Randomized controlled trial to improve adiposity, inflammation, and insulin resistance in obese African-American and Latino youth

Effects of Dietary Sugar Reduction on Biomarkers of Cardiometabolic Health in Latino Youth: Secondary Analyses from a Randomized Controlled Trial

Pediatric obesity and cardiometabolic disease disproportionately impact minority communities. Sugar reduction is a promising prevention strategy with consistent cross-sectional associations of increased sugar consumption with unfavorable biomarkers of cardiometabolic disease. Few trials have tested the efficacy of pediatric sugar reduction interventions. Therefore, in a parallel-design trial, we randomized Latino youth with obesity (BMI ≥ 95th percentile) [n = 105; 14.8 years] to control (standard diet advice) or sugar reduction (clinical intervention with a goal of ≤10% of calories from free sugar) for 12-weeks. Outcomes included changes in glucose tolerance and its determinants as assessed by a 2-h frequently sample oral glucose tolerance test, fasting serum lipid profile (total cholesterol, HDL, LDL, triglycerides, cholesterol:HDL), and inflammatory markers (CRP, IL-6, TNF-α). Free sugar intake decreased in the intervention group compared to the control group [11.5% to 7.3% vs. 13.9% to 10.7% (% Energy), respectively, p = 0.02], but there were no effects on any outcome of interest (pall > 0.07). However, an exploratory analysis revealed that sugar reduction, independent of randomization, was associated with an improved Oral-disposition index (p < 0.001), triglycerides (p = 0.049), and TNF-α (p = 0.02). Dietary sugar reduction may have the potential to reduce chronic disease risks through improvements in beta-cell function, serum triglycerides, and inflammatory markers in Latino adolescents with obesity.

Effectiveness of Lifestyle Nutrition and Physical Activity Interventions for Childhood Obesity and Associated Comorbidities among Children from Minority Ethnic Groups: A Systematic Review and Meta-Analysis

Lifestyle physical activity (PA) and nutrition are known to be effective interventions in preventing and managing obesity-related comorbidities among adult populations but less so among children and adolescents. We examined the effectiveness of lifestyle interventions in children from minority ethnic populations in Western high-income countries (HICs). Our systematic review included 53 studies, involving 26,045 children from minority ethnic populations who followed lifestyle intervention programmes lasting between 8 weeks and 5 years with the aim of preventing and/or managing childhood obesity and associated comorbidities, including adiposity and cardiometabolic risks. The studies were heterogenous in terms of lifestyle intervention components (nutrition, PA, behavioural counselling) and settings (community vs. schools and after-school settings). Our meta-analysis included 31 eligible studies and showed no significant effects of lifestyle interventions when they focused on body mass index (BMI) outcomes (pooled BMI mean change = -0.09 (95% CI = -0.19, 0.01); p = 0.09). This was irrespective of the intervention programme duration (<6 months vs. ≥6 months), type (PA vs. nutrition/combined intervention) and weight status (overweight or obese vs. normal weight) as all showed nonsignificant effects in the sensitivity analysis. Nonetheless, 19 of the 53 studies reported reductions in BMI, BMI z-score and body fat percentage. However, the majority of lifestyle interventions adopting a quasi-design with combined primary and secondary obesity measures (11 out of 15 studies) were effective in reducing the obesity comorbidities of cardiometabolic risks, including metabolic syndrome, insulin sensitivity and blood pressure, in overweight and obese children. Preventing childhood obesity in high-risk ethnic minority groups is best achieved using combined PA and nutrition intervention approaches, which jointly target preventing obesity and its comorbidities, especially the outcomes of diabetes, hypertension and cardiovascular disease. Therefore, public health stakeholders should integrate cultural and lifestyle factors and contextualise obesity prevention strategies among minority ethnic groups in Western HICs.

Effects of a School-Based Nutrition, Gardening, and Cooking Intervention on Metabolic Parameters in High-risk Youth: A Secondary Analysis of a Cluster Randomized Clinical Trial

IMPORTANCE

Although school-based gardening programs for children have consistently been shown to improve dietary behaviors, no cluster randomized clinical trial (RCT) has evaluated the effects of a school-based gardening intervention on metabolic outcomes.

OBJECTIVE

To evaluate the effects of a school-based gardening, nutrition, and cooking intervention (Texas Sprouts) on changes in metabolic outcomes in elementary schoolchildren.

DESIGN, SETTING, AND PARTICIPANTS

This study was a secondary analysis of a cluster RCT, conducted over 3 years from 2016 to 2019, at low-income elementary schools with majority Hispanic students in the greater Austin, Texas, area. Data were analyzed from January to August 2022.

INTERVENTIONS

Texas Sprouts was 1 school year long (9 months) and consisted of (1) Garden Leadership Committee formation; (2) a 0.25-acre outdoor teaching garden; (3) 18 student gardening, nutrition, and cooking lessons taught by trained educators throughout the school year; and (4) 9 monthly parent lessons. The delayed intervention was implemented the following academic year and received an identical intervention.

MAIN OUTCOMES AND MEASURES

The following measures were obtained at baseline and postintervention (9 months): demographics via survey; measured height, weight, and body mass index parameters; and glucose, insulin, homeostatic model assessment of insulin resistance, and a lipid panel via an optional fasting blood draw.

RESULTS

Sixteen elementary schools were randomly assigned to either Texas Sprouts intervention (8 schools) or to delayed intervention (control, 8 schools). A total of 3302 children (aged 7-12 years) were enrolled in Texas Sprouts, and fasting blood samples were obtained from 1104 children (or 33% of those enrolled) at baseline. The final analytic sample included 695 children (307 boys [44.17%]; mean [SE] age, 9.28 [0.04] years; 480 Hispanic children [69.02%]; 452 [65.03%] eligible for free or reduced lunch) with complete demographic data and baseline and postintervention (9-month) fasting blood draws. Compared with control schools, children from Texas Sprouts schools had a 0.02% reduction in mean hemoglobin A1c (95% CI, 0.03%-0.14%; P = .005) and a 6.40 mg/dL reduction in mean low-density lipoprotein cholesterol (95% CI, 3.82-8.97 mg/dL; P = .048). There were no intervention effects on glucose, insulin, homeostatic model assessment of insulin resistance, or other lipid parameters.

CONCLUSIONS AND RELEVANCE

In this cluster RCT, Texas Sprouts improved glucose control and reduced low-density lipoprotein cholesterol in high-risk youth. These findings suggest that elementary schools should incorporate garden-based interventions as a way to improve metabolic parameters in children.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02668744.

On the Relationship Between Well-Being and Exercise Adherence for Children and Adolescents: A Systematic Mini Review

Although the close positive relationship between well-being and exercise adherence has been confirmed by numerous studies, it is still unclear whether this relationship exists for children and adolescents, because previous research mainly focuses on adults. The present review systematically explored the relationship between well-being ranging from individual to social aspects and exercise adherence based on extant studies. Seven studies including both quantitative and qualitative studies were analyzed. The results showed that well-being was not related to exercise adherence as strongly as expected. In some cases, well-being was even negatively associated with exercise adherence. Limited sample size, insensitive measurement of exercise adherence, gender, and mental and physical condition of children and adolescents might partially influence the relationship between well-being and exercise studies. However, the studies at hand are still in their infancy. More studies on the relationship between well-being and exercise adherence are needed for children and adolescents, especially in non-western countries.

Obesity, Body Image Dissatisfaction, and Sexual Dysfunction: A Narrative Review

With approximately two-thirds of the United States adult population classified as overweight or obese, obesity remains a critical public health concern. Obesity not only contributes to several health complications including type 2 diabetes mellitus and cardiovascular disease, but the condition is also associated with sexual dysfunction in both women and men. Despite evidence linking obesity and its concomitant pathophysiology to sexual problems, the potential roles of psychosocial factors such as body image are understudied. This narrative review evaluates the research linkages between obesity and sexual dysfunction, with particular attention to the potential effects of body image dissatisfaction. A literature search of biomedical and psychological databases was used to identify research pertaining to obesity, sexual function, and/or body image constructs. The pathophysiological effects of obesity on sexual function are well-documented in mechanistic studies and animal trials, often with corroboration in human clinical samples. However, very few studies examine obesity, body image, and sexual function in tandem. Body image dissatisfaction appears to independently impinge upon the sexual response cycle and mental health outcomes, irrespective of body weight. While obesity is often associated with negative body image appraisal, it is unclear whether these constructs exert additive, synergistic, or antagonistic effects on sexual responsivity. Additionally, overweight/obese individuals who exhibit higher levels of body image satisfaction or self-confidence appear to be protected from the deleterious effects of obesity on sexual satisfaction, at least to some extent. Greater reliance upon conceptual/theoretical models from the body image literature may better clarify the relationships between these constructs.

