Changes in circulating satiety hormones in obese children: a randomized controlled physical activity-based intervention study

Effects of multidisciplinary therapy on energy balance, inflammation, and metabolic diseases in adolescents with obesity: A narrative review

Obesity is a consequence of multiple factors, including genetics, lifestyle and nutritional choices, physical activity, sleep duration, screen time, and mood disorders. These behavioral elements can impair the regulation of energy balance and obesity management that link obesity to a constellation of chronic conditions that lead to a high prevalence of cardiometabolic risk factors, metabolic syndrome, and nonalcoholic fatty liver disease. Multidisciplinary therapy is defined as an approach delivered by a multidisciplinary-trained health team covering at least two components of behavior, physical activity/exercise, dietary habits, and/or psychological counseling associated with clinical interventions. This narrative review summarizes the effects of multidisciplinary therapy on neuroendocrine regulation of energy balance, inflammatory biomarkers, cardiometabolic risk factors, metabolic syndrome, nonalcoholic fatty liver diseases, behavior, and quality of life. We found that multidisciplinary therapy, including medical, nutritional, exercise, and behavioral counseling, and/or education, was useful for addressing outcomes such as visceral adiposity, neuroendocrine regulation of energy balance, inflammatory biomarkers, cardiometabolic risk factors, nonalcoholic fatty liver disease, and metabolic syndrome. The effects were mediated by improvements in neuroendocrine regulation of energy balance, downregulation of the pro-inflammatory states, and a reduction in comorbidities. Multidisciplinary therapy also improved mood disorders and quality of life.

Sex differences in response to lifestyle intervention among children and adolescents: Systematic review and meta-analysis

OBJECTIVE

Little is known about sex differences in response to lifestyle interventions among pediatric populations. The purpose of this analysis was to evaluate sex differences in adiposity following lifestyle interventions among children and adolescents with overweight or obesity aged 6 to 18 years old.

METHODS

Searches were conducted in PubMed, Web of Science, and MEDLINE (from inception to March 2021), and references from included articles were examined. Eligibility criteria included children and adolescents aged 6 to 18 years with overweight or obesity, randomization to a lifestyle intervention versus a control group, and assessment of at least one adiposity measure. Corresponding authors were contacted to obtain summary statistics by sex (n = 14/49).

RESULTS

Of 89 full-text articles reviewed, 49 (55%) were included, of which 33 (67%) reported statistically significant intervention effects on adiposity. Only two studies (4%) evaluated sex differences in response to lifestyle intervention, reporting conflicting results. The results of the meta-regression models demonstrated no significant differences in the treatment effect between male and female youth for weight (beta = -0.05, SE = 0.18, z = -0.28, p = 0.8), BMI (beta = 0.03, SE = 0.14, z = 0.19, p = 0.85), BMI z score (beta = -0.04, SE = 0.18, z = -0.23, p = 0.82), percentage body fat (beta = -0.11, SE = 0.16, z = -0.67, p = 0.51), and waist circumference (beta = -0.30, SE = 0.25, z = -1.18, p = 0.24).

CONCLUSIONS

The meta-analysis revealed that youth with overweight or obesity do not demonstrate a differential response to lifestyle intervention in relation to adiposity-related outcomes.

[Metabolic profile and concentration of ghrelin and obestatin in children and adolescents with obesity]

Background

It has been pointed out that ghrelin and obestatin could have an impact on the genesis of obesity, since they estimulate and inhibit apetite and, therefore, food consumption.

Objective

To compare the metabolic profile, lipid profile and the concentrations of ghrelin and obestatin in children with normal weight or obesity.

Material and methods

Cross-sectional design with 97 normal weight or obese children, 6 to 18 years of age, who did not present systemic diseases. The serum concentrations of glucose, insulin, total cholesterol, triglycerides, high (HDL), low (LDL) and very low density (VLDL) lipoproteins, aspartate aminotransferase (AST), alanine aminotransferase (ALT), ghrelin and obestatin were determined. Descriptive statistics were performed. Student's t test was used to compare groups, and correlation coefficients of ghrelin and obestatin values with biochemical and anthropometric variables. A p value of ≤ 0.05 was significant.

Results

55 children with normal weight and 42 with obesity were included; mean age was 10.7 years. Triglycerides, LDL, VLDL, ALT and insulin were higher, and HDL lower in obese children (p < 0.05). Ghrelin values were higher in normal weight children (p < 0.05), and there was no difference in obestatin values.

Conclusions

The lower concentration of ghrelin in obese children may indicate a negative feedback to regulate energy consumption. Children and adolescents with obesity show metabolic and lipid profile alterations that place them at risk of early development of cardiovascular risk factors.

Effects of low-glycemic index diet on plasma adipokines in obese children

BACKGROUND

A low-glycemic index (GI) diet may modulate adipocyte-produced adipokines linking to insulin resistance.

METHODS

The stored plasma samples from the RCT of a low-GI vs. conventional diet in obese children were analyzed for adipokines: leptin, adiponectin, resistin, and visfatin. Their relationships with clinical outcomes were assessed.

RESULTS

Fifty-two participants completed the 6-month intervention trial (mean age: 12.0 ± 2.0 years, 35 boys). Both groups had significantly decreased BMI z-scores from baseline whereas the low-GI group had significant reduction in fasting insulin and HOMA-IR. There were no differences in adipokines between the groups before and after the intervention. However, there was an association between baseline leptin and the change of fat mass index (FMI) but not the insulin resistance in both groups. The higher the baseline leptin was, the lower the changes were for FMI after the intervention.

