Associations of the melanocortin 3 receptor C17A + G241A haplotype with body composition and inflammation in African-American adults.

BACKGROUND: The MC3R haplotype C17A + G241A, which encodes a partially inactivated receptor, has high prevalence in individuals of predominately African ancestry. In pediatric cohorts, homozygosity for this common variant has been associated with obesity, reduced lean mass, and greater fasting insulin. However, metabolic and body composition measures have not been well studied in adults with this haplotype. METHODS: A convenience sample of 237 healthy African-American adult volunteers was studied. TaqMan assays were used to genotype MC3R variants. Labs were drawn in the morning in the fasted state. Body composition data was obtained via dual-energy X-ray absorptiometry. An analysis of covariance was used to examine the associations of genotype with metabolic and body composition measures controlling for age and sex. RESULTS: Individuals homozygous for the MC3R C17A + G241A haplotype had significantly greater body mass index, fat mass, fat mass percentage, and C-reactive protein, with reduced lean mass percentage as compared to heterozygous and wild-type participants (all ps < 0.05); fasting insulin was marginally nonsignificant between groups (p = 0.053). After adjusting for fat mass, laboratory differences no longer remained significant. CONCLUSIONS: Homozygosity for MC3R C17A + G241A is associated with increased adiposity in African-American adults. Further studies are needed to elucidate the mechanisms behind these associations.

Pediatric Loss-of-Control Eating and Anxiety in Relation to Components of Metabolic Syndrome.

Objective: Pediatric loss-of-control (LOC) eating is associated with, and predictive of, gains in adiposity and adverse metabolic outcomes. In addition, some preliminary data suggest that anxiety may exacerbate the relationship of LOC eating with weight and metabolic syndrome (MetS)-related measures. We therefore examined whether anxiety moderated the relationship between LOC eating and body mass index z (BMIz), adiposity, and MetS-related measures in youth. Methods: A convenience sample of non-treatment-seeking boys and girls of varying weight strata were interviewed to determine the presence of LOC eating and completed a questionnaire assessing trait anxiety. BMIz and MetS-related measures (blood pressure, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, and insulin) were measured after an overnight fast. Adiposity was assessed by air displacement plethysmography or dual-energy x-ray absorptiometry. Analyses adjusted for age, sex, race, height, fat mass, and depressive symptoms, as appropriate. Results: In all, 379 youths (13.0 ± 2.8 years; 53% female; BMIz = 0.8 ± 1.1; 22% with LOC eating) were studied. Anxiety was not significantly related to BMIz, adiposity, or MetS-related measures. However, anxiety and LOC eating interacted such that only among youth with LOC eating, anxiety was positively associated with fasting insulin (p = .02) and insulin resistance (p = .01). The interaction of anxiety and LOC eating was not significantly related to BMIz, adiposity, or any other MetS-related measure (ps = ns). Conclusions: Only among non-treatment-seeking youth with LOC eating, anxiety may be associated with increased insulin secretion and insulin resistance. Longitudinal studies are required to confirm these findings and explore mechanisms for these relationships.

Cross-Sectional and Longitudinal Examination of Insulin Sensitivity and Secretion across Puberty among Non-Hispanic Black and White Children.

BACKGROUND: Few studies using criterion measures of insulin sensitivity (SI) and insulin secretory capacity (ISC) have been conducted across puberty to adulthood. We examined how SI and ISC change from pre-puberty through adulthood. METHODS: Hyperglycemic clamp studies were performed in a convenience sample of non-Hispanic Black (NHB) and White children evaluated at age 6 to 12 years and at approximately 5-year intervals into adulthood (maximum age 27 years). SI and ISC (first-phase and steady-state insulin secretion) were determined cross-sectionally in 133 unique participants across puberty and in adulthood. Additionally, longitudinal changes in SI and ISC were compared at two timepoints among three groups defined by changes in pubertal development: pre-pubertal at baseline and late-pubertal at follow-up (n=27), early-pubertal at baseline and late-pubertal at follow-up (n=27), and late-pubertal at baseline and adult at follow-up (n=24). RESULTS: Cross-sectionally, SI was highest in pre-puberty and early puberty and lowest in mid-puberty (analysis of covariance [ANCOVA] P=0.001). Longitudinally, SI decreased from pre-puberty to late puberty (P<0.001), then increased somewhat from late puberty to adulthood. Cross-sectionally, first-phase and steady-state ISC increased during puberty and decreased in adulthood (ANCOVA P<0.02). Longitudinally, steady-state and first-phase ISC increased from pre-puberty to late puberty (P<0.007), and steady-state ISC decreased from late puberty to adulthood. The NHB group had lower SI (P=0.003) and greater first-phase and steady-state ISC (P≤0.001), independent of pubertal development. CONCLUSION: This study confirms that SI decreases and ISC increases transiently during puberty and shows that these changes largely resolve in adulthood.

Weight-based teasing is associated with gain in BMI and fat mass among children and adolescents at-risk for obesity: A longitudinal study.

