Sleep is Inversely Associated with Sedentary Time among Youth with Obesity

Sociodemographic disparities in sedentary time among US youth vary by period of the day

INTRODUCTION

Studies have reported sex and race/ethnicity disparities in sedentary time (ST), but none have evaluated ST by well-defined periods of the weekday (before school, during school, afterschool, and evening) and weekend day (morning, afternoon, and evening). Comparing sex and race/ethnicity disparities in ST at different periods of a weekday and weekend day can deepen our understanding of disparities and inform intervention efforts. This study tests sex and race/ethnicity disparities in ST by period of day in a representative sample of US youth.

METHODS

Youth (N = 2,972) from the 2003-2006 NHANES waves reported demographic variables and wore an accelerometer for 7 consecutive days to assess ST. Linear regressions were conducted to test relationships between sex and race/ethnicity and ST (min/hour) during each period of a weekday and weekend day. ST differences by sex and race/ethnicity were calculated to identify the periods of the day presenting the largest opportunity to reduce disparities.

RESULTS

Females were more sedentary than males during school (p < 0∙0001), afterschool (p < 0∙0001), and weekday evenings (p < 0∙0001) after controlling for covariates. After controlling for covariates, race/ethnicity only was a significant predictor of ST during weekend mornings (p < 0∙0001). During school and afterschool emerged as the periods with the largest opportunities to reduce sex disparities in ST. Weekend mornings were identified as the largest opportunity to reduce race/ethnic disparities in ST.

CONCLUSIONS

Sex disparities in ST appear to be driven mostly by the during school period of the day, while race/ethnic disparities in ST seem to be driven by the weekend morning period. Future intervention work should consider these periods when aiming to reduce ST disparities in youth.

Associations between sedentary behavior and health and the moderating role of physical activity in young people within a cross-sectional investigation

The purpose of this study was to determine the influence of sedentary behavior (SB) on the frequency of health complaints (fHC) as well as on self-rated health (SRH) and body mass index (BMI), and to determine whether physical activity (PA) moderated this influence. Data were obtained from the Youth Survey Luxembourg 2019 (N = 2,802), a nationally representative stratified random sample of all youths aged 16 to 29 years who were living in Luxembourg. fHC is a composite measure of eight common psychosomatic health complaints, SRH was measured on a five-point scale, and BMI was calculated by dividing participants' body weight by the square of their body height (kg/m2). PA and SB values were obtained from factor analyses of the relevant questionnaire items. SB was evaluated as both leisure-time SB and gaming-associated SB. Multiple regression analyses adjusted for age, sex, socioeconomic status, and migration status were used to determine the association between SB, fHC, BMI, and SRH. We found that leisure-time SB was positively associated with fHC, but not with SRH or BMI. Gaming-associated SB was positively associated with fHC and BMI but was negatively associated with SRH. PA was negatively associated with fHC, BMI and SRH. No statistically significant moderating effects were observed. We found that both leisure-time and gaming-associated SB showed statistically significant impacts on health. Although PA is known to be beneficial to health, we conclude that its potential to mitigate the negative effects of SB is limited in young people.

The association between lipid profile, oxidized LDL and the components of metabolic syndrome with serum mineral status and kidney function in individuals with obesity

BACKGROUND

Metabolic syndrome (MetS) is presented with a cluster of cardio-metabolic risk factors with widespread prevalence. In the present case-control study, we aimed to examine the relationship between several minerals and renal function tests with the components of MetS in individuals with obesity.