CONCLUSION

Despite no demonstrable effect of low-GI diet on plasma adipokines, the higher baseline leptin was correlated with lower reduction of fat mass. Leptin resistance may have a detrimental effect on the reduction of adiposity in obese children. Baseline leptin could be a useful predictor of the change in body composition in an obesity intervention trial.

IMPACT

Leptin resistance may have a detrimental effect in reducing the adiposity in obese children. This study is the first of its kind to compare the plasma adipokine concentrations of obese children on low-GI diet and conventional diet. We found that serum leptin was significantly correlated with the reduction of BMI z-score and FMI in both groups. Baseline leptin could be a useful predictor of the change in body composition in an obesity intervention trial.

Branched-chain Amino Acids and Relationship With Inflammation in Youth With Obesity: A Randomized Controlled Intervention Study

CONTEXT

Elevated concentrations of branched-chain amino acids (BCAA) are strong predictors of type 2 diabetes mellitus (T2DM). Their association with cardiovascular disease (CVD) remains uncertain, particularly in youth.

OBJECTIVE

We investigated the role of BCAA and aromatic amino acids (AAA) in obesity, their relationships with novel biomarkers of CVD, and response to a physical activity-based lifestyle intervention (PAL-I) in a randomized controlled study in youth with normal weight (NW) and obesity (OB).

METHODS

Age (14-18 years) and Tanner stage (≥IV) matched youth (OB, n = 15 and NW, n = 6) were studied; the 15 participants with OB underwent a 3-month randomized controlled PAL-I. Circulating amino acid profile, glucose, insulin, lipids, adiponectin, retinol binding protein-4, fibrinogen, high-sensitivity C-reactive protein, interleukin-6, and 25-hydroxy vitamin-D, along with body composition, were measured at baseline and after PAL-I. Independent t tests, analysis of covariance, and mixed-effect models were used for analysis of the data.

RESULTS

Compared with NW, the concentration of various amino acids, including BCAA and AAA, were altered in OB (P < 0.05). BCAA and AAA showed baseline correlations with body composition and novel biomarkers of CVD, particularly inflammatory factors (all P < 0.05). The PAL-I produced only negligible effects (P > 0.05) on BCAA and AAA. Glutamine, glycine, and aspartic acid decreased with PAL-I (all P < 0.05).

CONCLUSION

The novel finding of the BCAA-inflammation relationship, along with strong correlations with nontraditional biomarkers of CVD, may raise the prospect of BCAA as a biomarker of CVD and evoke a potential link between obesity, T2DM, and CVD.

The impacts of exercise on pediatric obesity

Over the last few decades, the rates of pediatric obesity have more than doubled regardless of sociodemographic categorization, and despite these rates plateauing in recent years there continues to be an increase in the severity of obesity in children and adolescents. This review will discuss the pediatric obesity mediated cardiovascular disease (CVD) risk factors such as attenuated levels of satiety and energy metabolism hormones, insulin resistance, vascular endothelial dysfunction, and arterial stiffness. Additionally, early intervention to combat pediatric obesity is critical as obesity has been suggested to track into adulthood, and these obese children and adolescents are at an increased risk of early mortality. Current suggested strategies to combat pediatric obesity are modifying diet, limiting sedentary behavior, and increasing physical activity. The effects of exercise intervention on metabolic hormones such as leptin and adiponectin, insulin sensitivity/resistance, and body fat in obese children and adolescents will be discussed along with the exercise modality, intensity, and duration. Specifically, this review will focus on the differential effects of aerobic exercise, resistance training, and combined exercise on the cardiovascular risks in pediatric obesity. This review outlines the evidence that exercise intervention is a beneficial therapeutic strategy to reduce the risk factors for CVD and the ideal exercise prescription to combat pediatric obesity should contain both muscle strengthening and aerobic components with an emphasis on fat mass reduction and long-term adherence.

Risk factors and predictive biomarkers of early cardiovascular disease in obese youth

Obesity in childhood and adolescence continues to be a major health issue due to significant health implications and to the economic burden that arise from treating this disease and its complications. Current data show that childhood obesity is no longer just a concern for developed countries, but more significantly affecting developing countries. In adult population, cardiovascular disease is the main cause of mortality and morbidity among obese patients. It is therefore believed that risk factors found in adult patients could also be observed in obese youth. These risk factors will then persist and become progressively worse if obese youth remain obese as they reach adulthood. However, risk reduction is achievable through various prevention and management strategies of obesity and obese children who become nonobese in adulthood have a significant reduction in their risk of developing cardiovascular disease. New biomarkers to improve risk assessment in obese youth are an open research field, which will eventually lead to a more targeted approach in prevention and treatment. Nevertheless, there is still a need for continuous research in understanding the roles of these biomarkers and their potential in risk prediction. Cardiovascular risk modification of childhood obesity depends on a more concerted effort among the various parties involved and particularly a global collaboration to stop the rising prevalence of the epidemic in developing countries.

Does Physical Activity-Based Intervention Improve Systemic Proinflammatory Cytokine Levels in Overweight or Obese Children and Adolescents? Insights from a Meta-Analysis of Randomized Control Trials

OBJECTIVES

The purpose of this research was to conduct a meta-analysis of the role that physical activity (PA) plays in influencing the critical proinflammatory cytokine levels associated with overweight/obese children and adolescents to explore the effectiveness of exercise intervention within this population.

