with higher leptin among children is unknown. We therefore examined leptin and LOC eating in a pediatric cohort. METHODS: A convenience sample of 506 lean and obese youth (7-18 years) was recruited from Washington, DC and its suburbs. Serum leptin was collected after an overnight fast. Adiposity was measured by dual-energy X-ray absorptiometry or air displacement plethysmography. LOC eating was assessed by interview methodology. RESULTS: Leptin was strongly associated with fat mass (r=0.79, P<0.001). However, even after adjusting for adiposity and other relevant covariates, youth with LOC eating had higher serum leptin compared with those without LOC episodes (15.42±1.05 vs 12.36±1.04 ng ml(-1), P<0.001). Neither reported amount of food consumed during a recent LOC episode nor number of LOC episodes in the previous month accounted for differences in leptin (P>0.05). The relationship between LOC eating and leptin appeared to be significant for females only (P=0.002). CONCLUSIONS: Reports of LOC eating were associated with higher fasting leptin in youth, beyond the contributions of body weight. Prospective studies are required to elucidate whether LOC eating promotes greater leptin or whether greater leptin resistance may promote LOC eating.

Comparison of total energy expenditure between school and summer months.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Childhood obesity has increased 3 to 4 fold. Some children gain excess weight in summer. WHAT THIS STUDY ADDS: Total energy expenditure increases almost linearly with fat-free mass. A lower total energy expenditure was not detected in summer. OBJECTIVE: Recent data report that the youth experience greater weight gain during summer than during school months. We tested the hypothesis that a difference in total energy expenditure (TEE) between school and summer months exists and may contribute to summer weight gain. SUBJECTS AND METHODS: A secondary analysis was performed on cross-sectional TEE data from school-age, sedentary African-American and Caucasian youth based in or near the District of Columbia who were at-risk for adult obesity because they had body mass index (BMI) ≥ 85th percentile or had overweight parents. TEE was estimated from 18-O and deuterium measurements during 1-week intervals using urine samples collected after ingestion of doubly labelled water. Differences in summer- and school-time TEE were assessed using analysis of covariance. The data were adjusted for fat-free mass (FFM) as determined by deuterium dilution to adjust for the effect of body size on TEE. RESULTS: Data were collected from 162 youth (average age 10 ± 2 years, BMI 28 ± 8 kg m(-2) and BMI z-score 1.96 + 0.96). Of these, 96 youth had TEE measured during the school year (September-June); 66 different youths had TEE measured during summer months (June-August). After adjustment for FFM, average summertime TEE was 2450 ± 270 kcal d(-1) and average school-time TEE was 2510 ± 350 kcal d(-1) (P = 0.26). CONCLUSION: No difference in TEE was detected between the school year and the summer months. These data suggest that seasonal differences in youth weight gain are not necessarily due to differences in energy expenditures.

Pharmacotherapy for childhood obesity: present and future prospects.

Pediatric obesity is a serious medical condition associated with significant comorbidities during childhood and adulthood. Lifestyle modifications are essential for treating children with obesity, yet many have insufficient response to improve health with behavioral approaches alone. This review summarizes the relatively sparse data on pharmacotherapy for pediatric obesity and presents information on obesity medications in development. Most previously studied medications demonstrated, at best, modest effects on body weight and obesity-related conditions. It is to be hoped that the future will bring new drugs targeting specific obesity phenotypes that will allow clinicians to use etiology-specific, and therefore more effective, anti-obesity therapies.

Children's binge eating and development of metabolic syndrome.

BACKGROUND: Binge eating predisposes children to excessive weight gain. However, it is unknown if pediatric binge eating predicts other obesity-associated adverse health outcomes. OBJECTIVE: The objective of this study was to investigate the relationship between binge eating and metabolic syndrome (MetS) in children. METHOD: Children aged 5-12 years at high risk for adult obesity, either because they were overweight/obese when first examined or because their parents were overweight/obese, were recruited from Washington, DC and its suburbs. Children completed a questionnaire assessment of binge eating at baseline and underwent measurements of MetS components at baseline and at a follow-up visit approximately 5 years later. Magnetic resonance imaging was used to measure the visceral adipose tissue (VAT) in a subset. RESULTS: In all, 180 children were studied between July 1996 and August 2010. Baseline self-reported binge eating presence was associated with a 5.33 greater odds of having MetS at follow-up (95% confidence interval (CI): 1.47, 19.27, P=0.01). The association between binge eating and body mass index (BMI) only partially explained changes in MetS components: baseline binge eating predicted higher follow-up triglycerides, even after accounting for baseline triglycerides, baseline BMI, BMI change, sex, race, baseline age and time in study (P = 0.05). Also, adjusting for baseline VAT and demographics, baseline binge eating predicted greater follow-up L(2-3) VAT (P = 0.01). DISCUSSION: Children's reports of binge eating predicted development of MetS, worsening triglycerides and increased VAT. The excessive weight gain associated with children's binge eating partly explained its adverse metabolic health outcomes. Reported binge eating may represent an early behavioral marker upon which to focus interventions for obesity and MetS.