METHODS

This study included 127 individuals with obesity of both gender with or without MetS as the case and control, respectively. MetS was characterized based on the Adult Treatment Panel III (ATP III) criteria. Anthropometric variables and blood pressure were recorded. Mineral status including serum magnesium, copper, calcium, phosphorous, and iron were measured using standard colorimetric methods. Also, the serum lipid levels, concentrations of oxidized low-density lipoprotein (Ox-LDL), and renal function tests, including total protein, albumin, urea, creatinine, and uric acid were evaluated using commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

According to our results, individuals with obesity and MetS had higher levels of waist circumference (WC) and diastolic blood pressure (P < 0.05) compared to individuals with obesity and without MetS. Moreover, individuals with obesity and MetS had higher levels of serum total cholesterol (TC), triglyceride (TG), insulin, and iron (P < 0.05). In individuals with obesity and MetS, iron and albumin showed a positive relationship with LDL cholesterol and TG concentrations, respectively (P < 0.05 for all of them). Also, there was a positive association between serum magnesium and Ox- LDL in individuals with obesity with MetS. While, in individuals with obesity and without MetS, only a positive association between urea and uric acid with WC was observed (P < 0.05).

CONCLUSION

Our results suggest that disturbed serum lipids in obesity-metabolic syndrome is associated with homeostatic changes in the level of minerals or proteins that are involved in their metabolism. Although, further studies are needed to better explain and clarify the underlying mechanism of observed relationships.

Prolonged screen watching behavior is associated with high blood pressure among children and adolescents: a systematic review and dose-response meta-analysis

BACKGROUND

Numerous cardio-metabolic risk factors influence screen-related behaviors in children and adolescents. Numerous studies with inconsistent results revealed a relationship between blood pressure and screen time in the children and adolescents. This systematic review and meta-analysis summarized the data regarding the relationship between screen time and hypertension (HTN) in children and adolescents.

METHODS

We examined three electronic databases, including Scopus, PubMed, and Embase to find the recent research on the relationship between screen time and HTN up to 19 July 2022. Twenty papers were included in the final two-class and dose-response meta-analysis. We conducted subgrouping to identify the source of heterogeneity.

RESULTS

The highest category of screen time increased the odds of HTN by 8% [odds ratio (OR): 1.15; 95% confidence interval (CI): 1.08, 1.23; P < 0.001; I2 = 83.20%] and 1.9 mmHg increase in systolic blood pressure [weighted mean difference (WMD): 1.89; 95% CI: 0.18-3.62; P = 0.030; I2 = 83.4]. However, there was no significant difference in diastolic blood pressure. Moreover, screen time in hypertensive children and adolescents was 0.79 h (47.4 min) higher than normotensive subjects (WMD: 0.79; 95% CI: 0.02, 1.56; P = 0.046; I2 = 92.8). A departure from linearity was observed between increased screen time [digital video discs, personal computers, and video games and HTN (Pnonlinearity = 0.049).

CONCLUSION

This systematic meta-analysis review is the first to demonstrate a positive correlation between screen time and HTN in children and adolescents.

The interactive relationship of dietary choline and betaine with physical activity on circulating creatine kinase (CK), metabolic and glycemic markers, and anthropometric characteristics in physically active young individuals

BACKGROUND

There is conflicting evidence on the relationship between dietary choline and betaine with metabolic markers and anthropometric characteristics. The aim of this study is to investigate the relationship between the interaction effects of dietary choline and betaine and physical activity (PA) on circulating creatine kinase (CK), metabolic and glycemic markers, and anthropometric characteristics in active youth.

METHODS

In this cross-sectional study, data were collected from 120 to 18 to 35-year-old people. The food frequency questionnaire was used to assess dietary data; United States Department of Agriculture website was used to calculate choline and betaine in foods. CK, fasting blood sugar (FBS) and lipid profile markers were measured with ELISA kits. Low-density lipoprotein, and insulin sensitivity markers were calculated. Sociodemographic status, physical activity, and anthropometric characteristics were assessed based on a valid and reliable method. Analysis of co-variance (ANCOVA) tests adjusted for sex, PA, age, energy, and body mass index were used.

RESULTS

Increasing dietary betaine and total choline and betaine was positively related to weight, waist-to-hip ratio, fat-free mass and bone mass (P < 0.05). Increasing dietary betaine lowered total cholesterol (P = 0.032) and increased high density lipoprotein (HDL) (P = 0.049). The interaction effect of dietary choline and physical activity improved insulin resistance (P < 0.05). As well as dietary betaine interacted with physical activity increased HDL (P = 0.049). In addition, dietary total choline and betaine interacted with physical activity decreased FBS (P = 0.047).