METHODS

With searches of the PubMed, EMBASE, and CENTRAL databases, we updated our meta-analysis up to November 2018. The randomized controlled trials (RCT) evaluated the ability of exercise training to increase the following factors in children and/or adolescents classified as obese or overweight: tumor necrosis factor (TNF)-α, interleukin (IL)-6, and C-reactive protein (CRP).

RESULTS

Eleven RCT comprising 623 children and/or adolescents who were obese or overweight (i.e., 393 with PA and 230 controls) were suitable for use in this study. The meta-analysis showed that PA in general was associated with a significant reduction of CRP levels (mean difference = -0.45 mg/L, p = 0.02) in overweight/obese children and adolescents. Based on 115 overweight and obese youths, this study suggests that PA does not significantly mitigate IL-6 levels (mean difference = -0.39 pg/mL, p = 0.08), although there was a trend towards a reduction. Additionally, no close connection was observed between PA and TNF-α levels at 0.04 pg/mL (p = 0.78). Moreover, meta-regression analysis revealed a statistical association between CPR levels and changes in BMI or changes in adiponectin; likewise, IL-6 levels dramatically impacted the effect of exercise on changes in adiponectin.

CONCLUSIONS

PA was associated with significantly reduced CRP levels, whereas there was no significant association with IL-6 or TNF-α in overweight/obese children or adolescents; however, there was a trend towards a reduction of IL-6.

Relationship of circulating spexin with markers of cardiovascular disease: a pilot study in adolescents with obesity

PURPOSE

Spexin, a novel peptide, has potential implications in obesity, satiety and energy homeostasis. The current study examined the relationship of spexin with various biomarkers of cardiovascular disease and endothelial function in adolescents with obesity.

METHODS

Nineteen adolescents with obesity (age, 15.8 ± 1.7 years) were studied. Spexin, leptin and various cardiovascular disease biomarkers were measured. Endothelial function was assessed by high-resolution Doppler ultrasonography of the right brachial artery.

RESULTS

Spexin concentration (median [interquartile range] 0.38 ng/mL [0.29-0.59 ng/mL]) was inversely correlated (r = -0.50, P = 0.03) with leptin. When participants were clustered into two groups ('high spexin and low leptin' vs. 'low spexin and high leptin'), the odds of having 'low spexin and high leptin' in participants with higher hs-CRP (≥ 3 mg/L) were 12.25 times (95 per cent CI -1 to139, P = 0.026) higher than those of participants with lower hs-CRP (<3 mg/L). Spexin levels, however, were not associated with measures of endothelial function.

CONCLUSIONS

The inverse association between spexin and leptin and the presence of higher concentrations of hs-CRP in adolescents with obesity in the setting of 'low spexin and high leptin' suggest a potential role for spexin in the regulation of satiety and certain cardiovascular risk factors in children with obesity.

Effect of Low- Versus High-Intensity Exercise Training on Biomarkers of Inflammation and Endothelial Dysfunction in Adolescents With Obesity: A 6-Month Randomized Exercise Intervention Study

PURPOSE

To investigate the effects of a low- versus high-intensity aerobic training on biomarkers of inflammation and endothelial dysfunction in adolescents with obesity.

METHODS

Sixty-two adolescents with obesity [age = 15 (14) y, body mass index = 34.87 (4.22) kg·m^-2] were randomized to receive either a high-intensity training (HIT, n = 31) or a low-intensity training (LIT, n = 31) for 24 weeks. All participants also received nutritional, psychological, and clinical counseling. Leptin, total and subtype leukocyte counts, tumor necrosis factor-alpha, interleukin-6, myeloperoxidase, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were obtained at baseline and after 24 weeks.

RESULTS

HIT reduced neutrophils [from 4.4 (1.9) to 3.6 (1.3) µL^-1 × 10³; P = .01] and monocytes [from 7.2 (2.5) to 5.2 (1.8) µL^-1 × 10²; P < .01], but LIT increased neutrophils [from 4.5 (1.7) to 5.2 (3.3) µL^-1 × 10³; P = .01]. Although tumor necrosis factor-alpha increased in LIT [from 13.3 (7.5) to 17.7 (10.8) pg·mL^-1; P = .01], it decreased in HIT [from 12.4 (7.5) to 11.3 (6.2) pg·mL^-1; P = .01]. No changes in leukocyte counts, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and homeostasis assessment model for insulin resistance were observed.

CONCLUSIONS

Both HIT and LIT improved the inflammatory profile. The study, however, indicated that the number of biomarkers and the magnitude of changes were higher in the HIT compared with LIT.

Searching for Evidence of an Anti-Inflammatory Diet in Children: A Systematic Review of Randomized Controlled Trials for Pediatric Obesity Interventions With a Focus on Leptin, Ghrelin, and Adiponectin

PROBLEM

To address the complex phenomenon of pediatric obesity, one must understand the physiological mechanisms regulating energy intake and inflammation. The peptide hormones leptin, ghrelin, and adiponectin are involved in both, but their functions are dysregulated in obesity. The purpose of this systematic review is (1) to characterize studies of nutrition interventions for weight management in children who measure these peptides as outcomes, (2) to assess risk of bias in the studies, and (3) to determine the relationships between these peptides and body mass index (BMI). Eligibility Criteria: Peer-reviewed articles written in English, published in 2001-2016, and describing randomized controlled trials of pediatric interventions involving a nutrition component with the outcome measures leptin, ghrelin, and/or adiponectin were included. Articles were excluded if the intervention involved pharmaceuticals, supplements, infant formula, breastfeeding, or surgery.

SAMPLE

The 25 international studies represented 2,153 obese children.