BACKGROUND: Youths with overweight and obesity report frequent instances of weight-based teasing. However, little is known about the prospective associations between weight-based teasing and changes in body composition among youth. OBJECTIVE: To assess associations between weight-based teasing and changes in body mass index (BMI) and fat mass in a longitudinal study of youths with, or at-risk for, overweight and obesity. METHODS: One hundred ten youths with, or at-risk for, overweight participated in a longitudinal observational study. The Perception of Teasing Scale was administered at baseline. Height, weight, and body composition were obtained at baseline and at follow-ups (range: 1-15 years). RESULTS: Mean age at baseline was 11.8 years; 53% had overweight/obesity; 36% were non-Hispanic Black; 55% were female; mean follow-up from baseline: 8.5 years. Adjusting for covariates and repeated measures of BMI or fat mass, linear mixed models revealed that weight-based teasing was associated with greater gain of BMI and fat mass across the follow-up period (ps ≤ .007). Adjusting for covariates, youths reporting high weight-based teasing (two standard deviations above the mean) experienced a 33% greater gain in BMI (an additional 0.20 kg/m2 ) and a 91% greater gain in fat mass (an additional 0.65 kg) per year compared with peers who reported no weight-based teasing. CONCLUSIONS: Among youths with, and at-risk for, overweight and obesity, weight-based teasing was associated with greater weight and fat gain.

Associations of Weekday and Weekend Sleep with Children's Reported Eating in the Absence of Hunger.

Insufficient average sleep duration has been inconsistently associated with poor diet and obesity risks in youth. Inconsistencies in findings across studies may be due to a general failure to examine associations in weekday versus weekend sleep. We hypothesized that greater variations in weekday and weekend sleep duration would be associated with more disinhibited eating behaviors, which, in turn, might be involved in the relationship between sleep and weight. We, therefore, examined, among healthy, non-treatment seeking youth, the associations of average weekly, weekend, and weekday sleep duration with eating in the absence of hunger (EAH), a disinhibited eating behavior associated with disordered eating and obesity. Sleep was assessed via actigraphy for 14 days. Participants completed a self-report measure of EAH. Adiposity was measured by dual-energy X-ray absorptiometry. Linear regressions were used to test the associations of sleep duration with EAH and the associations of sleep duration and EAH, with fat mass. Among 123 participants (8-17 years, 52.0% female, and 30.9% with overweight), there was no significant association between average weekly sleep and EAH. Further, there was no significant association among average weekly sleep duration or EAH and fat mass. However, average weekday sleep was negatively associated, and average weekend sleep was positively associated, with EAH (ps < 0.02). Weekend "catch-up" sleep (the difference between weekend and weekday sleep) was positively associated with EAH (p < 0.01). Findings indicate that shorter weekday sleep and greater weekend "catch-up" sleep are associated with EAH, which may place youth at risk for the development of excess weight gain over time.

Associations of sleep patterns with metabolic syndrome indices, body composition, and energy intake in children and adolescents.

BACKGROUND: Self-reported short sleep duration is associated with greater risk for metabolic syndrome (MetS), obesity, and higher energy intake (EI). However, studies of these associations in children using objective methods are sparse. OBJECTIVES: The study aims to determine the associations for sleep patterns with MetS indices, body composition, and EI using objective measures in children. METHODS: Free-living sleep and physical activity were measured in 125 children (aged 8-17 years, BMI z = 0.57 ± 1.0, 55% female) using wrist-worn actigraphs for 14 nights. Blood pressure, fasting blood levels of lipids, insulin, glucose, waist circumference, and body composition (dual-energy X-ray absorptiometry [DXA]) were obtained during outpatient visits. EI was assessed during an ad libitum buffet meal. RESULTS: Later weekday and weekend bedtimes were associated with higher systolic blood pressure (Ps < 0.05). Sleep duration and bedtime were not significantly associated with other components of MetS, body composition, or EI. Short sleepers (duration less than 7 hours) consumed a greater percentage of carbohydrates than those with adequate (greater than or equal to 7 hours) sleep (P < 0.05). CONCLUSION: Indicators of sleep duration were variably associated with children's eating patterns and risk for chronic disease. Prospective data are needed to determine whether these indicators of sleep quality represent unique or shared risk factors for poor health outcomes.

An examination of the associations between pediatric loss of control eating, anxiety, and body composition in children and adolescents.

BACKGROUND: Data on the link between anxiety and body composition in youth are mixed. Yet, anxiety and disordered eating are highly correlated. One pathway between anxiety and excess body weight and fat mass may be through loss of control (LOC) eating. We examined whether LOC eating mediated the relationship between anxiety and body composition in youth with and without overweight. METHOD: Non-treatment-seeking youth (8-17 years) participated in studies examining weight and eating behaviors. Anxiety (child- and parent-report of child) and LOC eating were assessed by self-report questionnaires and interviews, respectively. Fat mass was assessed by dual-energy x-ray absorptiometry or air displacement plethysmography. Cross-sectional mediation models with bias-corrected bootstrap confidence intervals (CI) were conducted. RESULTS: 257 youth (12.91 ±â€¯2.76 years; 52.5% female; BMI-z 0.93 ±â€¯1.07) were studied. There was a significant indirect path between child-reported anxiety and both BMI-z (ab = .005, SE = 0.003, 95% CI = 0.001-0.01) and body fat mass (ab = 0.001, SE = 0.001, 95% CI ≤0.001-0.003) through the number of LOC episodes in the past month. No significant indirect paths through the number of LOC episodes was observed for parent-report of child anxiety on BMI-z (ab = 0.004, SE = 0.01, 95% CI = -0.01-0.03) or body fat mass (ab = 0.001, SE = 0.002, 95% CI = -0.002-0.01). No direct paths were observed between anxiety and body composition regardless of the informant. DISCUSSION: LOC eating appears to mediate the relationship of child-reported anxiety with body composition in non-treatment seeking boys and girls. Prospective data are needed to determine if anxiety promotes LOC eating that results in increased risk for excess body weight and fat gain.