CONCLUSIONS

In general, increasing dietary choline and betaine along with moderate and high physical activity improved insulin resistance, increased HDL, and lowered FBS in the higher tertiles of dietary choline and betaine.

The association between screen use and central obesity among children and adolescents: a systematic review and meta-analysis

Currently, there is no summative study evaluating the association between central obesity and screen time. This systematic review and meta-analysis aimed to summarize the results of studies evaluating the association between screen time and central obesity among children and adolescents. To this end, we performed a systematic search in three electronic databases, including Scopus, PubMed, and Embase to retrieve the related studies up to March 2021. Nine studies were eligible to be included in the meta-analysis. There was no association between odds of central obesity and screen time [odds ratio (OR) 1.136; 95% CI 0.965-1.337; P = 0.125]; however, waist circumference (WC) was 1.23 cm higher in those with highest screen time versus those in the lowest screen time category [weighted mean difference (WMD) = 1.23; 95% 95% CI 0.342-2.112; P = 0.007; Fig. 3]. Moreover, the possible sources of heterogeneity in the included studies were continent and sample size. No evidence of publication bias was reported. For the first time, the current systematic review and meta-analysis revealed that those with the highest screen time had higher WC compared with those with the lowest screen time. Although, there was no association between odds of central obesity and screen time. Due to the observational design of the included studies, it is impossible to infer the cause-effect relationship. Therefore, further interventional and longitudinal studies are warranted to better elucidate the causality of these associations.

The integrative panel of fatty acid desaturase-2 (FADS2) rs174583 gene polymorphism and dietary indices (DQI-I and HEI) affects cardiovascular risk factors among obese individuals

BACKGROUND

Recent studies have shown that dietary intakes and gene variants have a critical role in the obesity related comorbidities. This study aimed to evaluate the effects of the interactions between Fatty acid desaturase 2 (FADS2) gene rs174583 polymorphism and two dietary indices on cardiometabolic risk factors.

METHODS

This cross-sectional study was carried out on 347 obese adults aged 20-50 years old in Tabriz, Iran. Healthy eating index (HEI) and Diet quality index-international (DQI-I) were evaluated by a validated semi-quantitative 147-item Food frequency questionnaire (FFQ). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine FADS2 gene variants. Multivariate analysis of covariance (MANCOVA) was used to identify gene-diet interactions on metabolic parameters.

RESULTS

Waist circumference (WC) and serum triglyceride (TG) levels were significantly higher among carriers of TT genotype of FADS2 gene (P < 0.05). In addition, the interactions between FADS2 gene rs174583 polymorphism and DQI-I had significant effects on weight (P _interaction = 0.01), fat mass (P _interaction = 0.04), fat free mass (P _interaction = 0.03), and Body mass index (BMI) (P _interaction = 0.02); the highest level of these parameters belonged to TT carriers. Similarly, the interactions between FADS2 gene variants and HEI had significant effects on insulin (P _interaction < 0.001), Homeostasis model assessment of insulin resistance (HOMA-IR) (P _interaction < 0.001), Quantitative insulin check index (QUICKI) (P _interaction = 0.001), and alpha Melanocyte stimulating hormone (α-MSH) (P _interaction = 0.03).

CONCLUSION

In this study, for the first time, we reported the effects of gene-diet interactions on metabolic traits. Compliance with dietary indices (DQI-I and HEI) ameliorated the adverse effects of gene variants on metabolic risk factors, especially in heterogeneous genotypes. Further prospective cohort studies are needed to confirm these results.

Trend Impact Analysis (TIA) of community-based futures study for pediatric obesity in Iran

BACKGROUND

Childhood obesity has been regarded as one of the main healthcare challenges in the last century, leading to critical health problems and reduced life expectancy. Many factors can play a role in its development or prevention. Using the Trend Impact Analysis (TIA), this study aimed to conduct a community-based futures study for pediatric obesity in Iran.