RESULTS

Ten diets were identified. Successful interventions included both structured exercise and hypocaloric dietary components, with or without counseling, resistance training, or medical components. Direct measures of adiposity were used in 69% of studies. Comparison group designs were disparate. Leptin levels decreased as BMI decreased. Evidence regarding the relationships of ghrelin and adiponectin with BMI was inconclusive.

CONCLUSIONS

Despite known effects of maturation on hormones, studies did not consistently differentiate findings by maturational stage. Common anti-inflammatory and disease risk modification diets were missing or underrepresented. Studies that include children with comorbidities are needed. BMI and leptin levels have a positive relationship, but evidence on ghrelin and adiponectin was inconclusive.

Exercise, adipokines and pediatric obesity: a meta-analysis of randomized controlled trials

BACKGROUND/OBJECTIVE

Adipokines are involved in the etiology of diabetes, insulin resistance, and the development of atherosclerosis and other latent-onset complications. The objective of this meta-analysis was to determine the effectiveness of exercise interventions on adipokines in pediatric obesity.

SUBJECTS/METHODS

A computerized search was made using three databases. The analysis was restricted to studies that examined the effect of exercise interventions on adipokines (adiponectin, leptin, resistin and visfatin) in pediatric obesity (6-18 years old). Fourteen randomized controlled trials (347 youths) were included. Weighted mean difference (WMD) and 95% confidence intervals were calculated.

RESULTS

Exercise was associated with a significant increase in adiponectin (WMD=0.882 μg ml-1, 95% CI, 0.271-1.493) but did not alter leptin and resistin level. Likewise, exercise intensity and change in body fat; as well as total exercise program duration, duration of the sessions, and change in body fat all significantly influenced the effect of exercise on adiponectin and leptin, respectively.

CONCLUSIONS

Exercise seems to increase adiponectin levels in childhood obesity. Our results also suggested that exercise on its own, without the concomitant presence of changes in body composition levels, does not affect leptin levels.

Metformin increases hepatic leptin receptor and decreases steatosis in mice

In addition to the ascertained efficacy as antidiabetic drug, metformin is increasingly being used as weight-loss agent in obesity, and as insulin sensitizer in nonalcoholic fatty liver disease (NAFLD). However, the mechanisms underlying these effects are still incompletely understood. Emerging evidence suggest metformin as leptin sensitizer to mediate the weight-loss effect in the brain. In this study, we investigated effects of metformin on expression of leptin receptors in liver and kidney in mice. C57BL/6 mice were fed with chow diet (CD) or high-fat diet (HF) for 5months. Afterward, mice were treated with metformin (50mg/kg or 200mg/kg) for 15days. Metabolic parameters and hepatic gene expression were analyzed at the end of the treatment. We also tested the effects of metformin on plasma-soluble leptin receptor (sOB-R) levels in newly diagnosed type 2 diabetes mellitus (T2DM) patients, and assessed its effect on hepatosteatosis in mice. Results showed that metformin upregulates the expression of leptin receptors (OB-Ra, -Rb, -Rc, and -Rd) in liver but not kidney. The stimulation effect is dose-dependent in both chow and HF mice. Upregulation of OB-Rb, long signaling isoform, needs a relatively higher dose of metformin. This effect was paralleled by increased sOBR levels in mice and T2DM patients, and decreased hepatic triglyceride (TG) content and lipogenic gene expression, including sterol regulatory element-binding protein 1c (SREBP-1c), fatty acid synthase (FAS) and acetyl-CoA carboxylase-1 (ACC-1). Taken together, these data identify hepatic leptin receptor as target gene being upregulated by metformin which may enhance leptin sensitivity in liver to alleviate steatosis.

EFFECT OF PHYSICAL ACTIVITY ON CARDIOMETABOLIC MARKERS IN ADOLESCENTS: SYSTEMATIC REVIEW

ABSTRACT The accumulation of body fat is a major risk factor for cardiometabolic diseases. Obesity can be considered a chronic systemic inflammatory disease in adults and younger people. The control of subclinical inflammation process through the practice of physical activity (PA) can mitigate the effects of risk factors that trigger atherosclerosis that worsens with advancing age. The objective of this study was to conduct a systematic review of the influence of physical activity and/or exercise on cardiometabolic markers and othrer risk factors of cardiovascular disease in adolescents. A systematic review was conducted in electronic databases Scopus, Pubmed, Conchrane Collection and SciELO. The terms used in the search were "cardiovascular diseases AND inflammation AND adolescents AND physical activity OR exercise". A total of 24 original articles were evaluated, being 14 longitudinal and 10 cross-sectional studies. Overall, 16 articles (66.66%) showed that PA, exercise and/or sedentary behavior may have influenced or have been related to the concentration of cardiometabolic markers. All studies that examined lifestyle changes showed reduction of cardiometabolic markers. Some limitations were observed: reduced samples, lack of dietary prescription, evaluation and control of volume and intensity of exercise. Most of the studies analyzed showed that the physical activity could influence and decrease the concentrations of cardiometabolic markers in adolescents. However, studies with representative sample size and precise control in assessing the level of physical activity and/or exercise are required to determine accurately the changes that the more active lifestyle can bring on inflammatory process, as well as other risk factors for cardiometabolic diseases in adolescents.

Effects of a multi-component camp-based intervention on inflammatory markers and adipokines in children: A randomized controlled trial

OBJECTIVE

To examine the effects of a multi-component camp-based intervention on inflammatory markers and adipokines in children.