Impact of Physical Activity Intensity Levels on the Cardiometabolic Risk Status of Children: The Genobox Study

Childhood obesity has been related to metabolic syndrome and low-grade chronic inflammation. This study aimed to evaluate the impact of physical activity intensities and practice on inflammation, endothelial damage, and cardiometabolic risk factors in children. There were 513 participants, aged 6-14 years, recruited for the study. Physical activity was measured by accelerometry, and the children were classified into four groups according to quartiles of moderate to vigorous physical activity (MVPA) practice as very low active, low active, moderate active, and high active. Anthropometric measures, blood pressure, and plasma metabolic and proinflammatory parameters were analyzed. Very low active group presented a worse lipid profile and higher insulin, leptin, adiponectin, resistin, matrix metallopeptidase-9, and tissue plasminogen activator inhibitor-1, while lower levels of tumor necrosis factor-alpha, Type 1 macrophages, and interleukin 8 than high-active children. Regression analyses showed that a higher MVPA practice was associated with lower levels of triacylglycerols (β: -0.118; p = .008), resistin (β: -0.151; p = .005), tPAI (β: -0.105; p = .046), and P-selectin (β: -0.160; p = .006), independently of sex, age, and body mass index (BMI). In contrast, a higher BMI was associated with higher levels of insulin (β: 0.370; p < .001), Homeostasis Model Assessment (β: 0.352; p < .001), triacylglycerols (β: 0.209; p < .001), leptin (β: 0.654; p < .001), tumor necrosis factor-alpha (β: 0.182; p < .001), Type 1macrophages (β: 0.181; p < .001), and tissue plasminogen activator inhibitor (β: 0.240; p < .001), independently of sex, age, and MVPA. A better anthropometric, metabolic, and inflammatory profile was detected in the most active children; however, these differences were partly due to BMI. These results suggest that a higher MVPA practice and a lower BMI in children may lead to a better cardiometabolic status.

Imagine HEALTH: Randomized Controlled Trial of a Guided Imagery Lifestyle Intervention to Improve Obesity-Related Lifestyle Behaviors in Predominantly Latinx Adolescents

Introduction: To determine the effects of a novel lifestyle intervention combining lifestyle behavioral education with the complementary-integrative health modality of guided imagery (GI) on dietary and physical activity behaviors in adolescents. The primary aim of this study was to determine the incremental effects of the lifestyle education, stress reduction GI (SRGI), and lifestyle behavior GI (LBGI) components of the intervention on the primary outcome of physical activity lifestyle behaviors (sedentary behavior, light, moderate, and vigorous physical activity), as well as dietary intake behaviors, at the completion of the 12-week intervention. The authors hypothesized that the intervention would improve obesity-related lifestyle behaviors. Materials and Methods: Two hundred and thirty-two adolescent participants (aged 14-17 years, sophomore or junior year of high school) were cluster randomized by school into one of four intervention arms: nonintervention Control (C), Lifestyle education (LS), SRGI, and LBGI. After-school intervention sessions were held two (LS) or three (SRGI, LBGI) times weekly for 12 weeks. Physical activity (accelerometry) and dietary intake (multiple diet recalls) outcomes were assessed pre- and postintervention. Primary analysis: intention-to-treat (ITT) mixed-effects modeling with diagonal covariance matrices; secondary analysis: ad hoc subgroup sensitivity analysis using only those participants adherent to protocol. Results: ITT analysis showed that the Healthy Eating Index (HEI) increased in the LS group compared with C (p = 0.02), but there was no additional effect of GI. Among adherent participants, sedentary behavior was decreased stepwise relative to C in SRGI (d = -0.73, p = 0.004) > LBGI (d = -0.59, p = 0.04) > LS (d = -0.41, p = 0.07), and moderate + vigorous physical activity was increased in SRGI (d = 0.58, p = 0.001). Among adherent participants, the HEI was increased in LS and SRGI, and glycemic index reduced in LBGI. Conclusions: While ITT analysis was negative, among adherent participants, the Imagine HEALTH lifestyle intervention improved eating habits, reduced sedentary activity, and increased physical activity, suggesting that GI may amplify the role of lifestyle education alone for some key outcomes. CTR #NCT02088294.

Effects of Exercise in Addition to a Family-Based Lifestyle Intervention Program on Hepatic Fat in Children With Overweight

OBJECTIVE

Pediatric hepatic steatosis is highly prevalent and closely related to type 2 diabetes. This study aimed to determine whether the addition of supervised exercise to a family-based lifestyle and psycho-educational intervention results in greater reduction of percentage of hepatic fat (HF), adiposity, and cardiometabolic risk factors in children with overweight/obesity.

RESEARCH DESIGN AND METHODS

The study subjects of this nonrandomized, two-arm, parallel design clinical trial were 116 overweight/obese children (10.6 ± 1.1 years of age, 53.4% girls) living in Vitoria-Gasteiz (Spain). For 22 weeks, they followed either a lifestyle and psycho-education program (control intervention [CInt], N = 57), consisting of two family-based education sessions/month, or the same plus supervised exercise (intensive intervention [II], N = 59) focused mainly on high-intensity aerobic workouts (3 sessions/week, 90 min/session). The primary outcome was the change in percentage of HF (as measured by MRI) between baseline and the end of the intervention period. Secondary outcomes included changes in BMI, fat mass index (FMI), abdominal fat (measured by DEXA), blood pressure, triglycerides, HDL, LDL, γ-glutamyl transferase, glucose, and insulin concentrations.

RESULTS

A total of 102 children completed the trial (N = 53 and N = 49 in the CInt and II groups, respectively). Percentage of HF decreased only in the II group (-1.20 ± 0.31% vs. 0.04 ± 0.30%, II and CInt groups, respectively), regardless of baseline value and any change in adiposity (P < 0.01). BMI, FMI, abdominal fat (P ≤ 0.001), and insulin (P < 0.05) were reduced in both groups.

CONCLUSIONS

Multicomponent intervention programs that include exercise training may help to reduce adiposity, insulin resistance, and hepatic steatosis in overweight/obese children.

Understanding low adherence to an exercise program for adolescents with obesity: the HEARTY trial

INTRODUCTION

Despite efforts to improve adherence to physical activity interventions in youth with obesity, low adherence and attrition remain areas of great concern.

OBJECTIVE

The study was designed to determine which physiological and/or psychological factors predicted low adherence in adolescents with obesity enrolled in a 6-month exercise intervention study aimed to improve body composition.

METHODS

Three hundred four adolescents with obesity aged 14-18 years who volunteered for the HEARTY (Healthy Eating Aerobic and Resistance Training in Youth) randomized controlled trial completed physiological (body mass index, waist circumference, per cent body fat, resting metabolic rate and aerobic fitness) and psychological (body image, mood, self-esteem and self-efficacy) measures.

RESULTS

One hundred forty-one out of 228 (62%) randomized to exercise groups had low adherence (completed <70% of the prescribed four exercise sessions per week) to the intervention protocol. Logistic regression revealed that there were no baseline demographic or physiological variables that predicted low adherence in the participants. Appearance concern (a subscale of body image) (odds ratio [OR] 1.46, 95% confidence interval [CI]: 1.01, 2.1, P = 0.04), depressive mood (OR 1.12, 95% CI: 1.01, 1.23, P = 0.03) and confused mood (OR 1.16, 95% CI: 1.05, 1.27, P = 0.003) (two subscales of mood) were significant predictors of low adherence.

CONCLUSIONS

Adolescents with obesity who had higher appearance concerns and depressive and confused moods were less likely to adhere to exercise. Body image and mood should be screened to identify adolescents who may be at high risk of poor adherence and who may need concurrent or treatment support to address these psychological issues to derive maximal health benefits from an exercise programme.

What Is the Role of Resistance Exercise in Improving the Cardiometabolic Health of Adolescents with Obesity?

Traditionally, individuals with obesity have been encouraged to participate in aerobic exercise for long-term weight management and improved obesity-related health outcomes. Recently, resistance exercise has become a popular mode of exercise among youth with obesity. However, to date, the literature is mixed as to whether resistance exercise training alone improves body weight, fat free mass, body composition, cardiovascular risk factors, or atherogenic lipoprotein profiles. The limited research in this area suggests potential sex differences in response to resistance training in youth. The literature is more consistent in demonstrating improvements in muscular fitness and insulin resistance independent of caloric restriction and weight loss. Although major health organizations recommend combining aerobic and resistance training, little research has examined the effects of their combination versus their individual effects, thus it is unclear whether their combination is associated with benefits that extend beyond those of either exercise modality alone. The purpose of this review is to examine the effects of resistance exercise on body composition and the health risk factors associated with cardiovascular disease and type 2 diabetes in youth with obesity.

