Showing papers in "Obesity in 2006"

The human obesity gene map: the 2005 update.

Abstract: This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

Confronting and Coping with Weight Stigma: An Investigation of Overweight and Obese Adults

Abstract: The total sample of 2671 overweight and obese adults were partitioned into two subsamples for investigation. Sample I was comprised of 2449 adult women, and Sample II was a matched sample of adult men and women (N = 222) that was disaggregated to investigate gender differences. Both samples completed an online battery of self-report questionnaires measuring frequency of weight stigmatization and coping responses to deal with bias, the most common sources of the bias, symptoms of depression, self-esteem, attitudes about weight and obesity, and binge eating behaviors .Experiences of weight stigmatization was common in both samples. A variety of coping strategies were used in response. More frequent exposure to stigma was related to more attempts to cope and higher BMI. Physicians and family members were the most frequent sources of weight bias reported. No gender differences were observed in types or frequency of stigmatization. Frequency of stigmatization was not related to current psychological functioning, although coping responses were associated with emotional well-being. These findings raise questions about the relationship between stigma and psychological functioning and have important implications for obesity treatment and stigma reduction intervention efforts, both of which are discussed.

Neurobiology of exercise.

Abstract: Voluntary physical activity and exercise training can favorably influence brain plasticity by facilitating neurogenerative, neuroadaptive, and neuroprotective processes. At least some of the processes are mediated by neurotrophic factors. Motor skill training and regular exercise enhance executive functions of cognition and some types of learning, including motor learning in the spinal cord. These adaptations in the central nervous system have implications for the prevention and treatment of obesity, cancer, depression, the decline in cognition associated with aging, and neurological disorders such as Parkinson's disease, Alzheimer's dementia, ischemic stroke, and head and spinal cord injury. Chronic voluntary physical activity also attenuates neural responses to stress in brain circuits responsible for regulating peripheral sympathetic activity, suggesting constraint on sympathetic responses to stress that could plausibly contribute to reductions in clinical disorders such as hypertension, heart failure, oxidative stress, and suppression of immunity. Mechanisms explaining these adaptations are not as yet known, but metabolic and neurochemical pathways among skeletal muscle, the spinal cord, and the brain offer plausible, testable mechanisms that might help explain effects of physical activity and exercise on the central nervous system.

The Look AHEAD study: a description of the lifestyle intervention and the evidence supporting it.

Abstract: The Look AHEAD (Action for Health in Diabetes) study is a multicenter, randomized controlled trial designed to determine whether intentional weight loss reduces cardiovascular morbidity and mortality in overweight individuals with type 2 diabetes. The study began in 2001 and is scheduled to conclude in 2012. A total of 5145 participants have been randomly assigned to a lifestyle intervention or to an enhanced usual care condition (i.e., diabetes support and education). This article describes the lifestyle intervention and the empirical evidence to support it. The two principal intervention goals are to induce a mean loss >or = 7% of initial weight and to increase participants' moderately intense physical activity to > or =175 min/wk. For the first 6 months, participants attend one individual and three group sessions per month and are encouraged to replace two meals and one snack a day with liquid shakes and meal bars. From months 7 to 12, they attend one individual and two group meetings per month and continue to replace one meal per day (which is recommended for the study's duration). Starting at month 7, more intensive behavioral interventions and weight loss medication are available from a toolbox, designed to help participants with limited weight loss. In Years 2 to 4, treatment is provided mainly on an individual basis and includes at least one on-site visit per month and a second contact by telephone, mail, or e-mail. After Year 4, participants are offered monthly individual visits. The intervention is delivered by a multidisciplinary team that includes medical staff who monitor participants at risk of hypoglycemic episodes.

Validation and Calibration of an Accelerometer in Preschool Children

Abstract: Objective: Obesity rates in young children are increasing, and decreased physical activity is likely to be a major contributor to this trend. Studies of physical activity in young children are limited by the lack of valid and acceptable measures. The purpose of this study was to calibrate and validate the ActiGraph accelerometer for use with 3- to 5-year-old children. Research Methods and Procedures: Thirty preschool children wore an ActiGraph accelerometer (ActiGraph, Fort Walton Beach, FL) and a Cosmed portable metabolic system (Cosmed, Rome, Italy) during a period of rest and while performing three structured physical activities in a laboratory setting. Expired respiratory gases were collected, and oxygen consumption was measured on a breath-by-breath basis. Accelerometer data were collected at 15-second intervals. For cross-validation, the same children wore the same instruments while participating in unstructured indoor and outdoor activities for 20 minutes each at their preschool. Results: In calibrating the accelerometer, the correlation between Vo2 (ml/kg per min) and counts was r = 0.82 across all activities. The only significant variable in the prediction equation was accelerometer counts (R2 = 0.90, standard error of the estimate = 4.70). In the cross-validation, the intraclass correlation coefficient between measured and predicted Vo2 was R = 0.57 and the Spearman correlation coefficient was R = 0.66 (p < 0.001). Cut-off points for moderate- and vigorous-intensity physical activity were identified at 420 counts/15 s (Vo2 = 20 mL/kg per min) and 842 counts/15 s (Vo2 = 30 mL/kg per min), respectively. When these cutpoints were applied to the cross-validation data, percentage agreement, kappa, and modified kappa for moderate activity were 0.69, 0.36, and 0.38, respectively. For vigorous activity, the same measures were 0.81, 0.13, and 0.62. Discussion: Accelerometer counts were highly correlated with Vo2 in young children. Accelerometers can be appropriately used as a measure of physical activity in this population.