METHODS

One hundred and fifteen children were recruited in Odense, Denmark (2012-2014). The participants were randomly allocated to either the day camp intervention arm (DCIA) or the standard intervention arm (SIA). The intervention for the DCIA consisted of a 6-week camp-based intervention and a 46-week family-based intervention. The SIA was offered one weekly physical activity session for 6 weeks and one educational meeting. C-reactive protein (CRP), monocyte chemoattractant protein-1 (MCP1), leptin, and adiponectin were measured in serum at baseline, 6 weeks and 52 weeks.

RESULTS

In comparison with the SIA, the reductions in CRP (P=0.003) and leptin (p<0.001) were larger in the DCIA at 6 weeks. The intervention effects on leptin were significantly mediated by the changes in body fat mass. No intervention effects on CRP and leptin were seen at 52 weeks. No between-group differences in changes in MCP1 and adiponectin were observed at 6 weeks or 52 weeks.

CONCLUSIONS

The 6-week camp intervention resulted in reductions in CRP and leptin. The intervention effects did not persist to 52 weeks. The intervention effect on leptin was explained by changes in body fat mass.

Ghrelin, adipokines, metabolic factors in relation with weight status in school-children and results of a 1-year lifestyle intervention program

BACKGROUND

Overweight in Guadeloupe is a public health matter affecting children and adults. In the present study we evaluated the metabolic profile, including serum ghrelin, leptin and adiponectin levels, in normal weight, overweight and obese school children and we analyzed the potential changes in anthropometric and metabolic risk factors after a 1-year lifestyle intervention program.

METHODS

Parameters were assessed at baseline and at 1 year. Three groups (G) were defined according the International Obesity Task Force reference values, G1: normal weight / G2: overweight / G3: obese. The lifestyle intervention included dietary counseling, regular physical activity and family support.

RESULTS

A total of 120 children (G1: n = 44, G2: n = 39, G3: n = 37), aged 11- 15 years and 59 % girls were enrolled. Obese children showed significant lower HDL-C, adiponectin and ghrelin concentrations, higher triglycerides, fasting blood glucose, insulin and leptin levels and also higher frequencies of abdominal obesity (G1: 2.3 %, G2: 28.2 %, G3: 73 %) and insulin resistance (GI: 39 %, G2: 72 %, G3: 89 %) than the other groups. In the overall sample, the linear regressions exploring the associations of ghrelin, adiponectin and leptin with age, gender, BMI z-score, HOMA-IR and tanner stage as independent variables showed strong associations of leptin levels with weight status and insulin resistance at baseline. The models accounted for 58 % of variability in leptin levels compared with 26 and 15 % for adiponectin and ghrelin levels respectively. In 83 children who completed the program, significant decreases in BMI z-score in overweight and obese children were noted. Leptin levels decreased significantly only in the obese group whereas adiponectin concentrations increased significantly in the three groups, In obese children, a significant correlation was found between changes in BMI Z-score, and changes in leptin levels (r = 0.39; P = 0.049) but not with changes in adiponectin levels.

CONCLUSIONS

Abdominal obesity and insulin resistance were highly prevalent in obese children highlighting their risk of metabolic complications in adulthood. A 1-year long lifestyle intervention was associated with improvement in BMI z-score and metabolic parameters.

Fasting gut hormone levels change with modest weight loss in obese adolescents

BACKGROUND

Gut hormones change with weight loss in adults but are not well studied in obese youth.

OBJECTIVE

The primary aim was to evaluate how gut hormones and subjective appetite measure change with dietary weight loss in obese adolescents.

METHODS

Participants were a subset of those taking part in the 'Eat Smart Study'. They were aged 10-17 years with body mass index (BMI) > 90th centile and were randomized to one of three groups: wait-listed control, structured reduced carbohydrate or structured low-fat dietary intervention for 12 weeks. Outcomes were fasting glucose, insulin, leptin, adiponectin, total amylin, acylated ghrelin, active glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP) and total peptide tyrosine-tyrosine. Pre- and postprandial subjective sensations of appetite were assessed using visual analogue scales.

RESULTS

Of 87 'Eat Smart' participants, 74 participated in this sub-study. The mean (standard deviation) BMI z-score was 2.1 (0.4) in the intervention groups at week 12 compared with 2.2 (0.4) in the control group. Fasting insulin (P = 0.05) and leptin (P = 0.03) levels decreased, while adiponectin levels increased (P = 0.05) in the intervention groups compared with control. The intervention groups were not significantly different from each other. A decrease in BMI z-score at week 12 was associated with decreased fasting insulin (P < 0.001), homeostatic model of assessment-insulin resistance (P < 0.001), leptin (P < 0.001), total amylin (P = 0.03), GIP (P = 0.01), PP (P = 0.02) and increased adiponectin (P < 0.001). There was no significant difference in appetite sensations.

CONCLUSIONS

Modest weight loss in obese adolescents leads to changes in some adipokines and gut hormones that may favour weight regain.

Appetite-related peptides in childhood and adolescence: role of ghrelin, PYY, and GLP-1

During childhood and adolescence, a number of factors, including age, puberty, sex, race, and body composition, may contribute to differences in satiety, food intake, and appetite-related peptides. These peptides include the orexigenic peptide ghrelin and anorexigenic gut peptides peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). For example, lower fasting ghrelin levels, lower postprandial ghrelin suppression, and blunted PYY and GLP-1 responses to food intake could contribute to a dysregulation of appetite in already obese children and adolescents. Whereas, changes in these peptides observed during puberty could facilitate growth. A greater understanding of the major moderating factors of appetite-related peptides in the pediatric population is essential to improve interpretation of study findings and for effective tailoring of strategies targeting appetite control to individuals. While more studies are needed, there is some evidence to suggest that exercise-based lifestyle interventions could be a potential therapeutic strategy to improve appetite-peptide profiles in overweight and obese children and adolescents. The aim of this review is (i) to discuss the potential moderating factors of ghrelin, PYY, and GLP-1, including age and puberty, sex, race and body composition; and (ii) to examine the effects of exercise interventions on these appetite-related gut peptides in children and adolescents.