Construct validity of the emotional eating scale adapted for children and adolescents.

BACKGROUND: Emotional eating, defined as eating in response to a range of negative emotions, is common in youths. Yet, there are few easily administered and well-validated methods to assess emotional eating in pediatric populations. OBJECTIVE: The current study tested the construct validity of the Emotional Eating Scale (EES) Adapted for Children and Adolescents (EES-C) by examining its relationship to observed emotional eating at laboratory test meals. METHOD: A total of 151 youths (8-18 years) participated in two multi-item lunch buffet meals on separate days. They ate ad libitum after being instructed to 'eat as much as you would at a normal meal' or to 'let yourself go and eat as much as you want'. State negative affect was assessed immediately before each meal. The EES-C was completed 3 months, on average, before the first test meal. RESULTS: Among youths with high EES-C total scores, but not low EES-C scores, higher pre-meal state negative affect was related to greater total energy intake at both meals, with and without the inclusion of age, race, sex and body mass index (BMI) standard deviation as covariates (ps<0.03). DISCUSSION: The EES-C demonstrates good construct validity for children and adolescents' observed energy intake across laboratory test meals designed to capture both normal and disinhibited eating. Future research is required to evaluate the construct validity of the EES-C in the natural environment and the predictive validity of the EES-C longitudinally.

Assessing the body composition of 6-17-year-old Black and White girls in field studies.

The purpose of the study was to develop ethnic-specific equations for fat-free mass (FFM) from selected anthropometric dimensions and bioelectrical impedance measures of resistance (R) and reactance (Xc) for use in the NHLBI Growth and Heath Study. Using dual-energy X-ray absorptiometry measures of body composition as the dependent variable and field measures of body composition by anthropometry and bioelectrical impedance as the explanatory variables, ethnic-specific prediction equations were developed on a sample of girls representing a wide range of ages and BMI. The equations were cross-validated using (1) the Prediction of Sum of Squares (PRESS) statistic and (2) an independent sample of 20 girls of each race from a study conducted at the National Institute of Child Health and Human Development (NICHD). Subjects were 65 White and 61 Black girls 6-17 years of age. The best race-specific equations for FFM each explained 99% and 97% of the variance in the White and Black girls, respectively. Root mean square errors (RMSE) ranged from 1.14 to 1.95 kg. The equation for Black girls used Stature2/Resistance (R), weight, and reactance (Xc) as predictor variables; the equation for White girls used Stature2/R, weight, and triceps skinfold thickness. The results indicate that (1) equations to predict FFM in girls should be ethnic-specific and that (2) accurate values for TBF and %BF can be calculated from the predicted FFM.

Osteoarthritis: new insights. Part 1: the disease and its risk factors.

Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weight-bearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability.

Hypothalamic-pituitary-adrenal axis activity during exercise in African American and Caucasian women.