Visceral fat is an independent predictor of all-cause mortality in men.

Abstract: Objective: To examine the independent associations of abdominal fat (visceral and subcutaneous) and liver fat with all-cause mortality. Research Methods and Procedures: Participants included 291 men [97 decedents and 194 controls; mean age, 56.4 ± 12.0 (SD) years] who received a computed tomography (CT) examination at the preventive medicine clinic in Dallas, TX, between 1995 and 1999, with a mean mortality follow-up of 2.2 ± 1.3 years. Abdominal fat was determined using contiguous CT images from the L3-L4 to L4-L5 intervertebral space. Liver fat was assessed using the CT-determined liver attenuation value, which is inversely related to liver fat. Logistic regression was used to determine the independent association between the fat depots and all-cause mortality. Results: During the study, there were 97 deaths. Visceral fat [odds ratio (OR) per SD: 1.83; 95% CI: 1.23 to 2.73], abdominal subcutaneous fat (1.44; 1.02 to 2.03), liver fat (0.64; 0.46 to 0.87), and waist circumference (1.41; 1.01 to 1.98) were significant individual predictors of mortality after controlling for age and length of follow-up. In a model including all three fat measures (subcutaneous, visceral, and liver fat), age, and length of follow-up, only visceral fat (1.93; 1.15 to 3.23) was a significant predictor of mortality. Discussion: Visceral fat is a strong, independent predictor of all-cause mortality in men.

Adipose tissue as an endocrine organ.

Abstract: Adipose tissue plays a critical role in energy homeostasis, not only in storing triglycerides, but also responding to nutrient, neural, and hormonal signals and secreting adipokines that control feeding, thermogenesis, immunity, and neuroendocrine function. A rise in leptin signals satiety to the brain through receptors in hypothalamic and brainstem neurons. Leptin activates tyrosine kinase, Janus kinase 2, and signal transducer and activator of transcription 3, leading to increased levels of anorexigenic peptides, e.g., alpha-melanocyte stimulating hormone and cocaine- and amphetamine-regulated transcript, and inhibition of orexigenic peptides, e.g., neuropeptide Y and agouti-related peptide. Obesity is characterized by hyperleptinemia and hypothalamic leptin resistance, partly caused by induction of suppressor of cytokine signaling-3. Leptin falls rapidly during fasting and potently stimulates appetite, reduces thermogenesis, and mediates the inhibition of thyroid and reproductive hormones and activation of the hypothalamic-pituitary-adrenal axis. These actions are integrated by the paraventicular hypothalamic nucleus. Leptin also decreases glucose and stimulates lipolysis through central and peripheral pathways involving AMP-activated protein kinase (AMPK). Adiponectin is secreted exclusively by adipocytes and has been linked to glucose, lipid, and cardiovascular regulation. Obesity, diabetes, and atherosclerosis have been associated with reduced adiponectin levels, whereas adiponectin treatment reverses these abnormalities partly through activation of AMPK in liver and muscle. Administration of adiponectin in the brain recapitulates the peripheral actions to increase fatty acid oxidation and insulin sensitivity and reduce glucose. Although putative adiponectin receptors are widespread in peripheral organs and brain, it is uncertain whether adiponectin acts exclusively through these targets. As with leptin, adiponectin requires the central melanocortin pathway. Furthermore, adiponectin stimulates fatty acid oxidation and reduces glucose and lipids, at least in part, by activating AMPK in muscle and liver.

The influence of one's own body weight on implicit and explicit anti-fat bias.

Abstract: SCHWARTZ, MARLENE B., LENNY R. VARTANIAN, BRIAN A. NOSEK, AND KELLY D. BROWNELL. The influence of one’s own body weight on implicit and explicit anti-fat bias. Obesity. 2006;14:440–447. Objective: This study examined the influence of one’s own body weight on the strength of implicit and explicit anti-fat bias. Research Methods and Procedure: Implicit and explicit anti-fat attitudes and obesity stereotypes were assessed among a large online sample (N 4283) that included representation from across the weight spectrum (from underweight to extremely obese). Respondents also indicated their willingness to make a range of personal sacrifices in exchange for not being obese. Results: All weight groups exhibited significant anti-fat bias, but there was an inverse relation between one’s own weight and the level of observed bias. Thinner people were more likely to automatically associate negative attributes (bad, lazy) with fat people, to prefer thin people to fat people, and to explicitly rate fat people as lazier and less motivated than thin people. However, when the lazy stereotype was contrasted with another negative attribute (anxious), obese and non-obese people exhibited equally strong implicit stereotyping. Finally, a substantial proportion of respondents indicated a willingness to endure aversive life events to avoid being obese. For example, 46% of the total sample indicated that they would rather give up 1 year of life than be obese, and 30% reported that they would rather be divorced than be obese. In each case, thinner people were more willing to sacrifice aspects of their health or life circumstances than were heavier people. Discussion: Although the strength of weight bias decreased as respondents’ body weight increased, a significant degree of anti-fat bias was still evident among even the most obese group of respondents, highlighting the pervasiveness of this bias.