Blunted suppression of acyl-ghrelin in response to fructose ingestion in obese adolescents: the role of insulin resistance

OBJECTIVE

Fructose consumption has risen alongside obesity and diabetes. Gut hormones involved in hunger and satiety (ghrelin and PYY) may respond differently to fructose compared with glucose ingestion. This study evaluated the effects of glucose and fructose ingestion on ghrelin and PYY in lean and obese adolescents with differing insulin sensitivity.

METHODS

Adolescents were divided into lean (n = 14), obese insulin sensitive (n = 12) (OIS), and obese insulin resistant (n = 15) (OIR). In a double-blind, cross-over design, subjects drank 75 g of glucose or fructose in random order, serum was obtained every 10 minutes for 60 minutes.

RESULTS

Baseline acyl-ghrelin was highest in lean and lowest in OIR (P = 0.02). After glucose ingestion, acyl-ghrelin decreased similarly in lean and OIS but was lower in OIR (vs. lean, P = 0.03). Suppression differences were more pronounced after fructose (lean vs. OIS, P = 0.008, lean vs. OIR, P < 0.001). OIS became significantly hungrier after fructose (P = 0.015). PYY was not significantly different at baseline, varied minimally after glucose, and rose after fructose.

CONCLUSIONS

Compared with lean, OIS adolescents have impaired acyl-ghrelin responses to fructose but not glucose, whereas OIR adolescents have blunted responses to both. Diminished suppression of acyl-ghrelin in childhood obesity, particularly if accompanied by insulin resistance, may promote hunger and overeating.

Changes in ghrelin and asymmetrical dimethylarginine in obese Mexican adolescents after six-month lifestyle intervention

The aim of this study was to evaluate the effect of a six-month lifestyle intervention on ghrelin and asymmetrical dimethylarginine (ADMA) in obese Mexican adolescents. A total of 65 obese Mexican adolescents aged 10-16 years completed a six-month lifestyle intervention. Anthropometric and biochemical parameters were assessed at baseline and at six months. Twenty normal-weight adolescents were also evaluated at baseline. Insulin resistance (IR) was determined by the homeostasis model assessment of IR (HOMA-IR). Ghrelin and ADMA were determined by enzyme-linked immunosorbent assay. Obese adolescents presented significantly higher triglycerides, cholesterol, glucose, insulin, HOMA-IR, and ADMA levels, while ghrelin was significantly lower. The lifestyle intervention led to a significant improvement in HOMA-IR, ghrelin, and ADMA in the whole studied obese subjects. ADMA and ghrelin levels were associated with BMI and IR components. According to the value of HOMA-IR, the obese subjects were divided into subjects with or without IR, no difference in ghrelin and ADMA was observed in these two subgroups. After intervention, the obese with IR showed increased ghrelin and decreased ADMA, while the obese without IR only showed improvement in ghrelin. The multiple linear regression analysis revealed that the changes of systolic blood pressure were the only predictor for the changes of ghrelin in the obese with IR. Our study demonstrated the increase of ADMA and the decrease of ghrelin in obese adolescents. Lifestyle intervention improved insulin resistance, decreased ADMA, and increased ghrelin in obese subjects with IR although no significant weight loss was observed.

Effect of exercise on appetite-regulating hormones in overweight women

Over the past decade, our knowledge of how homeostatic systems regulate food intake and body weight has increased with the discovery of circulating peptides such as leptin, acyl ghrelin, des-acyl ghrelin and obestatin. These hormones regulate the appetite and food intake by sending signals to the brain regarding the body's nutritional status. The purpose of this study was to investigate the response of appetite-regulating hormones to exercise. Nine overweight women undertook two 2 h trials in a randomized crossover design. In the exercise trial, subjects ran for 60 min at 50% of maximal oxygen uptake followed by a 60 min rest period. In the control trial, subjects rested for 2 h. Obestatin, acyl ghrelin, des-acyl ghrelin and leptin concentrations were measured at baseline and at 20, 40, 60, 90 and 120 min after baseline. A two-way ANOVA revealed a significant (P < 0.05) interaction effect for leptin and acyl ghrelin. However, changes in obestatin and des-acyl ghrelin concentration were statistically insignificant (P > 0.05). The data indicated that although acute treadmill exercise resulted in a significant change in acyl ghrelin and leptin levels, it had no effect on plasma obestatin and des-acyl ghrelin levels.

Pediatric non alcoholic fatty liver disease: old and new concepts on development, progression, metabolic insight and potential treatment targets

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. NAFLD has emerged to be extremely prevalent, and predicted by obesity and male gender. It is defined by hepatic fat infiltration >5% hepatocytes, in the absence of other causes of liver pathology. It includes a spectrum of disease ranging from intrahepatic fat accumulation (steatosis) to various degrees of necrotic inflammation and fibrosis (non-alcoholic steatohepatatis [NASH]). NAFLD is associated, in children as in adults, with severe metabolic impairments, determining an increased risk of developing the metabolic syndrome. It can evolve to cirrhosis and hepatocellular carcinoma, with the consequent need for liver transplantation. Both genetic and environmental factors seem to be involved in the development and progression of the disease, but its physiopathology is not yet entirely clear. In view of this mounting epidemic phenomenon involving the youth, the study of NAFLD should be a priority for all health care systems. This review provides an overview of current and new clinical-histological concepts of pediatric NAFLD, going through possible implications into patho-physiolocical and therapeutic perspectives.