METHODS

We obtained the prevalence of overweight and obesity from the database of the Ministry of Health and Medical Education. Moreover, we reviewed 21 documents, texts, and comments from three key stakeholders in Iran and prepared a list of key experts, who were stakeholders in the field of obesity prevention of childhood in different organizations. Then, we collected the expert opinions by Delphi method. Data analysis was performed using the Excel and R software.

RESULTS

Fourteen experts participated in the first stage and nine experts in the second stage. We identified two positive drivers, including the prevalence of coronavirus disease 2019 (COVID-19) and the widespread expansion of online educational programs. Meanwhile, we identified five negative drivers as follows: (1) controlling and limiting obesogenic environments in the community, school, and family; (2) running annual compulsory anthropometry programs for students of all educational levels in health centers; (3) integrating nutrition education interventions in the curricula of all educational levels; (4) taxation of unhealthy and fast foods; and (5) preparing safe and appropriate sports environments for children and adolescents (on the streets, schools, parks, and sports clubs). Without considering the drivers, the prevalence of overweight and obesity is predicted to reach 29.10% in 2031. However, it is expected that the negative drivers can increase the prevalence trend from 23.40% in 2018 to 19.57% in 2031, the positive drivers to 32.61%, and the combination of all drivers to 23.07%.

CONCLUSION

It seems that measures such as the effective communication of policy makers, basic evaluation of the programs and policies related to the prevention of childhood obesity, and localization of the programs of international organizations for the prevention of obesity can greatly control the prevalence of childhood obesity.

A high Diabetes Risk Reduction Score (DRRS) is associated with a better cardio-metabolic profile among obese individuals

BACKGROUND

Dietary indices and scores are valuable predictive markers against chronic diseases. Several previous studies have revealed the beneficial effects of diabetes risk reduction score (DRRS) against diabetes and cancer incidence. However, its association with metabolic abnormalities among obese individuals have not been revealed before. In the current study, we aimed to investigate the association between DRRS and metabolic risk factors among obese individuals.

METHODS

In the current cross-sectional study, 342 obese individuals [Body mass index (BMI) ≥ 30 kg/m²] aged 20-50 years were included. Dietary intake was assessed by a validated semi-quantitative food frequency questionnaire (FFQ) of 168 food items and DRRS was calculated. Metabolic syndrome (MetS) was defined based on the guidelines of the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III). Enzymatic methods were used to assess serum lipids, glucose, and insulin concentrations. Blood pressure was measured by a sphygmomanometer and body composition with bioelectrical impedance analysis (BIA).

RESULTS

Those with a higher adherence to DRRS had a significantly higher intake of energy, fiber, and lower protein compared with those in the lower quartiles. Moreover, lower intakes of trans fats, meat, sugar sweetened beverages (SSB), and glycemic index (GI) with higher intakes of fruits, cereal fiber, polyunsaturated fatty acids/ saturated fatty acids (PUFA/ SFA) ratio, coffee, and nuts were observed in the highest versus lowest DRRS categories. Lower systolic blood pressure, diastolic blood pressure, triglyceride and, higher high-density lipoprotein values were observed in higher DRRS categories. Logistic regression analysis showed that hypertension was significantly associated with adherence to DRRS among obese individuals, the odds ratio (OR) was 0.686 (95% confidence interval [CI], 0.26-0.84) after adjustment for potential confounders. But the risk of other components of MetS was not significantly associated with higher quartiles of adherence to DRRS. Also, a non-significantly lower prevalence of MetS was observed in the higher quartile of DRRS.

CONCLUSIONS

According to the results of the current study, higher DRRS was associated with lower blood pressure, modified serum lipids, and lower Mets prevalence. Further studies in different populations are warranted for better generalization of the obtained findings.