Racial and Ethnic Differences in Secular Trends for Childhood BMI, Weight, and Height

Abstract: Objectives: The prevalence of childhood overweight in the United States has markedly increased over the last 30 years. We examined differences in the secular trends for BMI, weight, and height among white, black, and Mexican-American children. Research Methods and Procedures: Analyses were based on nationally representative data collected from 2 to 17 year olds in four examinations (1971–1974 through 1999–2002). Results: Overall, black children experienced much larger secular increases in BMI, weight, and height than did white children. For example, over the 30-year period, the prevalence of overweight increased ∼3-fold (4% to 13%) among 6- to 11-year-old white children but 5-fold (4% to 20%) among black children. In most sex-age groups, Mexican-American children experienced increases in BMI and overweight that were between those experienced by blacks and whites. Race/ethnicity differences were less marked among 2 to 5 year olds, and in this age group, white children experienced the largest increase in overweight (from 4% to 9%). In 1999–2002, the prevalence of extreme BMI levels (≥99th percentile) reached 6% to 7% among black girls and Mexican-American boys. Discussion: Because of the strong tracking of childhood BMI levels into adulthood, it is likely that the secular increases in childhood overweight will greatly increase the burden of adult disease. The further development of obesity interventions in different racial/ethnic groups should be emphasized.

Intramyocellular lipid content in human skeletal muscle

Abstract: Fat can be stored not only in adipose tissue but also in other tissues such as skeletal muscle. Fat droplets accumulated in skeletal muscle [intramyocellular lipids (IMCLs)] can be quantified by different methods, all with advantages and drawbacks. Here, we briefly review IMCL quantification methods that use biopsy specimens (biochemical quantification, electron microscopy, and histochemistry) and non-invasive alternatives (magnetic resonance spectroscopy, magnetic resonance imaging, and computed tomography). Regarding the physiological role, it has been suggested that IMCL serves as an intracellular source of energy during exercise. Indeed, IMCL content decreases during prolonged submaximal exercise, and analogously to glycogen, IMCL content is increased in the trained state. In addition, IMCL content is highest in oxidative, type 1 muscle fibers. Together, this, indeed, suggests that the IMCL content is increased in the trained state to optimally match fat oxidative capacity and that it serves as readily available fuel. However, elevation of plasma fatty acid levels or dietary fat content also increases IMCL content, suggesting that skeletal muscle also stores fat simply if the availability of fatty acids is high. Under these conditions, the uptake into skeletal muscle may have negative consequences on insulin sensitivity. Besides the evaluation of the various methods to quantify IMCLs, this perspective describes IMCLs as valuable energy stores during prolonged exercise, which, however, in the absence of regular physical activity and with overconsumption of fat, can have detrimental effects on muscular insulin sensitivity.

Why Visceral Fat is Bad: Mechanisms of the Metabolic Syndrome

Abstract: A consensus has emerged that fat stored in the central segment of the body is particularly damaging in that it portends greater risk for diabetes, cardiovascular disease, hypertension, and certain cancers (1–3). It is also accepted that insulin resistance is a related characteristic that may be an essential link between central fat and disease risk. Additionally, it is possible that the hyperinsulinemia that accompanies insulin resistance in non-diabetic but at-risk individuals may magnify, or even mediate, some of the detrimental effects of visceral adiposity (4–6). However, there is less information regarding the mechanisms that may link visceral fat with risk for disease. For example, there is controversy regarding the specific mechanisms by which fat in the visceral compartment confers greater risk than subcutaneous fat. Many investigators have suggested that one or more moieties secreted by the visceral adipocyte might mediate insulin resistance. Among the socalled “bad actors” are free fatty acids (FFAs) themselves (“portal theory”) (7–9) or the adipose tissue–released cytokines (adipokines) such as interleukin-1, interleukin-6, tumor necrosis factor, resistin, or a reduction in adiponectin, which has been repeatedly shown to be associated with reduced insulin resistance (10–13). Of course, insulin itself could be involved, as other adipose-secreted protein compounds not yet identified. But why visceral fat? Is it because of the unique anatomical position of the visceral fat depot, with effluent entering the liver, or is it because of molecular characteristics of visceral fat itself, which may favor release of damaging molecules into the systemic circulation? These questions remain unanswered. However, in our laboratory, we have developed the obese dog model, which has led to some understanding of the pathogenesis of the metabolic syndrome. The dog model has not been widely used for the study of the metabolic syndrome, but we have found it to have several important characteristics that we have been able to exploit: the ability to make longitudinal measurements and the ability to access the portal vein. In that sense the dog is a unique model, in that these latter measurements are daunting in rodents, and carrying out repetitive, invasive clinical measurements in non-human primates is challenging. Also, the dog with visceral obesity has turned out to be a reasonable model for a similar syndrome in humans (Figure 1). In fact, the dog is genetically more similar to humans than is the rodent. Here we summarize a significant amount of evidence in which we examined what we considered to be the simplest hypothesis composed of two postulates: 1) that FFAs per se are among the most important products of the visceral adipocyte to cause insulin resistance (and hence the metabolic syndrome) and 2) that the anatomical position of the visceral adipose depot (i.e., portal drainage into the liver) plays an important role in the pathogenesis of the metabolic syndrome. While we cannot say that these postulates are proven, there are data that support them, and Occam’s razor instructs us to accept them until proven untrue. Whether true or not, it appears that examining them has led us to a deeper understanding of the physiological basis for the metabolic syndrome itself. One similarity between dogs and humans is the wide variance in fat deposition in a “wild” or “natural” population. We measure distribution of fat about the truncal region using magnetic resonance imaging [Figure 2; 11 axial slices: 1-cm landmark slice at the umbilicus (left renal artery) 5 cm]. Similar to human subjects (14,15), there is surprising variability in distribution. Some animals are strikingly lean, with total fat varying over a factor of 5, from 10 to 50 cm/cm non-fat tissue. Interestingly, there is a tendency for visceral adiposity to increase rapidly as one examines animals with increasing body fat; the visceral fat depot tends to plateau, and subcutaneous fat increases more rapidly with overall obesity. This tendency for visceral fat to Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California. Address correspondence to Richard N. Bergman, Department of Physiology and Biophysics, MMR 630, 1333 San Pablo Street, Los Angeles CA 90033. E-mail: rbergman@usc.edu Copyright © 2006 NAASO