Cardiometabolic Risk Factors in Children

Considerable evidence has accrued that cardiovascular disease (CVD) has its beginnings during childhood, with some reports of endothelial damage occurring in early adolescence. Thus, early prevention and intervention on developing cardiometabolic risk factors is important. Presently, diet and exercise are strategic parts of any CVD prevention or treatment program. Although diet is important, the effects of exercise training or regular moderate-to-vigorous intensity physical activity go beyond simply modifying the traditional risk factors. For children, the majority of studies show that regular physical activity can lower elevated blood pressure, positively influence lipid profiles, reduce inflammation, and improve vascular functioning. These changes are most evident in children who exercise and lose weight. Despite these potential benefits of physical activity, not all studies on children have found positive effects of habitual physical activity on CVD risk factors. Reasons for these differences are discussed throughout this review. The literature also suggests that habitual physical activity, although meeting guidelines, may not be sufficient for all individuals to bring about changes; thus, to be an effective modality physical activity needs to increase beyond habitual levels or be of a moderate to vigorous intensity. This review provides recent evidence (since 2008) regarding the influence of physical activity on the cardiometabolic risk factors in children.

Impact of physical activity on inflammation: effects on cardiovascular disease risk and other inflammatory conditions

Since the 19(th) century, many studies have enlightened the role of inflammation in atherosclerosis, changing our perception of "vessel plaque due to oxidized lipoproteins", similar to a "rusted pipe", towards a disease with involvement of many cell types and cytokines with more complex mechanisms. Although "physical activity" and "physical exercise" are two terms with some differences in meaning, compared to sedentary lifestyle, active people have lower cardiovascular risk and lower inflammatory markers. Activities of skeletal muscle reveal "myokines" which have roles in both the immune system and adipose tissue metabolism. In vitro and ex-vivo studies have shown beneficial effects of exercise on inflammation markers. Meanwhile in clinical studies, some conflicting results suggested that type of activity, exercise duration, body composition, gender, race and age may modulate anti-inflammatory effects of physical exercise. Medical data on patients with inflammatory diseases have shown beneficial effects of exercise on disease activity scores, patient well-being and inflammatory markers. Although the most beneficial type of activity and the most relevant patient group for anti-inflammatory benefits are still not clear, studies in elderly and adult people generally support anti-inflammatory effects of physical activity and moderate exercise could be advised to patients with cardiovascular risk such as patients with metabolic syndrome.

Endothelial dysfunction, inflammation, and oxidative stress in obese children and adolescents: markers and effect of lifestyle intervention

With an increasing prevalence, pediatric obesity is often a prelude to adulthood obesity, and represents a major public health issue. Comorbidities are very common and severe in obese adults, justifying the search for earlier markers or risk factors for cardiovascular diseases in obese children. Endothelial dysfunction has been found to be present in the early stages of atherosclerosis, and can be non-invasively assessed with widely accepted and well-standardized techniques at the macrocirculation level. Endothelial dysfunction at the microcirculation level is less documented in obese children. Obesity in children has been repeatedly and independently correlated to endothelial dysfunction, inflammation and oxidative stress markers, although the relationship between these factors remains to be investigated. However, this would not only allow substantial improvements in risk stratification, but also provide essential data regarding the evolution of endothelial dysfunction in childhood obesity, especially during puberty when pro-inflammatory and pro-oxidative changes, with relative insulin resistance, occur. Therapeutic strategies such as lifestyle interventions in early childhood obesity appear all the more necessary, optimally including both exercise and diet because of their known effects on inflammatory and oxidative stress markers, potentially reversing endothelial dysfunction.

Intraduodenal administration of intact pea protein effectively reduces food intake in both lean and obese male subjects

BACKGROUND

Human duodenal mucosa secretes increased levels of satiety signals upon exposure to intact protein. However, after oral protein ingestion, gastric digestion leaves little intact proteins to enter the duodenum. This study investigated whether bypassing the stomach, through intraduodenal administration, affects hormone release and food-intake to a larger extent than orally administered protein in both lean and obese subjects.

METHODS

Ten lean (BMI:23.0±0.7 kg/m²) and ten obese (BMI:33.4±1.4 kg/m²) healthy male subjects were included. All subjects randomly received either pea protein solutions (250 mg/kg bodyweight in 0.4 ml/kg bodyweight of water) or placebo (0.4 ml/kg bodyweight of water), either orally or intraduodenally via a naso-duodenal tube. Appetite-profile, plasma GLP-1, CCK, and PYY concentrations were determined over a 2 h period. After 2 h, subjects received an ad-libitum meal and food-intake was recorded.

RESULTS

CCK levels were increased at 10(p<0.02) and 20(p<0.01) minutes after intraduodenal protein administration (IPA), in obese subjects, compared to lean subjects, but also compared to oral protein administration (OPA)(p<0.04). GLP-1 levels increased after IPA in obese subjects after 90(p<0.02) to 120(p<0.01) minutes, compared to OPA. Food-intake was reduced after IPA both in lean and obese subjects (-168.9±40 kcal (p<0.01) and -298.2±44 kcal (p<0.01), respectively), compared to placebo. Also, in obese subjects, food-intake was decreased after IPA (-132.6±42 kcal; p<0.01), compared to OPA.