Racial Discrimination and Low Household Education Predict Higher Body Mass Index in African American Youth

OBJECTIVE

The purpose of this study was to examine the relationships between environmental factors, including household education, community violence exposure, racial discrimination, and cultural identity, and BMI in African American adolescents.

METHODS

A community-based sample of 198 African American youth (120 girls, 78 boys; ages 11-19 years) from Washtenaw County, Michigan, were included in this analysis. Violence exposure was assessed by using the Survey of Children's Exposure to Community Violence; racial discrimination by using the Adolescent Discrimination Distress Index; cultural identity by using the Acculturation, Habits, and Interests Multicultural Scale for Adolescents; and household education by using a seven-category variable. Measured height and body weight were used to calculate BMI.

RESULTS

Racial discrimination was positively associated with BMI, whereas household education was inversely associated with BMI in African American adolescents (discrimination: β = 0.11 ± 0.04, p = 0.01; education: β = -1.13 ± 0.47, p = 0.02). These relationships were significant when accounting for the confounding effects of stress, activity, diet, and pubertal development. Significant gender interactions were observed with racial discrimination and low household education associated with BMI in girls only (discrimination: β = 0.16 ± 0.05, p = 0.003; education: β = -1.12 ± 0.55, p = 0.045). There were no significant relationships between culture, community violence exposure, and BMI (all p's > 0.05).

CONCLUSION

Environmental factors, including racial discrimination and low household education, predicted higher BMI in African American adolescents, particularly among girls. Longitudinal studies are needed to better understand the mechanisms by which these environmental factors increase obesity risk in African American youth.

The Effect of Chronic Exercise Training on Leptin: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Leptin is a hormone associated with satiety, lipid oxidation, energy expenditure, and energy homeostasis. To date, the current body of research examining the effect of chronic exercise training on leptin has yielded inconsistent results.

OBJECTIVE

The purpose of this meta-analysis was to provide a quantitative estimate of the magnitude of change in leptin levels following participation in exercise interventions lasting ≥ 2 weeks.

METHODS

All studies included were peer-reviewed and published in English. To be included, studies randomized human participants to an exercise training group or non-exercise comparison group for an exercise training intervention. Leptin levels were measured at baseline, during, and/or after completion of the exercise training program. Random-effects models were used to aggregate a mean effect size (ES) and 95% confidence intervals (CIs), and identify potential moderators.

RESULTS

Seventy-two randomized controlled trials met the inclusion criteria and resulted in 107 effects (n = 3826). The mean ES of 0.24 (95% CI 0.16-0.32, p < 0.0001) indicated a decrease in leptin following an exercise training program. A decrease in %Fat (β = - 0.07, p < 0.01) was associated with a decrease in leptin after accounting for the type of control group (β = - 0.38, p < 0.0001) used in each study.

CONCLUSION

These results suggest that engaging in chronic exercise training (≥ 2 weeks) is associated with a decrease in leptin levels for individuals regardless of age and sex. However, a greater decrease in leptin occurred with a decreased percentage of body fat.

Objectively Measured Sedentary Behavior, Physical Activity, and Cardiometabolic Risk in Hispanic Youth: Hispanic Community Health Study/Study of Latino Youth

Context

Time spent in moderate-to-vigorous physical activity (MVPA), but not in sedentary behavior (SB), is related to cardiometabolic risk among non-Hispanic white youth.

Objective

Examine associations of SB and MVPA with cardiometabolic risk factors among Hispanic/Latino youth.

Design

Cross-sectional analysis.

Setting

Four US communities.

Participants

Hispanic/Latino youth (N = 1,426) ages 8 to 16 years.

Measurements

Associations of MVPA and SB, measured using 7-day accelerometer data (independent variables), with markers of glucose and lipid metabolism, inflammation, and endothelial function (dependent variables), were assessed in multivariable linear regression models while adjusting for sociodemographic characteristics and accelerometer wear time. Additional models controlled for obesity measures.

Results

SB comprised a mean (SD) of 75% (13%) of accelerometer wear time; mean (SD) time of MVPA was 35 min/d (22 min/d). Deleterious levels of high-density lipoprotein-cholesterol (HDL-C), triglycerides, insulin resistance, C-reactive protein, and plasminogen activator inhibitor-1 were associated with lower levels of MVPA and higher levels of SB (all P < 0.05). Associations of MVPA with log-transformed triglyceride concentrations (β per 15-min/d increment, -0.039; SE, 0.018; P = 0.037) and SB with HDL-C (β per 30-min/d increment, -0.63; SE, 0.26; P = 0.018), but not those with other markers, remained significant after adjusting for MVPA or SB and further adjustment for body mass index and waist circumference. Higher SB tertiles were associated with lower soluble receptor for advanced glycation end products in fully adjusted models (P for trend = 0.037).

Conclusions

Physiological precursors of diabetes and cardiovascular disease were associated with MVPA and SB among US Hispanic/Latino youth, a group that bears a disproportionate burden of metabolic disorders.

Type 2 diabetes mellitus risk and exercise: is resistin involved?

Obesity and associated disorders such as type 2 diabetes mellitus (T2DM) pose an increasing risk to the health of both individuals and society. Adipose tissue is an active endocrine organ, secreting many hormones, known as adipokines. Evidence suggests that one suggest adipokine, resistin, may be elevated in the plasma of individuals with T2DM, and early reports indicated that this may contribute to the impaired glucose tolerance and insulin resistance observed in T2DM, hence its name, resistin, however subsequent evidence suggests it may have a proinflammatory role. Performing regular exercise and dietary interventions improve insulin sensitivity and glucose tolerance in the majority of individuals with T2DM, and we hypothesized that plasma resistin levels may drop in individuals following a long term aerobic and/or resistance exercise intervention program. Articles analyzing the effects of exercise on serum resistin levels were therefore analyzed. Articles were selected and analyzed based on a minimum aerobic and/or resistance training program of 2 sessions per week for 12 weeks. Plasma resistin levels decreased following either endurance aerobic exercise and/or resistance training plans in individuals with obesity and/or insulin resistance, although this was not related to BMI change. Exercise intervention programs generally showed potentially beneficial changes in plasma resistin concentrations. It is possible these effects are mediated through exercise-induced decreases in inflammation via anti-inflammatory cytokine release rather than alterations in glucose metabolism and reductions in BMI per se. A possible link between resistin, exercise and T2DM is discussed.

Evidence-Based Exercise Recommendations to Reduce Hepatic Fat Content in Youth- a Systematic Review and Meta-Analysis

The main purposes of this study were to elucidate the effects of supervised-exercise training (ET) interventions on hepatic fat content and on non-alcoholic fatty liver disease (NAFLD) prevalence in children and adolescents and to provide information about the optimal ET prescription (type, intensity, volume, and frequency) needed to reduce hepatic fat content in youths. Supervised-ET interventions performed in children and adolescents (6-19 years) that provided results of exercise effects on hepatic fat content or NAFLD prevalence were included. Supervised-exercise significantly reduced hepatic fat content compared to the control groups. Lifestyle interventions that included supervised-ET significantly reduced the prevalence of NAFLD. This systematic review and meta-analysis shows that supervised-ET could be an effective strategy in the management and prevention of NAFLD in children and adolescents. Both aerobic and resistance ET, at vigorous or moderate-to-vigorous intensities, with a volume ≥60 min/session and a frequency ≥3 sessions/week, aiming to improve cardiorespiratory fitness and muscular strength, had benefits on hepatic fat content reduction in youth. These data concur with the international recommendations of physical activity for health promotion in youth and may be useful when designing ET programs to improve and prevent hepatic steatosis in the pediatric population.

Engaging African American Adolescents and Stakeholders to Adapt Interpersonal Psychotherapy for Weight Gain Prevention

Developing culturally appropriate obesity prevention programs for African American (AA) adolescent girls that account for psychological risk factors is paramount to addressing health disparities. The current study was part of an investigation utilizing a community-based participatory research framework to gather qualitative data from urban AA girls, their caregivers, and community health liaisons to develop a novel obesity prevention program based on interpersonal psychotherapy for the prevention of excessive weight gain (IPT-WG). In the current study with urban AAs, data from seven focus groups (total sample size, N = 40) were analyzed using thematic analysis. Participants identified problematic eating behaviors, including binge or loss of control eating; highlighted the importance of interpersonal relationships, mood functioning, and eating; and supported the tenets of IPT-WG. While features of IPT-WG generally resonated with participants, culturally based modifications were suggested. These data will be used to inform the development of a culturally relevant IPT-WG program.