The Evolution of Very-Low-Calorie Diets: An Update and Meta-analysis

Abstract: Objective: Very-low-calorie diets (VLCDs), providing <800 kcal/d, have been used since the 1970s to induce rapid weight loss. Previous reviews of the literature have disagreed concerning the relative efficacy of VLCDs vs. conventional low-calorie diets (LCDs) for achieving long-term weight loss. Research Methods and Procedures: We sought to update findings on the clinical use, safety, and efficacy of VLCDs and to perform a meta-analysis of randomized trials that compared the long-term efficacy of LCDs and VLCDs. Original research articles were retrieved by a Medline search and from prior reviews of VLCDs. Trials were included only if they were randomized comparisons of LCDs and VLCDs and included a follow-up assessment at least 1 year after maximum weight loss. Data were abstracted by both authors regarding: duration of VLCD, total length of treatment, attrition, short- and long-term weight loss, changes in weight-related comorbidities, and adverse effects. Results: Six randomized trials were found that met inclusion criteria. VLCDs, compared with LCDs, induced significantly greater short-term weight losses (16.1 ± 1.6% vs. 9.7 ± 2.4% of initial weight, respectively; p = 0.0001) but similar long-term losses (6.3 ± 3.2% vs. 5.0 ± 4.0%, respectively; p > 0.2). Attrition was similar with VLCD and LCD regimens. Discussion: VLCDs did not produce greater long-term weight losses than LCDs. In the United States, the use of liquid meal replacements as part of a 1000 to 1500 kcal/d diet may provide an effective and less expensive alternative to VLCDs. In Europe, VLCDs are used with less intensive medical supervision than in the United States, which reduces the cost of this approach.

Bioelectrical Impedance Underestimates Total and Truncal Fatness in Abdominally Obese Women

Abstract: OBJECTIVE: To compare estimates of total and truncal fatness from eight-electrode bioelectrical impedance analysis equipment (BIA(8)) with those from DXA in centrally obese women. The secondary aim ...

Predictors of health-related quality of life in obese youth.

Abstract: ZELLER, MEG H. AND AVANI C. MODI. Predictors of health-related quality of life in obese youth. Obesity. 2006; 14:122-130. Objective: Recent literature has documented the psychosocial consequences of pediatric obesity, including poor health-related quality of life (HRQOL). The present study examines HRQOL and its association with depressive symptoms and perceived social support in African-American and white youth pursuing weight management treatment. Research Methods and Procedures: Study participants were 166 obese youth (mean = 12.7 years, 70% females, 57% African American, mean BMI = 37.0) referred to a pediatric weight management program. Parents of participants completed a demographics form and the parent-proxy Pediatric Quality of Life Inventory (PedsQL). Youth completed the Children's Depression Inventory, PedsQL, and Perceived Social Support Scale for Children. Results: HRQOL scores were quite impaired relative to published norms on healthy youth (p < 0.001). Approximately 11 % of the sample met criteria for clinically significant depressive symptoms. Simultaneous regression analyses revealed that depressive symptoms, perceived social support from classmates, degree of overweight, and socioeconomic status seem to be strong predictors of HRQOL. Discussion: Obesity has a clear impact on HRQOL regardless of respondent (e.g., parent, youth) or racial group. It is likely that assessing and treating depressive symptoms and fostering social support in the context of pediatric intervention have implications for both improved HRQOL and weight management outcomes.

Leptin resistance and obesity

Abstract: The prevalence of obesity, and the human and economic costs of the disease, creates a need for better therapeutics and better understanding of the physiological processes that balance energy intake and energy expenditure. Leptin is the primary signal from energy stores and exerts negative feedback effects on energy intake. In common obesity, leptin loses the ability to inhibit energy intake and increase energy expenditure; this is termed leptin resistance. This review discusses the evidence in support of leptin resistance in mouse models and humans and the possible mechanisms of leptin resistance.

Relation of BMI and physical activity to sex hormones in postmenopausal women.