Childhood obesity risk increases with increased screen time: a systematic review and dose-response meta-analysis

BACKGROUND

The role of screen time in promoting obesity among children has been reported in previous studies. However, the effects of different screen types and the dose-response association between screen time and obesity among children is not summarized yet. In the current meta-analysis we systematically summarized the association between obesity and screen time of different screen types in a dose-response analysis.

METHODS

A systematic search from Scopus, PubMed and Embase electronic databases was performed. Studies that evaluated the association between screen time and obesity up to September 2021 were retrieved. We included 45 individual studies that were drawn from nine qualified studies into meta-analysis.

RESULTS

The results of the two-class meta-analysis showed that those at the highest category of screen time were 1.2 times more likely to develop obesity [odds ratio (OR) = 1.21; confidence interval (CI) = 1.113, 1.317; I2 = 60.4%; P < 0.001). The results of subgrouping identified that setting, obesity status and age group were possible heterogeneity sources. No evidence of non-linear association between increased screen time and obesity risk among children was observed (P-nonlinearity = 0.310).

CONCLUSION

In the current systematic review and meta-analysis we revealed a positive association between screen time and obesity among children without any evidence of non-linear association. Due to the cross-sectional design of included studies, we suggest further studies with longitudinal or interventional design to better elucidate the observed associations.

The association between healthy lifestyle score and risk of metabolic syndrome in Iranian adults: a cross-sectional study

BACKGROUND

Lifestyle risk factors, such as obesity, physical inactivity, smoking, and having an unhealthy diet are significantly associated to the risk of developing metabolic diseases such as type 2 diabetes, insulin resistance, and metabolic syndrome (MetS). Consequently, it is important to examine multiple lifestyle risk factors instead of single ones. Moreover, the combined effects of these factors on risk of MetS are not fully investigated. This study investigated the relationship between HLS and MetS and its components among apparently healthy adults living in Tabriz-Iran.

METHODS

This cross-sectional study includes 347 apparently healthy adults aged 20-50. To assess healthy lifestyle, four habits were used to examine HLS: physical activity (PA), smoking, healthy eating index-2015 (HEI-2015), and body mass index (BMI). Smoking status, PA, and dietary intakes (147-item) of study participants were evaluated using valid questionnaires. The lifestyle score ranged from zero (non-healthy) to four (most healthy) points. Binary logistic regression with adjusted models was used to examine the association of HLS and MetS, and its components. P < 0.05 was considered statistically significant.

RESULTS

In the current study, the average age and BMI of study participants were 40.78 ± 9.23 years old and 29.23 ± 5.97 kg/m², respectively. Participants in the highest quartile of HLS had significantly lower waist circumference (WC), BMI, weight, and had less fasting blood sugar (FBS), and triglyceride (TG) compared to the lowest quartile of HLS. Individuals in the second quartile of HLS had 24% greater odds for having MetS compared with those in the first quartile (adjusted OR: 1.24; 95% CI: 1.05-2.66). A significant reduction in hyperglycemia (adjusted OR: 0.85, 95% CI: 0.55-0.96) and high TG (adjusted OR: 0.83; 95% CI: 0.55-0.93) risk was also observed in the highest category of HLS compared to the lowest category. Moreover, after taking potential confounders into account, low score of HLS was associated with increased odds of MetS in women (adjusted OR: 1.32; 95% CI: 1.03-2.91).

CONCLUSION

The results showed that the lowest adherence to HLS was associated with higher odds MetS in women, after adjusting for all covariates. Moreover, adherence to a healthy lifestyle was related to lower odds of hyperglycemia and high TG in Iranian adults. To confirm these results, prospective studies are required.

Barriers and facilitators of childhood obesity prevention policies: A systematic review and meta-synthesis

Objectives

Childhood obesity is one of the worldwide considerable public health challenges and many factors can play a role in its management. Therefore, this article examined the facilitators and barriers of childhood obesity prevention (COP) policies.

Methods

This systematic review of qualitative studies was conducted via a search of the SCOPUS, PubMed, and Google Scholar databases between 1 January 2010 and 11 February 2022 and examined factors that influence the implementation of COP policies at a community approach.