The effect of diet or exercise on ectopic adiposity in children and adolescents with obesity: a systematic review and meta-analysis

OBJECTIVE

Ectopic fat depostion in youth with obesity is associated with an increased cardiovascular disease risk. The aim of this meta-analysis was to summarize the evidence for the use of diet and/or exercise on ectopic adiposity in this population.

METHODS

A systematic literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. Clinical trials that assessed ectopic fat deposition and included study arms with diet and/or exercise were searched in PubMed, PEDro and the Cochrane database.

RESULTS

Hepatic fat content and intramyocellular lipid content were described in nine studies and three studies, respectively. Most studies included teenagers, and study duration ranged between 3 and 12 months without follow-up. Using random-effects weights, the standardized mean difference of the change in hepatic adiposity (totalling 320 subjects) was -0.54 Hedges' g (95% confidence interval: -0.69 to -0.38 with p < 0.0001). By re-expressing this effect size, it is seen that diet and/or exercise results in an absolute reduction of intrahepatic lipid with 2%, which accords with a relative reduction up to 70%. Although there were significant ameliorations of insulin sensitivity, no significant changes in intramyocellular lipid were observed.

CONCLUSIONS

This meta-analysis showed that diet and/or exercise is effective to reduce hepatic adiposity in youth with obesity.

Effectiveness of a low-fructose and/or low-sucrose diet in decreasing insulin resistance (DISFRUTE study): study protocol for a randomized controlled trial

BACKGROUND

Research published to date on the relationship between insulin resistance (IR) and fructose consumption is scarce, has used different methods, and has yielded sometimes contradictory results. This study aims to determine whether a low-fructose and/or low-sucrose diet supervised by a physician or nurse decreases IR compared to a standard diet.

METHODS/DESIGN

This field trial is located at primary care centers. The participants are adults aged 29 to 66 years, with a Body mass Index (BMI) between 29 and 40.99 kg/m2 and without diabetes. To date, 245 participants have been assigned randomly to the low-fructose diet intervention group (LFDI) at health centers in the western health service zone of Tenerife island, and 245 to the standard-diet control group (SDC) at health centers in the eastern health service zone. Recruitment is opportunistic and is carried out by physicians and nurses at participating health centers. Initially (baseline), and after 24 weeks of intervention, dietary records, physical activity, waist circumference, BMI, blood pressure, fasting blood glucose and insulin concentrations (HOMA2-IR) and lipid profile are recorded; blood glucose and insulin and lipid profile are also recorded 2 h after a 75-g glucose overload. After 48 weeks (24 weeks after the intervention), fasting blood samples are again obtained and a physical examination is performed. All tests and measures are repeated and recorded except dietary records, physical activity and oral glucose overload. Low-fructose diets are designed by calculating free and total (free + fructose associated with sucrose) fructose contents in standard diets, and removing foods with a fructose content in the highest quartile for the amounts in the standard diet. Participants in both groups are prescribed a diet that contains 30 to 40% less than the participant's energy requirements. The primary endpoint is change in HOMA2-IR between baseline and week 24, and other outcomes are change in HDL-cholesterol, LDL-cholesterol, triglycerides , waist circumference to height ratio and BMI. The secondary endpoint is change in HOMA2-IR between week 24 and week 48 together with the outcomes noted above. Comparisons between groups for variables used to indicate IR levels are done with a Student's t test for unpaired variables or the Mann-Whitney U test if the distribution is not normal. Multivariate regression models will be used to control for confounding factors not accounted for in the study design, and for independent prognostic factors.

DISCUSSION

If the dietary intervention being tested, i.e., a diet low in fructose/sucrose, is able to reduce IR, the results - if translated into regular clinical practice - could provide a hitherto unavailable tool to prevent type-2 diabetes mellitus.

TRIAL REGISTRATION

ISRCTN, ID: ISRCTN41579277 . Registered retrospectively on 15 November 2016.

Resistance Training Effects on Metabolic Function Among Youth: A Systematic Review

PURPOSE

This systematic review evaluates the relationship between resistance training and metabolic function in youth.

METHODS

PubMed, Embase, Cochrane Library, Web of Science, CINAHL, and ClinicalTrials. gov were searched for articles that (1): studied children (2); included resistance training (3); were randomized interventions; and (4) reported markers of metabolic function. The selected studies were analyzed using the Cochrane Risk-of-Bias Tool.

RESULTS

Thirteen articles met inclusion criteria. Mean age ranged from 12.2 to 16.9 years, but most were limited to high school (n = 11) and overweight/obese (n = 12). Sample sizes (n = 22-304), session duration (40-60min), and intervention length (8-52 wks) varied. Exercise frequency was typically 2-3 d/wk. Resistance training was metabolically beneficial compared with control or resistance plus aerobic training in 5 studies overall and 3 out of the 4 studies with the fewest threats to bias (p ≤ .05); each was accompanied by beneficial changes in body composition, but only one study adjusted for change in body composition.

CONCLUSIONS

Limited evidence suggests that resistance training may positively affect metabolic parameters in youth. Well-controlled resistance training interventions of varying doses are needed to definitively determine whether resistance training can mitigate metabolic dysfunction in youth and whether training benefits on metabolic parameters are independent of body composition changes.

Metabolic effects of resistance or high-intensity interval training among glycemic control-nonresponsive children with insulin resistance

BACKGROUND

Little evidence exists on which variables of body composition or muscular strength mediates more glucose control improvements taking into account inter-individual metabolic variability to different modes of exercise training.

OBJECTIVE

We examined 'mediators' to the effects of 6-weeks of resistance training (RT) or high-intensity interval training (HIT) on glucose control parameters in physically inactive schoolchildren with insulin resistance (IR). Second, we also determined both training-induce changes and the prevalence of responders (R) and non-responders (NR) to decrease the IR level.

METHODS

Fifty-six physically inactive children diagnosed with IR followed a RT or supervised HIT program for 6 weeks. Participants were classified based on ΔHOMA-IR into glycemic control R (decrease in homeostasis model assessment-IR (HOMA-IR) <3.0 after intervention) and NRs (no changes or values HOMA-IR⩾3.0 after intervention). The primary outcome was HOMA-IR associated with their mediators; second, the training-induced changes to glucose control parameters; and third the report of R and NR to improve body composition, cardiovascular, metabolic and performance variables.

RESULTS

Mediation analysis revealed that improvements (decreases) in abdominal fat by the waist circumference can explain more the effects (decreases) of HOMA-IR in physically inactive schoolchildren under RT or HIT regimes. The same analysis showed that increased one-maximum repetition leg-extension was correlated with the change in HOMA-IR (β=-0.058; P=0.049). Furthermore, a change in the waist circumference fully mediated the dose-response relationship between changes in the leg-extension strength and HOMA-IR (β'=-0.004; P=0.178). RT or HIT were associated with significant improvements in body composition, muscular strength, blood pressure and cardiometabolic parameters irrespective of improvement in glycemic control response. Both glucose control RT-R and HIT-R (respectively), had significant improvements in mean HOMA-IR, mean muscular strength leg-extension and mean measures of adiposity.

CONCLUSIONS

The improvements in the lower body strength and the decreases in waist circumference can explain more the effects of the improvements in glucose control of IR schoolchildren in R group after 6 weeks of RT or HIT, showing both regimes similar effects on body composition or muscular strength independent of interindividual metabolic response variability.

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.

Can metabolic function and physical fitness improve without weight loss for inactive, obese, Hispanic adolescents? A feasibility study

INTRODUCTION

A case series that examines the effects of a 12-week combined resistance and aerobic training program for four sedentary obese, Hispanic adolescents without weight loss.

SUBJECTS/METHODS

Baseline and post-intervention anthropometric, metabolic and physical fitness measures were obtained. Body composition, hepatic, visceral, and intramuscular fat contents were analyzed via imaging. Fasting levels of alanine transaminase (ALT), insulin, glucose, free fatty acids, triglycerides, high- and low-density lipoproteins (LDL), and C-reactive protein were obtained via blood samples.