African American women have a greater prevalence of obesity than Caucasian women, but the reasons for this difference are not known. We have investigated whether activity of the hypothalamic-pituitary adrenal axis plays a role in this phenomenon. Previous studies have shown that plasma ACTH immunoreactivity (ACTH-IR) of African American women, measured after ovine CRH (oCRH) stimulation, is significantly greater than ACTH-IR of Caucasian women, but is not accompanied by greater plasma cortisol concentrations. Analysis by high pressure liquid chromatography has demonstrated that after oCRH stimulation, the plasma ACTH-IR of African American women contains many nonintact ACTH fragments not found in Caucasians. To determine whether these racial differences in ACTH-IR secretion are an artifact of exogenous oCRH administration or are also found after a physiological stimulus for ACTH secretion, we measured hormones of the hypothalamic-pituitary adrenal axis before and after a standardized, maximal exercise treadmill test in 16 African American and 19 Caucasian healthy women matched for age, socioeconomic status, and body mass index. The intensity of exercise performed was similar in the two groups, as determined by duration of exercise, perceived intensity of exertion, plasma lactate, maximal heart rate, and maximum oxygen uptake. Basal ACTH-IR measured by RIA or immunoradiometric assay and cortisol were similar in African Americans and Caucasians. Plasma ACTH-IR, measured 10 min after completion of exercise, was significantly greater in African Americans than in Caucasians [by RIA: mean +/- SD ACTH-IR, 47.1 +/- 30.9 vs. 25.4 +/- 16.7 pmol/L (P < 0.01); by immunoradiometric assay: ACTH-IR, 45.9 +/- 43.2 vs. 21.1 +/- 14.6 pmol/L (P < 0.05)]. However, plasma cortisol after exercise was not different (450.2 +/- 157.7 vs. 483.6 +/- 180.4 nmol/L; P = 0.57). We conclude that ACTH-IR is significantly greater in African American than in Caucasian women after intense exercise. The ACTH-IR of African Americans and Caucasians does not appear to be equipotent at adrenal melanocortin-2 receptors, because the greater ACTH-IR of African Americans does not lead to greater cortisol secretion. Whether some components of the ACTH-IR detected in African Americans affect signal transduction of the hypothalamic melanocortin-4 receptors implicated in body weight regulation and thus predispose African American women to weight gain without altering plasma cortisol remains to be determined.

Obesity: what mental health professionals need to know.

OBJECTIVE: Obesity is a highly prevalent condition with significant health implications. This report summarizes recent clinically relevant findings concerning the pathogenesis and treatment of obesity and considers their implications for psychiatric diagnosis and management. METHOD: The authors conducted selective reviews of the literature from the last 10 years. Topics included the biological and behavioral factors that contribute to the onset and maintenance of obesity, the relationship between obesity and psychiatric illness and treatment, and the questions of whether and how obesity should be treated. RESULTS: Genetic effects, some mediated by eating behavior, contribute importantly to the potential for obesity, the expression of which is promoted by environmental factors that increase the availability of calorically dense foods and discourage activity. There appear to be behaviorally distinct subsets of obese persons who display particular patterns of disordered eating and elevated rates of psychopathology. Treatment with psychotropic medications may contribute to obesity in ways that are only partly understood. Although successful obesity treatment is associated with clear health benefits and available treatments offer benefit to some, relapse remains the rule. CONCLUSIONS: Although the presence or development of obesity is a daunting problem, it should not be ignored by mental health professionals. Treatment should address not only obesity per se, but also its effects on self-esteem in a hostile cultural climate. Ongoing developments in basic and clinical research are likely to increase the range, efficacy, and acceptability of treatment options in the years ahead.

A prospective study of holiday weight gain.

BACKGROUND: It is commonly asserted that the average American gains 5 lb (2.3 kg) or more over the holiday period between Thanksgiving and New Year's Day, yet few data support this statement. METHODS: To estimate actual holiday-related weight variation, we measured body weight in a convenience sample of 195 adults. The subjects were weighed four times at intervals of six to eight weeks, so that weight change was determined for three periods: preholiday (from late September or early October to mid-November), holiday (from mid-November to early or mid-January), and postholiday (from early or mid-January to late February or early March). A final measurement of body weight was obtained in 165 subjects the following September or October. Data on other vital signs and self-reported health measures were obtained from the patients in order to mask the main outcome of interest. RESULTS: The mean (+/-SD) weight increased significantly during the holiday period (gain, 0.37+/-1.52 kg; P<0.001), but not during the preholiday period (gain, 0.18+/-1.49 kg; P=0.09) or the postholiday period (loss, 0.07+/-1.14 kg; P=0.36). As compared with their weight in late September or early October, the study subjects had an average net weight gain of 0.48+/-2.22 kg in late February or March (P=0.003). Between February or March and the next September or early October, there was no significant additional change in weight (gain, 0.21 kg+/-2.3 kg; P=0.13) for the 165 participants who returned for follow-up. CONCLUSIONS: The average holiday weight gain is less than commonly asserted. Since this gain is not reversed during the spring or summer months, the net 0.48-kg weight gain in the fall and winter probably contributes to the increase in body weight that frequently occurs during adulthood.