Results

The parents' reluctance to engage in COP activities, lack of sufficient knowledge, and financial problems were the most reported barriers at the individual level. In addition, the beliefs about COP at the sociocultural level and limited funding and resources, time limitations in stakeholders at the implementation level, and lack of policy support at the structural level were the most frequently reported barriers. Further, effective communication between stakeholders and parents and school staff at the sociocultural level and flexibility of the intervention, delivery of healthy food programs in schools, low-cost and appropriate resources, and the availability of appropriate facilities are the most frequently reported facilitators in the structural level.

Conclusion

Individual, sociocultural, and structural level-related barriers and facilitators influence the implementation of COP policies. Most of the barriers and facilitators in this systematic review were related to the structural level.

Encouraging Tactics with Genetically Modified Probiotics to Improve Immunity for the Prevention of Immune-Related Diseases including Cardio-Metabolic Disorders

The PI3K/AKT/mTOR signaling pathway may play crucial roles in the pathogenesis of obesity and diabetes mellitus, as well as metabolic syndromes, which could also be risk factors for cardio-metabolic disorders. Consistently, it has been shown that beneficial effects may be convoyed by the modulation of the PI3K/AKT/mTOR pathway against the development of these diseases. Importantly, the PI3K/AKT/mTOR signaling pathway can be modulated by probiotics. Probiotics have a variety of beneficial properties, with the potential of treating specific diseases such as immune-related diseases, which are valuable to human health. In addition, an increasing body of work in the literature emphasized the contribution of genetically modified probiotics. There now seems to be a turning point in the research of probiotics. A better understanding of the interactions between microbiota, lifestyle, and host factors such as genetics and/or epigenetics might lead to a novel therapeutic approach with probiotics for these diseases. This study might provide a theoretical reference for the development of genetically modified probiotics in health products and/or in functional foods for the treatment of cardio-metabolic disorders.

Dietary glycemic index and glycemic load mediate the effect of CARTPT rs2239670 gene polymorphism on metabolic syndrome and metabolic risk factors among adults with obesity

INTRODUCTION

The importance of genetic and dietary factors in occurrence and progression of chronic diseases such as metabolic syndrome (MetS) has been established. However, complex interrelationships, including direct and indirect effects of these variables are yet to be clarified. So, our aim was to investigate the mediating role of glycemic indices in the relationship between CARTPT rs2239670 polymorphism, socio-demographic and psychological factors and metabolic risk factors and the presence of MetS in adults with obesity.

METHODS

In a cross-sectional study of 288 apparently healthy adults with obesity aged 20-50 years, dietary glycemic index (GI) and glycemic load (GL) were measured using a validated semi-quantitative food frequency questionnaire (FFQ). Biochemical parameters, blood pressure and anthropometric indicators were assayed by standard methods. Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Structural equation modeling (SEM) was used in the statistical analysis.

RESULTS

CARTPT rs2239670 had a positive direct effect on MetS (B = 0.037 ± 0.022; P = 0.043) and, on the other hand, this variant was found to be indirectly associated with MetS presence through mediation of GI (B = 0.039 ± 0.017; P = 0.009). CARTPT was a significant predictor of both dietary GI and GL (B = 1.647 ± 0.080 and B = 3.339 ± 0.242, respectively). Additionally, glycemic indicators appeared to mediate the association of age and gender with LDL-C (B = 0.917 ± 0.332; P = 0.006) and HDL (B = 1.047 ± 0.484; P = 0.031), respectively. GI showed a positive relationship with LDL-C (P = 0.024) in men and similar relationships were found between GL and LDL-C (P = 0.050) and cholesterol (P = 0.022) levels in women.

CONCLUSION

The SEM findings suggest a hypothesis of the mediating effect of glycemic indices in the relationship between genetic susceptibility to obesity and MetS presence. Our findings need to be confirmed with large prospective studies.