RESULTS

Two subjects decreased their glucose levels by 1.86% and 4.06%. Subjects 1, 3, and 4 increased their lean body mass by 4.12%, 9.70%, and 5.48%. ALT was reduced 13.0%, 16.0%, and 35.7% for subjects 2, 3, and 4, respectively. LDLs were reduced by 37.7%, 4.5%, and 7.5% for subjects 1, 2, and 3. Triglycerides were reduced by 25.4%, 37.8%, and 4.6% for subjects 1, 2, and 3. Visceral fat reductions by 16.5%, 14.2%, and 13.0% occurred for subjects 1, 2, and 3. C-reactive protein was reduced for subjects 1, 2, and 3 by 19.4%, 16.3%, and 32.0%.

CONCLUSION

Expected directions of change were made for most indicators of metabolic function and body composition, but measures of physical fitness improved for all four subjects.

Explaining Disparities in Youth Aerobic Fitness and Body Mass Index: Relative Impact of Socioeconomic and Minority Status

BACKGROUND

To advance research on youth fitness promotion it is important to understand factors that may explain the disparities in fitness.

METHODS

We evaluated data from the FitnessGram NFL PLAY60 Partnership Project to examine school factors influencing aerobic capacity (AC) and body mass index (BMI) in schoolchildren. Individual observations for AC (157,971 students from 675 schools) and BMI (178,274 students from 630 schools) were aggregated to compute the percentage of students achieving the Healthy Fitness Zone (HFZ). We examined achievements using adjusted linear regression models with socioeconomic status (SES), minority status, region, enrollment, and grade as factors.

RESULTS

The mean HFZ for AC and BMI were 51.6% and 56.9%, respectively. SES, minority status, and enrollment were all significantly associated with AC HFZ among boys, and SES and enrollment were significant predictors of AC HFZ in girls. SES and location were significantly related to BMI HFZ among boys but only SES significantly predicted BMI HFZ in girls. Schools with higher SES had higher AC and BMI HFZ achievements.

CONCLUSIONS

SES was consistently associated with health-related fitness, independent of sex, but not minority status.

Dietary fibre linked to decreased inflammation in overweight minority youth

OBJECTIVE

The objective of this study was to examine the relationship between diet and inflammation, and adiposity in minority youth.

DESIGN AND METHODS

The study was designed as a cross-sectional analysis of 142 overweight (≥85th body mass index percentile) Hispanic and African-American adolescents (14-18 years) with the following measures: anthropometrics, adiposity via magnetic resonance imaging, dietary intake via 24-h dietary recalls, and inflammation markers from fasting blood draws utilizing a multiplex panel. Partial correlations were estimated and analysis of covariance (ancova) models fit to examine the relationship among dietary variables, inflammation markers and adiposity measures with the following a priori covariates: Tanner stage, ethnicity, sex, total energy intake, total body fat and total lean mass.

RESULTS

Inference based on ancova models showed that the highest tertile of fibre intake (mean intake of 21.3 ± 6.1 g d(-1) ) vs. the lowest tertile of fibre intake (mean intake of 7.4 ± 1.8 g d(-1) ) was associated with 36% lower plasminogen activator inhibitor-1 (P = 0.02) and 43% lower resistin (P = 0.02), independent of covariates. Similar results were seen for insoluble fibre. No other dietary variables included in this study were associated with inflammation markers.

CONCLUSIONS

These results suggest that increases in dietary fibre could play an important role in lowering inflammation and therefore metabolic disease risk in high-risk minority youth.

Potential link between excess added sugar intake and ectopic fat: a systematic review of randomized controlled trials

CONTEXT

The effect of added sugar intake on ectopic fat accumulation is a subject of debate.

OBJECTIVE

A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to examine the potential effect of added sugar intake on ectopic fat depots.

DATA SOURCES

MEDLINE, CAB Abstracts, CAB Global Health, and EBM (Evidence-Based Medicine) Reviews - Cochrane Central Register of Controlled Trials databases were searched for studies published from 1973 to September 2014.

DATA EXTRACTION

RCTs with a minimum of 6 days' duration of added sugar exposure in the intervention group were selected. The dosage of added sugar intake as a percentage of total energy was extracted or calculated. Means and standard deviations of pre- and post-test measurements or changes in ectopic fat depots were collected.

DATA SYNTHESIS

Fourteen RCTs were included. Most of the studies had a medium to high risk of bias. Meta-analysis showed that, compared with eucaloric controls, subjects who consumed added sugar under hypercaloric conditions likely increased ectopic fat, particularly in the liver (pooled standardized mean difference = 0.9 [95%CI, 0.6-1.2], n = 6) and muscles (pooled SMD = 0.6 [95%CI, 0.2-1.0], n = 4). No significant difference was observed in liver fat, visceral adipose tissue, or muscle fat when isocaloric intakes of different sources of added sugars were compared.

CONCLUSIONS

Data from a limited number of RCTs suggest that excess added sugar intake under hypercaloric diet conditions likely increases ectopic fat depots, particularly in the liver and in muscle fat. There are insufficient data to compare the effect of different sources of added sugars on ectopic fat deposition or to compare intake of added sugar with intakes of other macronutrients. Future well-designed RCTs with sufficient power and duration are needed to address the role of sugars on ectopic fat deposition.

Recruitment and retention in obesity prevention and treatment trials targeting minority or low-income children: a review of the clinical trials registration database

Background

Efforts to recruit and retain participants in clinical trials are challenging, especially in studies that include minority or low-income children. To date, no studies have systematically examined recruitment and retention strategies and their effectiveness in working successfully with this population. We examined strategies employed to recruit or retain minority or low-income children in trials that included an obesity-related behavior modification component.

Methods

First, completed home-, community-, and school-based trials involving minority or low-income children aged 2–17 years were identified in a search of the ClinicalTrials.gov registry. Second, a PubMed search of identified trials was conducted to locate publications pertinent to identified trials. Recruitment and retention rates were calculated for studies that included relevant information.

Results

Our final analytic sample included 43 studies. Of these, 25 studies reported recruitment or retention strategies, with the amount of information varying from a single comment to several pages; 4 published no specific information on recruitment or retention; and 14 had no publications listed in PubMed. The vast majority (92 %) of the 25 studies reported retention rates of, on average, 86 %. Retention rates were lower in studies that: targeted solely Hispanics or African Americans (vs. mixed races of African Americans, whites, and others); involved children and parents (vs. children only); focused on overweight or obese children (vs. general children), lasted ≥1 year (vs. <1 year), were home or community-based (vs. school-based), included nutrition and physical activity intervention (vs. either intervention alone), had body mass index or other anthropometrics as primary outcome measures (vs. obesity-related behavior, insulin sensitivity, etc.). Retention rates did not vary based on child age, number of intervention sessions, or sample size.

Conclusions

Variable amounts of information were provided on recruitment and retention strategies in obesity-related trials involving minority or low-income children. Although reported retention rates were fairly high, a lack of reporting limited the available information. More and consistent reporting and systematic cataloging of recruitment and retention methods are needed. In addition, qualitative and quantitative studies to inform evidence-based decisions in the selection of effective recruitment and retention strategies for trials including minority or low-income children are warranted.

Changes in whole-body fat distribution, intrahepatic lipids, and insulin resistance of obese adolescents during a low-level lifestyle intervention

The aim of this study was to analyze changes in adipose tissue (AT) distribution, intrahepatic lipids (IHL), and insulin resistance (IR) among a group of obese adolescents undergoing a 7-months low-level lifestyle intervention. Thirty-nine obese Caucasian adolescents (mean age 13.9 years, body mass index standard deviation score (BMI-SDSLMS) 2.14) were included. AT and IHL were determined by T1-weighted magnetic resonance (MR) imaging and single-voxel MR spectroscopy; IR was estimated using the homeostatic model assessment (HOMA-IR). The lifestyle intervention led to a reduction of both BMI-SDSLMS (boys 2.27 to 2.17; girls 2.00 to 1.82) and HOMA-IR (boys 6.1 to 4.4 (p = 0.008); girls 6.2 to 4.7 (p = 0.030)). IHL dropped in both genders (boys 7.5 to 4.3 %; girls 4.6 to 3.4 %) positively correlating with HOMA-IR (boys r = 0.52; girls r = 0.68), while in contrast visceral AT did not change significantly.

CONCLUSIONS

Although the lifestyle intervention only slightly reduced BMI-SDSLMS, insulin sensitivity improved in both genders and came along with a marked reduction of IHL. This suggests that IHL might play the dominant role regarding insulin resistance in the youth, especially if compared to other AT compartments such as visceral AT.