Report of a National Institutes of Health--Centers for Disease Control and Prevention workshop on the feasibility of conducting a randomized clinical trial to estimate the long-term health effects of intentional weight loss in obese persons.

A workshop was convened in 1997 by the National Institutes of Health and the Centers for Disease Control and Prevention to consider the need for and feasibility of conducting a randomized clinical trial to estimate the long-term health effects of intentional weight loss in obese persons. Although the benefits of weight loss in obese individuals may seem obvious, little information is available showing that intentional weight loss improves long-term health outcomes. Observational studies may be unable to provide convincing answers about the magnitude and direction of the health effects of intentional weight loss. Workshop participants agreed that a well-designed randomized clinical trial could answer several questions necessary for developing a rational clinical and public health policy for treating obesity. Such information will ultimately provide needed guidance on the risks and benefits of weight loss to health care providers and payers, as well as to millions of obese Americans.

Resting metabolic rate in African-American and Caucasian girls.

Recent studies have found a lower resting metabolic rate (RMR) in African-American (AA) women with obesity as compared with Caucasian (C) women with obesity. It is unknown if this difference in RMR is seen in prepubertal girls or in those of average body weight. Therefore, we studied RMR in 21 AA and 24 C girls, ages 7-10, who were well matched for age, weight, body mass index (BMI), and pubertal status. All had BMI between 15% and 85% for age and race, based on data from the First National Health and Nutrition Examination Survey. Fat free mass (FFM) was measured by dual-energy X-ray absorptiometry. RMR was measured with a Deltatrac indirect calorimeter under controlled conditions after the subjects underwent an overnight fast. The slopes of the regression equations were similar for both groups (p = 0.7). After adjustment for FEM, the AA girls had a significantly lower RMR than did the C girls (-92 +/- 32 kcal/d, p = 0.007 by analysis of covariance). This significance was maintained after exclusion of total body bone mineral content. These data suggest that normal-weight prepubertal AA girls may have reduced resting energy expenditure compared with C girls.

Differences in corticotropin-releasing hormone-stimulated adrenocorticotropin and cortisol before and after weight loss.

Little is known about the effects of intentional weight loss on the function of the hypothalamic-pituitary-adrenal (HPA) axis of obese individuals. We studied the HPA axis of 34 healthy obese women (body mass index, 40.2 +/- 7.9 kg/m2) before and after a 21.0 +/- 7.9-kg weight loss induced by a 26-week weight loss program that included 12 weeks of a 3350 kJ/day (800 Cal/day) liquid formula diet, 6 weeks of gradual refeeding, and 6 weeks of caloric stabilization at 5020-6280 kJ/day (1200-1500 Cal/day). Obese subjects were evaluated twice: before caloric restriction and during the last 3 weeks of caloric stabilization with a 3-h evening 1 microg/kg ovine CRH (oCRH) stimulation test. CRH-stimulated ACTH and cortisol values were compared to those of a control group of 12 normal weight women. Before caloric restriction, both ACTH and cortisol responses to oCRH were similar in obese women and normal weight controls. Weight loss did not significantly alter the ACTH response to oCRH; however, the total plasma cortisol response to oCRH decreased significantly with weight loss (area under the curve, 96,320 +/- 21,040 nmol/L x min before weight loss; 82,450 +/- 22,460 nmol/L x min after weight loss; P < 0.001). Cortisol-binding globulin also decreased significantly after weight loss (2,270 +/- 1,050 nmol/L) compared either to values obtained before weight loss (3,590 +/- 1,360 nmol/L; P < 0.001) or to those of normal weight controls (3,910 +/- 1,400 nmol/L; P < 0.001). Assay for plasma free cortisol, either before or 180 min after oCRH treatment, showed no significant changes in cortisol responses resulting from weight loss. As plasma free cortisol was not altered by weight reduction, the decrease in the total cortisol response to oCRH after weight loss appears to be secondary to significant decreases in cortisol-binding globulin. We conclude that when obese women lose large amounts of weight with a 3350 kJ/day, very low energy diet, such weight reduction does not significantly affect the HPA axis.