CONCLUSIONS

Prevention of gastric proteolysis through bypassing the stomach effectively reduces food intake, and seems to affect obese subjects to a greater extent than lean subjects. Enteric coating of intact protein supplements may provide an effective dietary strategy in the prevention/treatment of obesity.

Ghrelin and PYY levels in adolescents with severe obesity: effects of weight loss induced by long-term exercise training and modified food habits

This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

Biological effects of obestatin

Obestatin, a 23-amino-acid peptide, is derived from the preproghrelin precursor. Obestatin was identified in 2005 as a hormone regulating food intake and energy, and having opposite effects to those of ghrelin. However, as studies have progressed, many disputes on the physiological function of obestatin have emerged. The food intake suppressive effects of obestatin have not been replicated in many studies. Nonetheless, many biological roles of obestatin have been revealed, and obestatin is thought to be associated with a variety of biological functions such as feeding, drinking, incretion, memory, and sleep, and with neuropsychiatric manifestations. The biological effects of obestatin will be reviewed in this article.

Plasma levels of leptin and soluble leptin receptor and polymorphisms of leptin gene -18G > A and leptin receptor genes K109R and Q223R, in survivors of childhood acute lymphoblastic leukemia

BACKGROUND

Approximately 20% of children and adolescents in Europe are overweight. Survivors of pediatric acute lymphoblastic leukemia (ALL) are at increased risk of overweight and obesity. The purpose of this study was to assess leptin and leptin soluble receptor levels, as well as polymorphisms of selected genes in survivors of pediatric ALL, and the influence of chemo- and radiotherapy on development of overweight in the context of leptin regulation.

METHODS

Eighty two patients (55% males), of median age 13.2 years (m: 4.8 years; M: 26.2 years) were included in the study. The ALL therapy was conducted according to modified Berlin-Frankfurt-Munster (BFM; n = 69) regimen or New York (n = 13) regimen. In 38% of patients cranial radiotherapy (CRT) was used in median dose of 18.2Gy (m: 14Gy; M: 24Gy). Median age at diagnosis was 4.5 (m: 1 year; M: 16.9 years) and median time from completion of ALL treatment was 3.2 years (m: 0.5 year; M: 4.3 years). Patients with BMI ≥85 percentile were classified as overweight. Correlation of plasma levels of leptin and leptin soluble receptor, and polymorphisms of leptin gene -18G > A, leptin receptor genes K109R and Q223R, and the overweight status were analyzed in relation to gender, intensity of chemotherapy (high intensity vs. standard intensity regimens) and to the use of CRT.

RESULTS

Significant differences of leptin levels in patients treated with and without CRT, both in the entire study group (22.2+/- 3.13 ng/ml vs. 14.9+/-1.6 ng/ml; p < 0.03) and in female patients (29.9+/-4.86 ng/ml vs. 16.9+/-2.44 ng/ml; p = 0.014), were found. Significant increase of leptin levels was also found in overweight patients compared to the non-overweight patients in the entire study group (29.2+/-2.86 ng/ml vs. 12.6+/-1.51 ng/ml; p < 0.0001), female patients (35.4+/-6.48 ng/ml vs. 18.4+/-2.5 ng/ml; p = 0.005), and male patients (25.7+/-2.37 ng/ml vs. 6.9+/-0.95 ng/ml; p < 0.0001). Negative correlation was observed for plasma levels of soluble leptin receptor and overweight status, with significant differences in overweight and non-overweight patients, both in the entire study group (18.2+/-0.75 ng/ml vs. 20.98+/-0.67 ng/ml; p = 0.017) and in male patients (18.2+/-1.03 ng/ml vs. 21.8+/- 1.11 ng/ml; p = 0.038). Significant (p < 0.05) negative correlation was found between leptin and leptin receptor levels in the entire group (correlation coefficient: 0.393) and in both gender subgroups (correlation coefficient in female patients: -0.427; in male patients: -0.396).

CONCLUSIONS

The prevalence of overweight in our cohort was higher than in general European population (31% vs 20%) and increased regardless of the use of CRT. Leptin and leptin receptor levels may be used as useful markers of high risk of becoming overweight in ALL survivors, particularly in females treated with CRT. Polymorphisms of leptin gene -18G > A and leptin receptor genes K109R and Q223R were not associated with overweight status in ALL survivors.

Nontraditional risk factors and biomarkers for cardiovascular disease: mechanistic, research, and clinical considerations for youth: a scientific statement from the American Heart Association

The rapid increase in the prevalence and severity of obesity in children is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide. Understanding the pathophysiology and improving the clinical management of cardiovascular disease involve a knowledge of novel risk factors and biomarkers. The clinical and mechanistic roles of these novel biological factors during childhood are currently being investigated. The goals of this scientific statement are to present the existing knowledge and theoretical framework of nontraditional risk factors for cardiovascular disease as they relate to children and adolescents, to describe the relevance and weight of available experimental and clinical evidence and the therapeutic implications pertaining to nontraditional risk factors in the pediatric population, and to stimulate further research with a goal of developing valid and reliable approaches to identify and validate novel risk factors that will aid in the clinical evaluation and perhaps prediction of cardiovascular disease in the pediatric population. Although several biomarkers are promising, substantial research is required before nontraditional risk factors can be used to identify and reduce cardiovascular disease risk in children and adolescents.