WHAT IS KNOWN

• MR imaging/spectroscopy can be used to evaluate body fat distribution and intrahepatic lipids in the youth. • The strength of associations between body fat compartments and insulin resistance is under scientific debate.

WHAT IS NEW

• The study emphasizes that even a low-level lifestyle intervention has a beneficial effect. • The study suggests that intrahepatic lipids are an important factor in the development of insulin resistance.

Windows of opportunity for physical activity in the prevention of obesity

Tackling increasing rates of obesity is likely to be a defining feature of health care over the next several decades. Adult obesity is a persistent and treatment-resistant problem. Consequently, an emerging theme in the literature is to commence prevention efforts earlier in the developmental time course. This view is based primarily on epidemiological data demonstrating a link between traits manifesting early during development and increased obesity risk in adulthood. Physical activity is a perennial factor in discussions of obesity prevention. However, the optimal timing and type of physical activity interventions to commence remains unclear. Critical developmental windows of plasticity may afford time-limited opportunities to shape body composition across the life course; however, physical activity has not been explicitly considered in these discussions. Although animal models suggest that physical activity commenced earlier in development has differential effects on obesity onset compared to physical activity commenced in adulthood, human research is lacking. In this conceptual review, we consider physical activity during critical developmental periods as a way to mitigate obesity risk later in life.

Sugar-sweetened beverage, diet soda, and fatty liver disease in the Framingham Heart Study cohorts

BACKGROUND & AIMS

Non-alcoholic fatty liver disease affects ∼30% of US adults, yet the role of sugar-sweetened beverages and diet soda on these diseases remains unknown. We examined the cross-sectional association between intake of sugar-sweetened beverages or diet soda and fatty liver disease in participants of the Framingham Offspring and Third Generation cohorts.

METHODS

Fatty liver disease was defined using liver attenuation measurements generated from computed tomography in 2634 participants. Alanine transaminase concentration, a crude marker of fatty liver disease, was measured in 5908 participants. Sugar-sweetened beverage and diet soda intake were estimated using a food frequency questionnaire. Participants were categorized as either non-consumers or consumers (3 categories: 1 serving/month to <1 serving/week, 1 serving/week to <1 serving/day, and ⩾1 serving/day) of sugar-sweetened beverages or diet soda.

RESULTS

After adjustment for age, sex, smoking status, Framingham cohort, energy intake, alcohol, dietary fiber, fat (% energy), protein (% energy), diet soda intake, and body mass index, the odds ratios of fatty liver disease were 1, 1.16 (0.88, 1.54), 1.32 (0.93, 1.86), and 1.61 (1.04, 2.49) across sugar-sweetened beverage consumption categories (p trend=0.04). Sugar-sweetened beverage consumption was also positively associated with alanine transaminase levels (p trend=0.007). We observed no significant association between diet soda intake and measures of fatty liver disease.

CONCLUSION

In conclusion, we observed that regular sugar-sweetened beverage consumption was associated with greater risk of fatty liver disease, particularly in overweight and obese individuals, whereas diet soda intake was not associated with measures of fatty liver disease.

Vegetable consumption is linked to decreased visceral and liver fat and improved insulin resistance in overweight Latino youth

There are limited data on the influence of vegetable consumption on adiposity and metabolic health, specifically nonstarchy vegetables and vegetables that are dark green and deep orange/yellow (also known as nutrient-rich vegetables). Our study examines the relationship between vegetable intake and adiposity, liver fat, and insulin dynamics in overweight Latino youth. This cross-sectional study of 175 overweight (body mass index ≥85th percentile) Latino youth (aged 8 to 18 years), with data collected during 2006-2011, included the following: dietary intake via multiple 24-hour recalls, total body fat via dual-energy x-ray absorptiometry, adipose tissue distribution and liver fat via magnetic resonance imaging, and insulin dynamics via frequently sampled intravenous glucose tolerance test. Linear regression and analysis of covariance were used for analysis, with the following a priori covariates: age, sex, energy intake, and total body fat. Participants who consumed the most nonstarchy vegetables (mean intake=1.7±1.0 servings/day) compared with the least (mean intake=0.1±0.1 servings/day) had 44% less liver fat (10.0%±8.5% vs 5.6%±8.7%; P=0.01). Nutrient-rich vegetable intake was positively correlated with insulin sensitivity (r=0.19; P=0.03). Consumers of nutrient-rich vegetables (mean intake=0.3±0.4 servings/day [n=107]), compared with nonconsumers (n=68), had 31% increased insulin sensitivity (1.6±1.6 vs 2.1±1.3×10(⁻⁴)/min/μU/mL; P=0.03) and 17% less visceral adipose tissue (2.3±0.9 vs 1.9±0.7 L; P=0.01). Consumption of specific vegetable types by overweight Latino youth is associated with positive metabolic outcomes, including reduced visceral and liver fat and risk factors for type 2 diabetes, even when consumed in small quantities. These may be relevant targets for interventions.

Outside-of-school time obesity prevention and treatment interventions in African American youth

Outside-of-school time (OST; i.e. before/after-school hours, summer time), theory-based interventions are potential strategies for addressing increased obesity among African American youth. This review assessed interventions across multiple settings that took place during OST among African American youth aged 5-18 years old. Seven databases were searched for studies published prior to October 2013; 28 prevention and treatment interventions that assessed weight or related behaviours as a primary or secondary outcome were identified. Overall, these studies reported heterogeneous intervention length, theoretical frameworks, methodological quality, outcomes, cultural adaption and community engagement; the latter two attributes have been identified as potentially important intervention strategies when working with African Americans. Although not always significant, generally, outcomes were in the desired direction. When examining programmes by time of intervention (i.e. after-school, summer time, time not specified or multiple time periods), much of the variability remained, but some similarities emerged. After-school studies generally had a positive impact on physical activity, fruit/vegetable consumption and caloric intake, or body composition. The single summer time intervention showed a trend towards reduced body mass index. Overall findings suggest that after-school and summer programmes, alone or perhaps in combination, offer potential benefits for African American youth and could favourably influence diet and physical activity behaviour.

Meal skipping linked to increased visceral adipose tissue and triglycerides in overweight minority youth

OBJECTIVE

To investigate the impact of eating frequency on dietary intake, physical activity (PA), metabolic, and adiposity measures in minority youth.

METHODS

This analysis included 185 overweight (≥85th BMI percentile) Hispanic and African-American youth (8-18 years) with the following cross-sectional measures: height, weight, BMI, dietary intake, body composition, metabolic parameters, PA, visceral adipose tissue (VAT), and subcutaneous adipose tissue. Each eating occasion (EO) was defined as ≥50 calories and ≥15 minutes from any previous EO. Participants were dichotomized based on EOs per 24-h into meal skippers <3 EO (MS; n = 27) or normal/frequent eaters ≥3 EO (NFE; n = 158). ANCOVAs were used to assess dietary intakes, metabolic outcomes, adiposity, and PA between eating frequency groups.

RESULTS

MS compared to NFE consumed 24% fewer calories per 24-h (P ≤ 0.01), 21% more calories per EO (P ≤ 0.01), ate 40% less often (P ≤ 0.01), had 18% higher triglycerides (P = 0.03), and 26% more VAT (P = 0.03), with no differences in PA.

CONCLUSIONS

Although meal skipping was associated with decreased energy intake, it was linked to increased calories per EO and higher triglycerides and VAT, which are strong indicators of deleterious metabolic profiles. These findings elucidate that meal skipping may be associated with increased VAT and related metabolic diseases in high-risk minority youth.

No association of dietary fiber intake with inflammation or arterial stiffness in youth with type 1 diabetes

AIM

To examine the association of dietary fiber intake with inflammation and arterial stiffness among youth with type 1 diabetes (T1D) in the US.

METHODS

Data are from youth ≥ 10 years old with clinically diagnosed T1D for ≥ 3 months and ≥ 1 positive diabetes autoantibody in the SEARCH for Diabetes in Youth Study. Fiber intake was assessed by food frequency questionnaire with measurement error (ME) accounted for by structural sub-models derived using additional 24-h dietary recall data in a calibration sample and the respective exposure-disease model covariates. Markers of inflammation, measured at baseline, included IL-6 (n=1405), CRP (n=1387), and fibrinogen (n=1340); markers of arterial stiffness, measured approximately 19 months post-baseline, were available in a subset of participants and included augmentation index (n=180), pulse wave velocity (n=184), and brachial distensibility (n=177).

RESULTS

Mean (SD) T1D duration was 47.9 (43.2) months; 12.5% of participants were obese. Mean (SD) ME-adjusted fiber intake was 15 (2.8) g/day. In multivariable analyses, fiber intake was not associated with inflammation or arterial stiffness.