Abstract: Objective: Levels of estrogen, androgen, and prolactin have been related to risk of postmenopausal breast cancer However, the determinants of these hormone concentrations are not established The purpose of this study was to examine correlates of endogenous sex hormones Research Methods and Procedures: Associations among adiposity, physical activity, and diet and concentrations of estradiol, free estradiol, estrone, testosterone, free testosterone, sex hormone-binding globulin (SHBG), androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and prolactin were evaluated in 267 postmenopausal women randomly selected from the Women's Health Initiative Dietary Modification Trial Results: In multiple regression analyses on log-transformed hormones, BMI was positively associated with estrone (β = 0031, p < 0001), estradiol (β = 0048, p < 0001), free estradiol (β = 0062, p < 0001), free testosterone (β = 0017, p = 002), and prolactin (β = 0012, p = 002) and negatively associated with SHBG (β = −002, p = 0001) Total physical activity (metabolic equivalent tasks per week) was negatively associated with concentrations of estrone, estradiol, and androstenedione (β = −0006, −0007, and −0005, respectively, all p ≤ 005) Using a composite variable of BMI and physical activity dichotomized by median values, women with high BMI/low physical activity had a mean estrone concentration of 288 pg/mL, compared with 241, 199, and 184 pg/mL for women with high BMI/high physical activity, low BMI/low physical activity, and low BMI/high physical activity, respectively (p trend < 0001) Similar trends were observed for estradiol and free estradiol and, in inverse, for SHBG Discussion: These associations may, in part, explain the positive associations between overweight/obesity and a sedentary lifestyle on breast cancer risk

Effects of resistant starch, a non-digestible fermentable fiber, on reducing body fat.

Abstract: Objective: To assess the effects of energy dilution with non-fermentable and fermentable fibers on abdominal fat and gut peptide YY (PYY) and glucagon-like peptide (GLP)-1 expressions, three rat studies were conducted to: determine the effects of energy dilution with a non-fermentable fiber, compare similar fiber levels of fermentable and non-fermentable fibers, and compare similar metabolizable energy dilutions with fermentable and non-fermentable fibers. Research Methods and Procedures: In Study 1, rats were fed one of three diets with different metabolizable energy densities. In Study 2, rats were fed diets with similar fiber levels using high amylose-resistant cornstarch (RS) or methylcellulose. In Study 3, rats were fed diets with a similar dilution of metabolizable energy using cellulose or RS. Measurements included food intake, body weight, abdominal fat, plasma PYY and GLP-1, gastrointestinal tract weights, and gene transcription of PYY and proglucagon. Results: Energy dilution resulted in decreased abdominal fat in all studies. In Study 2, rats fed fermentable RS had increased cecal weights and plasma PYY and GLP-1, and increased gene transcription of PYY and proglucagon. In Study 3, RS-fed rats had increased short-chain fatty acids in cecal contents, plasma PYY (GLP-1 not measured), and gene transcription for PYY and proglucagon. Discussion: Inclusion of RS in the diet may affect energy balance through its effect as a fiber or a stimulator of PYY and GLP-1 expression. Increasing gut hormone signaling with a bioactive functional food such as RS may be an effective natural approach to the treatment of obesity.

Homeostatic and non-homeostatic pathways involved in the control of food intake and energy balance.

Abstract: A neural network sensitive to leptin and other energy status signals stretching from the hypothalamus to the caudal medulla has been identified as the homeostatic control system for the regulation of food intake and energy balance. While this system is remarkably powerful in defending the lower limits of adiposity, it is weak in curbing appetite in a world of plenty. Another extensive neural system that processes appetitive and rewarding aspects of food intake is mainly interacting with the external world. This non-homeostatic system is constantly attacked by sophisticated signals from the environment, ultimately resulting in increased energy intake in many genetically predisposed individuals. Recent findings suggest a role for accumbens-hypothalamic pathways in the interaction between non-homeostatic and homeostatic factors that control food intake. Identification of the neural pathways that mediate this dominance of cortico-limbic processes over the homeostatic regulatory circuits in the hypothalamus and brainstem will be important for the development of behavioral strategies and pharmacological therapies in the fight against obesity.

Differential effects of gastric bypass and banding on circulating gut hormone and leptin levels.

Abstract: Objective: To quantify plasma concentrations of hormones that regulate energy homeostasis in order to establish possible mechanisms for greater weight loss after Roux-en-Y gastric bypass (RYGBP) compared with gastric banding (BND). Research Methods and Procedures: Four groups of women were studied: lean (n = 8; mean BMI, 21.6 kg/m2); BND (n = 9; BMI, 35.8; 25% weight loss), RYGBP (n = 9; BMI, 34.2; 36% weight loss), and controls matched for BMI to the surgical groups (n = 11; BMI, 34.4). Results: Fasting total peptide YY (PYY) and PYY(3–36) immunoreactivity were similar among all groups, but the postprandial response in the RYGBP group was exaggerated, such that 30 minutes after the meal, total and PYY(3–36) levels were 2- to 4-fold greater compared with all other groups. Maximal postprandial suppression of total ghrelin was blunted in the BND group (13%) compared with RYGBP (27%). Postprandial suppression of octanoylated ghrelin was also less in BND (29%) compared with RYGBP (56%). Fasting insulin was lower in RYGBP (6.6 μU/mL) compared with BND (10.0 μU/mL). Compared with lean controls, leptin concentrations were significantly higher in BND but not in RYGBP. There was a greater increase in post-meal satiety in the RYGBP group compared with BND and overweight controls. Discussion: The differences between RYGBP and BND subjects in postprandial concentrations of PYY and ghrelin would be expected to promote increased satiety and earlier meal termination in RYGBP and may aid in greater weight loss. The differences in insulin and leptin concentrations associated with these procedures may also reflect differences in insulin sensitivity and energy partitioning.