Developmental disparities in sedentary time by period of the day among US youth: a cross-sectional study

Background

Definitive evidence shows sedentary time (ST) is an independent risk factor for chronic disease, irrespective of physical activity. Despite calls to limit youth ST, studies demonstrate a spike in ST at the transition from childhood to adolescence. Identifying periods of the day (e.g., before school, during school, afterschool, and evenings) during which ST is higher in adolescents vs. children—that is, specifying when within daily routines ST disparities emerge—may be important to inform intervention strategies, as periods of the day correspond with variations in setting and supervision. The purpose of this study was to examine device-assessed ST engagement by period of day and developmental stage in a nationally representative sample of United States youth.

Methods

Youth (N = 2,972 between 6–18 years) from the 2003–2004 and 2005–2006 waves of NHANES reported demographic variables and wore an accelerometer for seven consecutive days to determine ST. Linear regression analyses were applied to study associations between ST and developmental stage (childhood or adolescence) by period of the week and weekend days, while controlling for sex, race/ethnicity, annual family income, and body mass index.

Results

Adjusted linear regressions (p-values < 0.0001) showed that adolescents were more sedentary than children during school, afterschool, and weekday evening periods as well as all the weekend periods. However, during school (36.3 ± 7.3 vs. 28.2 ± 7.2 min/hour; b = -7.4 [-8.1, -6.6]) and afterschool periods (31.1 ± 7.7 vs. 22.7 ± 7.0 min/hour; b = -7.8 [-8.6, -7.0]) showed the largest weekly ST disparities by developmental stage. Overall, the during school and after school hours constitute most (during school = 35% and afterschool = 16%) of the weekly ST disparity between children and adolescents.

Conclusions

Our data provide interventionists with estimates of the potential for ST reduction in each setting and period of the day among US adolescents. Future research should gather information about the barriers and facilitators of ST in adolescents by period of the day to help understand factors driving disparities.

The association between dietary glycemic index and cardio-metabolic risk factors in obese individuals

Background:

The dietary glycemic index (GI) has been introduced as a novel index to elucidate the potential of foods to increase postprandial glucose. According to the limited available data about the association of GI with cardio-metabolic risk factors such as lipid profile, blood glucose markers, and blood pressure in developing countries, the current study was conducted to investigate this association in apparently obese individuals.

Method and material:

Three hundred forty-seven obese adults were recruited in the present cross-sectional study. A validated 147-food item semi-quantitative food frequency questionnaire (FFQ) was used to evaluate the usual dietary intake of study participants. Dietary GI was calculated using the international GI database. Fatty acid desaturase (FADs)2 gene variants were determined according to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). ANOVA was used to compare study variables across different tertile of GI.

Results:

We found significant differences in terms of anthropometric parameters [weight (P = 0.038), waist circumference (WC) (P = 0.023), weight to hip ratio (WHR) (P = 0.007), and fat-free mass (FFM) (P < 0.001)] between different tertiles of GI. Similarly, energy and macronutrient intakes had a significant difference across dietary GI, and subjects with a higher dietary intake of energy and macronutrients (carbohydrate, protein, and total fat) were assigned to the third tertile of dietary GI (P < 0.001). While there was no significant difference in terms of cardio-metabolic risk factors in different dietary GI tertiles. Moreover, the total GI score was non-significantly higher in the TT genotype of FADS2 gene polymorphism compared with other genotypes. While no significant difference was observed between FADS2 genotype frequencies in different GI tertiles.

Conclusion:

Calculated dietary GI was associated with several cardio-metabolic risk factors in obese individuals. However, further prospective studies and clinical trials are needed to confirm our findings.