CONCLUSION

Among youth with T1D, fiber intake does not meet recommendations and is not associated with measures of systemic inflammation or vascular stiffness. Further research is needed to evaluate whether fiber is associated with these outcomes in older individuals with T1D or among individuals with higher intakes than those observed in the present study.

The Role of Fructose, Sucrose and High-fructose Corn Syrup in Diabetes

Concerns are growing regarding the role of dietary sugars in the development of obesity and cardiometabolic diseases, including diabetes. High-fructose corn syrup (HFCS) and sucrose are the most important dietary sweeteners. Both HFCS and sucrose have overlapping metabolic actions with adverse effects attributed to their fructose moiety. Ecological studies have linked the rise in fructose availability with the increases in obesity and diabetes worldwide. This link has been largely underpinned by animal models and select human trials of fructose overfeeding at high levels of exposure. Although prospective cohort studies have shown significant associations comparing the highest with the lowest levels of intake sugar-sweetened beverages, these associations are small, do not hold at moderate levels of intake and are subject to collinearity effects from related dietary and lifestyle factors. Most systematic reviews and meta-analyses from controlled feeding trials have shown that fructose-containing sugars in isocaloric exchange for other carbohydrates do not show evidence of harm and, in the case of fructose, may even have advantages for glycaemic control, especially at small doses. Nevertheless, trials in which fructose-containing sugars supplement diets with excess energy have shown adverse effects, effects that appear more attributable to the excess energy than the sugar. There is no unequivocal evidence that fructose intake at moderate doses is directly related with adverse metabolic effects, although there is potentially cause for concern where fructose is provided at high doses or contributes excess energy to diets. Further investigation is warranted due to the significant knowledge gaps and weaknesses in existing research.

Metabolic basis of ethnic differences in diabetes risk in overweight and obese youth

The global pandemic of childhood obesity has led to increased risk for prediabetes and type 2 diabetes mellitus (T2DM). Studies have shown decreased insulin sensitivity and/or secretion with increasing adiposity and consistently observed greater risk for T2DM in obese, non-Caucasian youth. In the current review we describe recent advances in understanding how obesity and metabolic status in children and adolescents confers various risk profiles for T2DM among Latinos, African Americans, Caucasians, Asians, and Native Americans. These possible determinants include ectopic fat distribution, adipose tissue inflammation and fibrosis, and elevated plasma levels of nonesterified free fatty acids. Future work should aim to elucidate the ethnic-specific pathophysiology of T2DM in order to develop and implement appropriate prevention and treatment strategies based on different ethnic profiles of diabetes risk.

Exercise and insulin resistance in youth: a meta-analysis

BACKGROUND AND OBJECTIVES

The prevalence of obesity and diabetes is increasing among children, adolescents, and adults. Although estimates of the efficacy of exercise training on fasting insulin and insulin resistance have been provided, for adults similar estimates have not been provided for youth. This systematic review and meta-analysis provides a quantitative estimate of the effectiveness of exercise training on fasting insulin and insulin resistance in children and adolescents.

METHODS

Potential sources were limited to peer-reviewed articles published before June 25, 2013, and gathered from the PubMed, SPORTDiscus, Physical Education Index, and Web of Science online databases. Analysis was limited to randomized controlled trials by using combinations of the terms adolescent, child, pediatric, youth, exercise training, physical activity, diabetes, insulin, randomized trial, and randomized controlled trial. The authors assessed 546 sources, of which 4.4% (24 studies) were eligible for inclusion. Thirty-two effects were used to estimate the effect of exercise training on fasting insulin, with 15 effects measuring the effect on insulin resistance. Estimated effects were independently calculated by multiple authors, and conflicts were resolved before calculating the overall effect.

RESULTS

Based on the cumulative results from these studies, a small to moderate effect was found for exercise training on fasting insulin and improving insulin resistance in youth (Hedges' d effect size = 0.48 [95% confidence interval: 0.22-0.74], P < .001 and 0.31 [95% confidence interval: 0.06-0.56], P < .05, respectively).

CONCLUSIONS

These results support the use of exercise training in the prevention and treatment of type 2 diabetes.

Compensatory responses to insulin resistance in obese African-American and Latina girls

PURPOSE

Insulin responses to oral and intravenous glucose markedly differ by ethnicity. This study examined whether ethnic differences in pancreatic insulin secretion, hepatic insulin extraction and clearance explain these disparate findings in 35 obese African-American and 41 Latina girls (Tanner Stages: IV-V; ages: 14-18; body mass index percentile: 85.9-99.8%).

METHODS

Pancreatic insulin secretion, hepatic insulin extraction and clearance were estimated by C-peptide and insulin modeling during an oral glucose tolerance test. Insulin sensitivity (SI), acute insulin response to glucose (AIRG ) and disposition index were derived from a frequently sampled intravenous glucose tolerance test.

RESULTS

Compared to Latinas, obese African-American adolescents had lower pancreatic insulin secretion (21.3%; P < 0.01), glucose incremental area under the curve (IAUC) (41.7%, P = 0.02), C-peptide IAUC (25.1%, P < 0.01) and SI (33.7%; P < 0.01). There were no ethnic differences in hepatic insulin extraction and clearance (P's > 0.05).

CONCLUSIONS

Compensatory mechanisms to insulin resistance do not appear to explain the ethnic differences in insulin responses to oral and intravenous glucose in obese African-American and Latina girls.

High rates of fructose malabsorption are associated with reduced liver fat in obese African Americans

OBJECTIVE

African Americans commonly have lower liver fat accumulation than Hispanics, despite a similar propensity for obesity. Both ethnicities exhibit high consumption of fructose-containing beverages, which has been associated with high liver fat owing to the lipogenic properties of fructose. Therefore, differences in fructose absorption may be an important factor in regulating liver fat deposition. We hypothesized that fructose malabsorption in African Americans may reduce hepatic delivery of fructose, thus contributing to lower liver fat deposition compared to Hispanics.

METHODS

Thirty-seven obese young adults aged 21.4 ± 2.1 years (16 African American, 21 Hispanic) underwent a 3-hour hydrogen (H2) breath test to assess fructose malabsorption. Magnetic resonance imaging was used to determine visceral and subcutaneous adipose tissue volume and liver fat. Fructose malabsorption was expressed as an area under the curve for H2 production (H2 AUC).

RESULTS

Compared to Hispanics, African Americans had lower liver fat (5.4% ± 5.0% vs 8.9% ± 2.3%, p = 0.02) and a higher prevalence of fructose malabsorption (75.0% vs 42.9%; p = 0.05). Liver fat was negatively related to the extent of fructose malabsorption in African Americans (r = -0.53, p = 0.03), and this relationship was independent of the volumes of total fat and subcutaneous and visceral adipose tissue. There were no significant relationships between liver fat and fructose malabsorption in Hispanics.

CONCLUSION

African Americans have both a higher prevalence and a greater magnitude of fructose malabsorption than Hispanics. In African Americans, fructose malabsorption was negatively correlated with liver fat, which may be protective against fatty liver disease.

Liver fat has a stronger association with risk factors for type 2 diabetes in African-American compared with Hispanic adolescents

CONTEXT

Although overweight and obese African-Americans (AAs) have less visceral adipose tissue (VAT) and liver fat (LF) than Hispanics, they have a similar risk for type 2 diabetes.

OBJECTIVE

We examined ethnic differences in the association between VAT and LF with risk factors for type 2 diabetes to help explain this paradox.

DESIGN

We conducted a cross-sectional study in an academic pediatric care facility.

SUBJECTS

Subjects were overweight and obese AA (n = 131; 15.5 ± 3.3 years old) and Hispanic adolescents (n = 227; 14.7 ± 3.0 years old).

MAIN OUTCOME MEASURES

Outcome measures included insulin sensitivity (SI), acute insulin response (AIR), and disposition index (DI) by frequently sampled i.v. glucose tolerance test and minimal modeling.

RESULTS

LF, not VAT, was inversely associated with SI, and the effect of high LF compared with low was more pronounced in AAs (P(interaction) < .05). In Hispanics, high LF was associated with a 24% lower SI (P < .01) and a 31% increase in AIR (P < .01) and was not associated with DI (P = .35). In AAs, high LF was associated with a 49% lower SI (P < .001), was not associated with an increase in AIR (P = .25), and was associated with a 42% lower DI (P < .01), indicating failure of compensatory insulin secretion/clearance in response to insulin resistance. Prediabetes changed the relationship between high/low LF and DI in Hispanics (P(interaction) = .002) but not AAs such that prediabetic Hispanics with high LF had a 43% lower DI (P = .03) with no difference in those without prediabetes (P = .06).