Influence of parents' eating behaviors and child feeding practices on children's weight status.

Abstract: JOHANNSEN, DARCY L., NEIL M. JOHANNSEN, AND BONNY L. SPECKER. Influence of parents’ eating behaviors and child feeding practices on children’s weight status. Obesity. 2006;14:431–439. Objective: To investigate the effects of mothers’ and fathers’ eating behaviors, child feeding practices, and BMI on percentage body fat and BMI in their children. Research Methods and Procedures: Four hundred fiftyeight parents (239 mothers, 219 fathers) were asked to complete two questionnaires: the Three-Factor Eating Questionnaire and the Child Feeding Questionnaire, which measure dimensions of parent eating behavior and child feeding practices, respectively. Parent BMI was calculated from self-reported height and weight; children’s measures included BMI and percentage fat assessed by DXA. Regression analyses were used to analyze relationships between parents’ BMI and questionnaire scores and children’s weight status. Results: One hundred forty-three mothers and 68 fathers returned questionnaires, representing parents of 148 children 3 to 5 years old (78 boys). Children’s weight was related to mothers’ BMI, but not fathers’. Girls had a greater BMI if either parent reported being overweight as a child, and both girls and boys were likely to be overweight if their mothers believed they had risky eating habits (fussiness, eating too much, etc.). Girls with fathers who were more controlling had a higher percentage fat; these fathers were also more concerned about their daughters’ future health. Discussion: Mothers exert a strong influence over their children’s weight and seem to be more concerned about their children’s eating behaviors; however, fathers play a role in imposing child feeding practices. Gender bias may be present in child feeding, as suggested by dissimilar effects of parent practices on the weight status of girls vs. boys. Fathers should be included in future studies analyzing parent feeding practices and children’s weight outcome.

Waist circumference correlates with metabolic syndrome indicators better than percentage fat.

Abstract: Objective: Percent fat is often considered the reference for establishing the magnitude of adipose tissue accumulation and the risk of excess adiposity. However, the increasing recognition of a strong link between central adiposity and metabolic disturbances led us to test whether waist circumference (WC) is more highly correlated with metabolic syndrome components than percent fat and other related anthropometric measures such as BMI. Research Methods and Procedures: BMI, WC, and percent fat, measured by DXA, were evaluated in 1010 healthy white and African-American men and women [age, 48.3 ± 17.2 (standard deviation) years; BMI, 27.0 ± 5.3 kg/m2]. The associations of BMI, WC, and percent fat with age and laboratory-adjusted health risk indicators (i.e., serum glucose, insulin, triglycerides, high-density lipoprotein cholesterol, blood pressure) in each sex and ethnicity group were examined. Results: For 18 of 24 comparisons, the age- and laboratory-adjusted correlations were lowest for percent fat and in 16 of 24 comparisons were highest for WC. Fifteen of the between-method differences reached statistical significance. With health risk indicator as the dependent variable and anthropometric measures as the independent variable, the contribution of percent fat to the WC regression model was not statistically significant; in contrast, adding WC to the percent fat regression model did make a significant independent contribution for most health risk indicators. Discussion: WC had the strongest associations with health risk indicators, followed by BMI. Although percent fat is a useful measure of overall adiposity, health risks are best represented by the simply measured WC.

Body image and quality of life in post massive weight loss body contouring patients.

Abstract: Objective: Because post-bariatric surgery patients undergo massive weight loss, the resulting skin excess can lead to both functional problems and profound dissatisfaction with appearance. Correcting skin excess could improve all these corollaries, including body image. Presently, few data are available documenting body image and weight-related quality of life in this population. Research Methods and Procedures: Eighteen patients who underwent both bariatric surgery and body contouring completed our study. Both established surveys and new surveys designed specifically for the study were used to assess body perception and ideals, quality of life, and mood. Patients were surveyed at the following time-points: pre-body contouring (after massive weight loss) and both 3 and 6 month post-body contouring. Statistical testing was performed using Student's t test and ANOVA. Results: The mean age of the patients was 46 ± 10 years (standard deviation). Quality of life improved after obesity surgery and was significantly enhanced after body contouring. Three months after body contouring, subjects ascribed thinner silhouettes to both current appearance and ideal body image. Body image also improved with body contouring surgery. Mood remained stable over 6 months. Discussion: Body contouring after surgical weight loss improved both quality-of-life measurements and body image. Initial body dissatisfaction did not correlate with mood. Body contouring improved body image but produced dissatisfaction with other parts of the body, suggesting that as patients become closer to their ideal, these ideals may shift. We further developed several new assessment methods that may prove useful in understanding these post-surgical weight loss patients.

A physiological role of breast milk leptin in body weight control in developing infants.