Leukocyte telomere length and obesity in children and adolescents: A systematic review and meta-analysis

Background: Several studies have revealed the negative effects of adiposity on telomere length shortening. However, the results of the studies assessing the negative relationship between obesity and leukocyte telomere length (LTL) are not consistent. This systematic review and meta-analysis are aimed to pool the results of articles assessing the relationship between obesity and LTL among children and adolescents. Methods: To retrieve the related studies, four online databases including PubMed, Embase, ProQuest, and Scopus were searched until May 2022. Observational studies evaluating the relationship between obesity and LTL among apparently healthy children and adolescents (aged ≤18 years) were included in the study. We considered the studies that had reported a mean ± standard deviation of LTL. The random-effects model was used to assess the pooled weighted mean difference (WMD) and a 95% confidence interval (CI). Results: The search yielded seven studies from an initial 3,403 records identified. According to the results of seven articles with 4,546 participants, obesity was associated with LTL shortening among children and adolescents (WMD = -0.081; 95% CI: -0.137 to -0.026; p = 0.004; I2 = 99.9%). Also, no publication bias was observed. According to the results of subgrouping, significant results were only attributed to the studies conducted in Europe, with high quality scores, among overweight and obese adolescents, with a baseline LTL lower than 1, and performed in community-based school settings. Also, according to the subgrouping and meta-regression results, the obesity definition criteria and baseline LTL were the possible sources of between-study heterogeneity. Conclusion: We observed shorter LTL among overweight and obese children and adolescents. To obtain more reliable results, further longitudinal prospective studies with large sample sizes and more consistent and accurate definitions of obesity are required.

Screen time increases overweight and obesity risk among adolescents: a systematic review and dose-response meta-analysis

Background

Adolescence is a critical period in human life, associated with reduced physical activity and increased sedentary behaviors. In this systematic review and dose-response meta-analysis, we evaluated the association between screen time and risk of overweight/obesity among adolescents.

Methods

A systematic search in electronic databases, including PubMed, Embase, and Scopus was performed up to September 2021. All published studies evaluating the association between screen time and risk of overweight/obesity among adolescents were retrieved. Finally, a total of 44 eligible studies were included in the meta-analysis.

Results

The results of the two-class meta-analysis showed that adolescents at the highest category of screen time were 1.27 times more likely to develop overweight/obesity (OR = 1.273; 95% CI = 1.166–1.390; P < 0.001; I-squared (variation in ES attributable to heterogeneity) = 82.1%). The results of subgrouping showed that continent and setting were the possible sources of heterogeneity. Moreover, no evidence of non-linear association between increased screen time and risk of overweight/obesity among adolescents was observed (P-nonlinearity = 0.311).

Conclusion

For the first time, the current systematic review and meta-analysis revealed a positive association between screen time and overweight/obesity among adolescents without any dose-response evidence.

Trial registration

The protocol of the current work has been registered in the PROSPERO system (Registration number: CRD42021233899).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-022-01761-4.

Screen Time and Body Mass Index Among Children and Adolescents: A Systematic Review and Meta-Analysis

Background

There is no summative quantitative study that report the difference in BMI in high screen user children and adolescents or give a difference in screen time in children and adolescents with obesity vs. children and adolescents without obesity. In the current meta-analysis we systematically summarized the association between obesity and screen time and meta-analyzed the results.

Methods

A systematic search from Scopus, PubMed and Embase electronic databases. Studies that evaluated the association between screen time and obesity up to June 2021.

Results

Results revealed that those at the highest screen time category had 0.7 kg/m2 higher BMI (WMD = 0.703; CI = 0.128, 1.278; P < 0.016; I 2 = 95.8%). Moreover, children and adolescents with obesity had a mean value of 0.313 h higher screen time compared with children and adolescents without obesity (WMD: 0.313; OR = 0.219, 0.407; P < 0.001; I 2 = 96%). The results of subgrouping showed that study quality, continent and sample size could reduce the heterogeneity values. No evidence of publication bias was reported according to visual asymmetry of funnel plots and the results of Begg's and Egger's tests.

Conclusion

For the first time, the current systematic review and meta-analysis revealed a positive association between screen time and obesity among children and adolescents. Due to the cross-sectional design of the included studies, causal inference is impossible, therefore, further studies in separate analysis of both genders are suggested to better elucidate gender-specific results.

Systematic Review Registration

[www.ClinicalTrials.gov], identifier [CRD4202123 3899].