CONCLUSIONS

LF has a stronger effect on SI compared with VAT. Our results suggest that the impact of high LF on poor β-cell compensation is more pronounced in AAs. In Hispanics, the combination of high LF and prediabetes contributes to poor β-cell compensation.

Effects of exercise alone on insulin sensitivity and glucose tolerance in obese youth

As with the dramatic increases in childhood obesity over the past decades, the incidence of type 2 diabetes has increased among children and adolescents in the United States. Insulin resistance is a common feature of childhood obesity and increases the risk of type 2 diabetes, metabolic syndrome, and atherogenic lipoprotein profile in obese youth. Although cross-sectional studies report beneficial effects of physical activity or cardiorespiratory fitness on insulin sensitivity, the role of regular exercise alone (e.g., no calorie restriction) as a strategy to reduce the risk of type 2 diabetes is unclear in obese children and adolescents. In this mini review, we examined the independent effects of various exercise on glucose tolerance and insulin sensitivity in obese youth.

Adverse metabolic effects of dietary fructose: results from the recent epidemiological, clinical, and mechanistic studies

PURPOSE OF REVIEW

The effects of dietary sugar on risk factors and the processes associated with metabolic disease remain a controversial topic, with recent reviews of the available evidence arriving at widely discrepant conclusions.

RECENT FINDINGS

There are many recently published epidemiological studies that provide evidence that sugar consumption is associated with metabolic disease. Three recent clinical studies, which investigated the effects of consuming relevant doses of sucrose or high-fructose corn syrup along with ad libitum diets, provide evidence that consumption of these sugars increase the risk factors for cardiovascular disease and metabolic syndrome. Mechanistic studies suggest that these effects result from the rapid hepatic metabolism of fructose catalyzed by fructokinase C, which generates substrate for de novo lipogenesis and leads to increased uric acid levels. Recent clinical studies investigating the effects of consuming less sugar, via educational interventions or by substitution of sugar-sweetened beverages for noncalorically sweetened beverages, provide evidence that such strategies have beneficial effects on risk factors for metabolic disease or on BMI in children.

SUMMARY

The accumulating epidemiological evidence, direct clinical evidence, and the evidence suggesting plausible mechanisms support a role for sugar in the epidemics of metabolic syndrome, cardiovascular disease, and type 2 diabetes.

Ectopic fat deposition in prediabetic overweight and obese minority adolescents

CONTEXT

Optimizing effective prevention and treatment of type 2 diabetes in youth is limited by incomplete understanding of its pathophysiology and how this varies across ethnicities with high risk.

OBJECTIVE

The aim of this study was to examine the contribution of visceral adipose tissue (VAT), hepatic fat fraction (HFF), and pancreatic fat fraction (PFF) to prediabetes in overweight/obese African American (AA) and Latino youth.

DESIGN AND SETTING

We conducted a cross-sectional study in an academic pediatric care facility.

SUBJECTS

A total of 148 healthy, overweight/obese adolescents (56 AA, 92 Latino; 72 males, 76 females; age, 15.5 ± 1.2 y; BMI z-score, 2.1 ± 0.5) participated in the study. They were normal glucose tolerant (n = 106) and prediabetic (n = 42), based on fasting glucose of 100-125 mg/dL and/or 2-hour glucose of 140-199 mg/dL, and/or hemoglobin A1C 6.0-6.4%.

MAIN OUTCOME MEASURES

We measured sc abdominal adipose tissue, VAT, HFF, and PFF by 3-Tesla magnetic resonance imaging and measured total body fat by dual-energy x-ray absorptiometry.

RESULTS

Adolescents with prediabetes had 30% higher HFF (P = .001) and 31% higher PFF (P = .042), compared to those with normal glucose tolerance after controlling for age, sex, pubertal stage, ethnicity, total percentage body fat, and VAT. Logistic regression showed that PFF predicted prediabetes in AAs and HFF predicted prediabetes in Latinos, with the odds of having prediabetes increased by 66% for every 1% increase in PFF in African Americans, and increased by 22% for every 1% increase in HFF in Latinos.

CONCLUSION

These data demonstrate that ectopic fat phenotypes associated with prediabetes are established by adolescence. Ethnic differences in the deposition of ectopic fat in adolescents with prediabetes may differ, with pancreatic fat in AAs, vs hepatic fat in Latino adolescents, being associated with diabetes risk.

Use of MRI and CT for fat imaging in children and youth: what have we learned about obesity, fat distribution and metabolic disease risk?

Childhood obesity is a matter of great concern for public health. Efforts have been made to understand its impact on health through advanced imaging techniques. An increasing number of studies focus on fat distribution and its associations with metabolic risk, in interaction with genetics, environment and ethnicity, in children. The present review is a qualitative synthesis of the existing literature on visceral and subcutaneous abdominal, intrahepatic and intramuscular fat. Our search revealed 80 original articles. Abdominal as well as ectopic fat depots are prevalent already in childhood and contribute to abnormal metabolic parameters, starting early in life. Visceral, hepatic and intramuscular fat seem to be interrelated but their patterns as well as their independent contribution on metabolic risk are not clear. Some ethnic-specific characteristics are also prevalent. These results encourage further research in childhood obesity by using imaging techniques such as magnetic resonance imaging and computed tomography. These imaging methods can provide a better understanding of fat distribution and its relationships with metabolic risk, compared to less detailed fat and obesity assessment. However, studies on bigger samples and with a prospective character are warranted.

Increasing Physical Activity Decreases Hepatic Fat and Metabolic Risk Factors

This study assessed the changes in time spent in moderate to vigorous physical activity (MVPA) on fat depots, insulin action, and inflammation. Longitudinal data were generated from 66 Hispanic adolescents (15.6±1.1 yr; BMI percentile 97.1±3.0) who participated in a 16-wk nutrition or nutrition+exercise intervention. There were no effects of the intervention on PA, but there were inter-individual changes in PA. For purposes of this analysis, all intervention groups were combined to assess how changes in PA during 16 wk affected changes in adiposity, insulin action, and markers of inflammation. MVPA was assessed by 7-day accelerometry, total body fat via DXA, liver fat by MRI, and insulin, glucose and HOMA-IR via a fasting blood draw. A repeated measures ANCOVA was used to assess the effect of MVPA on fat depots, insulin action, and inflammatory markers. Sixty-two percent of participants increased MVPA (mean increase, 19.7±16.5 min/day) and 38% decreased MVPA (mean decrease, 10.7±10.1 min/day). Those who increased MVPA by as little as 20 min per day over 16 wk, compared to those who decreased MVPA, had significant reductions in liver fat (-13% vs. +3%; P=0.01), leptin levels (-18% vs. +4%; P=0.02), and fasting insulin (-23% vs. +5%; P=0.05). These findings indicate that a modest increase in MVPA can improve metabolic health in sedentary overweight Hispanic adolescents.

Effects of a randomized maintenance intervention on adiposity and metabolic risk factors in overweight minority adolescents

OBJECTIVE

The objective of this study was to assess the effects of a maintenance programme (monthly newsletters vs. monthly group classes and telephone behavioural sessions) on obesity and metabolic disease risk at 1 year in overweight minority adolescents.

METHODS

After a 4-month nutrition and strength training intervention, 53 overweight Latino and African-American adolescents (15.4 ± 1.1 years) were randomized into one of two maintenance groups for 8 months: monthly newsletters (n = 23) or group classes (n = 30; monthly classes + individualized behavioural telephone sessions). The following outcomes were measured at months 4 (immediately following the intense intervention) and 12: height, weight, blood pressure, body composition via BodPod™ (Life Measurement Instruments, Concord, CA, USA), lipids and glucose/insulin indices via frequently sampled intravenous glucose tolerance test.

RESULTS

There were no significant group by time interactions for any of the health outcomes. There were significant time effects in several outcomes for both groups from months 4 to 12: bench press and leg press decreased by 5% and 14%, respectively (P = 0.004 & P = 0.01), fasting insulin and acute insulin response decreased by 26% and 16%, respectively (P < 0.001 & P = 0.046); while high-density lipoprotein cholesterol and insulin sensitivity improved by 5% and 14% (P = 0.042 & P = 0.039).

CONCLUSIONS

Newsletters as opposed to group classes may suffice as follow-up maintenance programmes to decrease type 2 diabetes and cardiovascular risk in overweight minority adolescents.