Abstract: MIRALLES, OLGA, JUANA SANCHEZ, ANDREU PALOU, AND CATALINA PICO ´ . A physiological role of breast milk leptin in body weight control in developing infants. Obesity. 2006;14:1371-1377. Objective: Leptin, a hormone that regulates food intake and energy metabolism, is present in breast milk. The aim of this study was to determine whether milk leptin concentration is correlated with maternal circulating leptin and BMI and with body weight gain of infants. Research Methods and Procedures: A group of 28 non- obese women (BMI between 16.3 and 27.3 kg/m 2 ) who breast-fed their infants for at least 6 months and their infants were studied. Venous blood and milk samples were ob- tained from mothers at 1, 3, 6, and 9 months of lactation, and leptin concentration was determined. Infant body weight and height were followed until 2 years of age. Results: During the whole lactation period, milk leptin concentration correlated positively with maternal plasma leptin concentration and with maternal BMI. In addition, milk leptin concentration at 1 month of lactation was neg- atively correlated with infant BMI at 18 and 24 months of age. A better negative correlation was also found between log milk leptin concentration at 1 and at 3 months of lactation and infant BMI from 12 to 24 months of age. Discussion: We concluded that, in a group of non-obese mothers, infant body weight during the first 2 years may be influenced by milk leptin concentration during the first stages of lactation. Thus, moderate milk-borne maternal leptin appears to provide moderate protection to infants from an excess of weight gain. These results seem to point out that milk leptin is an important factor that could explain, at least partially, the major risk of obesity of formula-fed infants with respect to breast-fed infants.

Intensive Weight Loss Program Improves Physical Function in Older Obese Adults with Knee Osteoarthritis

Abstract: Results: Body weight decreased 8.7 0.8% in WL and 0.0 0.7% in WS. Body fat and fat-free mass were lower for WL than WS at 6 months (estimated means: fat 38.1 0.4% vs. 40.9 0.4%, respectively; fat-free mass 56.7 0.4 vs. 58.8 0.4 kg, respectively). WL had better function than WS, with lower Western Ontario and McMaster University Osteoarthritis Index scores, greater 6-minute walk distance, and faster stair climb time (p 0.05). Changes in function were associated with weight loss in the entire cohort. Discussion: An intensive weight loss intervention incorporating energy deficit diet and exercise training improves physical function in older obese adults with knee OA. Greater improvements in function were observed in those with the most weight loss.

Weight gain induced by high-fat feeding involves increased liver oxidative stress.

Abstract: MILAGRO, FERMIN I., JAVIER CAMPION, AND J. ALFREDO MARTINEZ. Weight gain induced by high-fat feeding involves increased liver oxidative stress. Obesity. 2006;14:1118 -1123. Objective: To assess the effects of high-fat feeding on white adipose tissue gene expression and liver oxidative stress. Research Methods and Procedures: Male Wistar rats were fed on standard pelleted or high-fat diet to produce a diet- induced obesity model. Therefore, body composition, serum biochemical values and liver malondialdehyde (MDA) were determined after 56 days of feeding. Expression (mRNA) values of three genes were also determined by reverse transcriptase-polymerase chain reaction in white adipose tissue. Results: Animals fed on the high-fat diet showed more body weight, higher fat deposition and total liver weight, and increased energy intake compared with those on the stan- dard-fat diet. Serum fasting measurements (glucose, insulin, leptin) and homeostasis model assessment insulin resistance index were significantly increased by the high-fat diet con- sumption. As an indicator of oxidative stress, peroxide decomposition in liver was analyzed, showing an increase of MDA concentrations in rats fed on high-fat diet in comparison with control rats. Interestingly, liver MDA lev- els correlated positively with body weight gain, serum lep- tin, and homeostasis model assessment. Finally, leptin and glycerol-3-phosphate dehydrogenase mRNA levels, but not fatty acid synthase, were increased by high-fat diet in com- parison with the control-fed group. Discussion: These results show a link among increased fat depots, insulin resistance, and liver oxidative stress. Thus, liver oxidative stress probably contributes to hepatic disor- ders and aggravates the metabolic syndrome, which is ac- companied by a stimulation of the esterification of fatty acids as measured by glycerol-3-phosphate dehydrogenase in the adipose tissue, providing support to the hypothesis that not only calories count in the induction of weight gain or metabolic syndrome and that other factors such as oxi- dative stress may be involved.

Hip-Hop to Health Jr. for Latino Preschool Children

Abstract: Objective: Hip-Hop to Health Jr. was a diet/physical activity intervention designed to reduce gains in BMI (kilograms per meter squared) in preschool minority children. Research Methods and Procedures: Twelve predominantly Latino Head Start centers participated in a group-randomized trial conducted between Fall 2001 and Winter 2003. Six centers were randomized to a culturally proficient 14-week (three times weekly) diet/physical activity intervention. Parents participated by completing weekly homework assignments. The children in the other six centers received a general health intervention that did not address either diet or physical activity. The primary outcome was change in BMI, and secondary outcomes were changes in dietary intake and physical activity. Measures were collected at baseline, post-intervention, and at Years 1 and 2 follow-up. Results: There were no significant differences between intervention and control schools in either primary or secondary outcomes at post-intervention, Year 1, or Year 2 follow-ups. Discussion: When Hip-Hop to Health Jr. was conducted in predominantly black Head Start centers, it was effective in reducing subsequent increases in BMI in preschool children. In contrast, when the program was conducted in Latino centers, it was not effective. Although the intervention did not prevent excessive weight gain in Latino children, it was very well received. Future interventions with this population may require further cultural tailoring and a more robust parent intervention.

Comparison of Body Composition Methods in Obese African‐American Women

Abstract: Objective: To compare the accuracy of percentage body fat (%BF) estimates between bioelectrical impedance analysis (BIA) and DXA in obese African-American women. Research Methods and Procedures: Fifty-five obese African-American women (mean age, 45 years; mean BMI, 38; mean %BF, 48%) were studied. BF was assessed by both BIA (RJL Systems BIA 101Q; RJL Systems, Clinton Township, MI) and DXA (Hologic QDR-2000 Bone Densitometer; Hologic Inc., Bedford, MA). Generalized and ethnicity- and obese-specific equations were used to calculate %BF from the BIA. Bland-Altman analyses were used to compare the agreement between the BIA and the DXA, with the DXA serving as the criterion measure. Results: Two of the generalized equations provided consistent estimates across the weight range in comparison with the DXA estimates, whereas most of the other equations increasingly underestimated %BF as BF increased. One of the generalized and one of the ethnicity-specific equations had mean differences that were not significantly different from the DXA value. Discussion: The findings show that the Lukaski equation provided the most precise and accurate estimates of %BF in comparison with the QDR 2000 and provide preliminary support for the use of this equation for obese African-American women.

Influence of metabolic syndrome on biomarkers of oxidative stress and inflammation in obese adults.

Abstract: Objective: Both obesity and the metabolic syndrome (MetS) have been independently linked with increased oxidative and inflammatory stress. This study tested the hypothesis that obesity with MetS is associated with greater oxidative and inflammatory burden compared with obesity alone. Research Methods and Procedures: Forty-eight normal-weight and 40 obese (20 without MetS; 20 with MetS) adults were studied. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria. Plasma concentrations of oxidized low-density lipoprotein, C-reactive protein, tumor necrosis factor-α, interleukin (IL)-6, and IL-18 were determined by enzyme immunoassay. Results: Plasma biomarkers of oxidative stress and inflammation were lowest in normal-weight controls. Of note, obese MetS adults demonstrated significantly higher plasma concentrations of oxidized low-density lipoprotein (62.3 ± 3.2 vs. 54.0 ± 4.0 U/L; p < 0.05), C-reactive protein (3.0 ± 0.6 vs. 1.5 ± 0.3 mg/L; p < 0.01), tumor necrosis factor-α (2.1 ± 0.1 vs. 1.6 ± 0.1 pg/mL; p < 0.05), IL-6 (2.8 ± 0.4 vs. 1.4 ± 0.2 pg/mL; p < 0.01), and IL-18 (253 ± 16 vs. 199 ± 16 pg/mL; p < 0.01), compared with obese adults without MetS. Discussion: These results suggest that MetS heightens oxidative stress and inflammatory burden in obese adults. Increased oxidative and inflammatory stress may contribute to the greater risk of coronary heart disease and cerebrovascular disease in obese adults with MetS.

Obesity and sexual quality of life.

Abstract: KOLOTKIN, RONETTE L., MARTIN BINKS, ROSS D. CROSBY, TRULS OSTBYE, RICHARD E. GRESS, AND TED D. ADAMS. Obesity and sexual quality of life. Obesity. 2006;14:472–479. Objectives: Reduced sexual quality of life is a frequently reported yet rarely studied consequence of obesity. The objectives of this study were to 1) examine the prevalence of sexual quality-of-life difficulties in obese individuals and 2) investigate the association between sexual quality of life and BMI class, sex, and obesity treatment–seeking status. Research Methods and Procedures: Subjects consisted of 1) 500 participants in an intensive residential program for weight loss and lifestyle modification (BMI 41.3 kg/m 2 ), 2) 372 patients evaluated for gastric bypass surgery (BMI 47.1 kg/m 2 ), and 3) 286 obese control subjects not seeking weight loss treatment (BMI 43.6 kg/m 2 ). Participants completed the Impact of Weight on Quality of Life-Lite, a measure of weight-related quality of life. Responses to the four Sexual Life items (assessing enjoyment, desire, performance, and avoidance) were analyzed by BMI, sex, and group. Results: Higher BMI was associated with greater impairments in sexual quality of life. Obese women reported more impairment in sexual quality of life than obese men for three of four items. Gastric bypass surgery candidates reported more impairment in sexual quality of life than residential patients and controls for most items. In general, residential patients reported levels of impairment greater than or equal to controls. Discussion: Obesity is associated with lack of enjoyment of sexual activity, lack of sexual desire, difficulties with sexual performance, and avoidance of sexual encounters. Sexual quality of life is most impaired for women, individuals with Class III obesity, and patients seeking gastric bypass surgery.

Active transportation to school over 2 years in relation to weight status and physical activity.

Abstract: OBJECTIVE: To prospectively examine potential benefits of active commuting to school on measures of weight status and physical activity in a sample of youth. Research Methods and Procedures: A cohort of students from seven elementary schools was measured four times--in the fall and spring of fourth grade (N = 1083) and fifth grade (N = 924). Participants were classified as active (walking, biking, or skateboarding to school almost every day for baseline analyses or at least 2 d/wk for analyses of consistent active commuting) or non-active commuters to school. Accelerometers were used to measure physical activity. Height, weight, and skinfolds were objectively assessed. RESULTS: Boys who actively commuted to school had lower BMI (p DISCUSSION: Walking and cycling to school may contribute to preventing excessive weight gain, or leaner children may walk or cycle to school. KW: SR2S Language: en