Efficacy of different 8 h time-restricted eating schedules on visceral adipose tissue and cardiometabolic health: A study protocol.

BACKGROUND AND AIMS: To investigate the efficacy and feasibility of three different 8 h time-restricted eating (TRE) schedules (i.e., early, late, and self-selected) compared to each other and to a usual-care (UC) intervention on visceral adipose tissue (VAT) and cardiometabolic health in men and women. METHODS AND RESULTS: Anticipated 208 adults (50% women) aged 30-60 years, with overweight/obesity (25 ≤ BMI<40 kg/m2) and with mild metabolic impairments will be recruited for this parallel-group, multicenter randomized controlled trial. Participants will be randomly allocated (1:1:1:1) to one of four groups for 12 weeks: UC, early TRE, late TRE or self-selected TRE. The UC group will maintain their habitual eating window and receive, as well as the TRE groups, healthy lifestyle education for weight management. The early TRE group will start eating not later than 10:00, and the late TRE group not before 13:00. The self-selected TRE group will select an 8 h eating window before the intervention and maintain it over the intervention. The primary outcome is changes in VAT, whereas secondary outcomes include body composition and cardiometabolic risk factors. CONCLUSION: This study will determine whether the timing of the eating window during TRE impacts its efficacy on VAT, body composition and cardiometabolic risk factors and provide insights about its feasibility.

Differences in specific abdominal fat depots between metabolically healthy and unhealthy children with overweight/obesity: The role of cardiorespiratory fitness.

OBJECTIVES: Fat depots localization has a critical role in the metabolic health status of adults. Nevertheless, whether that is also the case in children remains under-studied. Therefore, the aims of this study were: (i) to examine the differences between metabolically healthy (MHO) and unhealthy (MUO) overweight/obesity phenotypes on specific abdominal fat depots, and (ii) to further explore whether cardiorespiratory fitness plays a major role in the differences between metabolic phenotypes among children with overweight/obesity. METHODS: A total of 114 children with overweight/obesity (10.6 ± 1.1 years, 62 girls) were included. Children were classified as MHO (n = 68) or MUO. visceral (VAT), abdominal subcutaneous (ASAT), intermuscular abdominal (IMAAT), psoas, hepatic, pancreatic, and lumbar bone marrow adipose tissues were measured by magnetic resonance imaging. Cardiorespiratory fitness was assessed using the 20 m shuttle run test. RESULTS: MHO children had lower VAT and ASAT contents and psoas fat fraction compared to MUO children (difference = 12.4%-25.8%, all p < 0.035). MUO-unfit had more VAT and ASAT content than those MUO-fit and MHO-fit (difference = 34.8%-45.3%, all p < 0.044). MUO-unfit shows also greater IMAAT fat fraction than those MUO-fit and MHO-fit peers (difference = 16.4%-13.9% respectively, all p ≤ 0.001). In addition, MHO-unfit presented higher IMAAT fat fraction than MHO-fit (difference = 13.4%, p < 0.001). MUO-unfit presented higher psoas fat fraction than MHO-fit (difference = 29.1%, p = 0.008). CONCLUSIONS: VAT together with ASAT and psoas fat fraction, were lower in MHO than in MUO children. Further, we also observed that being fit, regardless of metabolic phenotype, has a protective role over the specific abdominal fat depots among children with overweight/obesity.

Associations of fitness and physical activity with specific abdominal fat depots in children with overweight/obesity.

OBJECTIVES: To examine the relationship between physical fitness and physical activity (PA) with specific abdominal fat depots and their potential implications for cardiometabolic risk and insulin resistance (IR) in children with overweight/obesity. MATERIALS AND METHODS: A total of 116 children with overweight/obesity (10.7 ± 1.1 year, 54% girls) participated in the study. Abdominal visceral (VAT), subcutaneous (ASAT), and intermuscular abdominal adipose tissue (IMAAT) were assessed by magnetic resonance imaging. The cardiometabolic risk (MetS) score and the insulin resistance homeostasis model assessment (HOMA-IR) were calculated. Health-related physical fitness components (treadmill test, and 20 m shuttle run, handgrip, standing broad jump and 4 × 10 m tests) were evaluated, and PA was measured (accelerometry). Children were categorized as fit or unfit for each specific fitness test, and as active or inactive. RESULTS: Higher VAT, ASAT, and IMAAT were associated with higher MetS score and HOMA-IR (all p < 0.02). A better performance in all fitness tests and total and vigorous PA were strongly associated with lower VAT (all p < 0.04), ASAT (all p < 0.005), and IMAAT (all p < 0.005). Fit or active children had lower VAT, ASAT, and IMAAT (all p < 0.03) than their unfit or inactive counterparts. CONCLUSION: These results reinforce the importance of having adequate fitness and PA levels to reduce abdominal fat accumulation in children. Given that VAT, ASAT, and IMAAT are associated with higher risk of developing cardiovascular diseases and type 2 diabetes, the improvement of physical fitness by the promotion of PA should be goals of lifestyle interventions for improving health in children with overweight/obesity.

Differences in areal bone mineral density between metabolically healthy and unhealthy overweight/obese children: the role of physical activity and cardiorespiratory fitness.

OBJECTIVES: To examine whether areal bone mineral density (aBMD) differs between metabolically healthy (MHO) and unhealthy (MUO) overweight/obese children and to examine the role of moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF) in this association. METHODS: A cross-sectional study was developed in 188 overweight/obese children (10.4 ± 1.2 years) from the ActiveBrains and EFIGRO studies. Participants were classified as MHO or MUO based on Jolliffe and Janssen's metabolic syndrome cut-off points for triglycerides, glucose, high-density cholesterol and blood pressure. MVPA and CRF were assessed by accelerometry and the 20-m shuttle run test, respectively. Body composition was measured by dual-energy X-ray absorptiometry. RESULTS: In model 1 (adjusted for sex, years from peak high velocity, stature and lean mass), MHO children had significantly higher aBMD in total body less head (Cohen's d effect size, ES = 0.34), trunk (ES = 0.43) and pelvis (ES = 0.33) than MUO children. These differences were attenuated once MVPA was added to model 1 (model 2), and most of them disappeared once CRF was added to the model 1 (model 3). CONCLUSIONS: This novel research shows that MHO children have greater aBMD than their MUO peers. Furthermore, both MVPA and more importantly CRF seem to partially explain these findings.

Dietary determinants of hepatic fat content and insulin resistance in overweight/obese children: a cross-sectional analysis of the Prevention of Diabetes in Kids (PREDIKID) study.

Paediatric non-alcoholic fatty liver disease has increased in parallel with childhood obesity. Dietary habits, particularly products rich in sugars, may influence both hepatic fat and insulin resistance (homeostatic model assessment for insulin resistance (HOMA-IR)). The aim of the study was to examine the association of the consumption of foods and food components, dairy desserts and substitutes (DDS), sugar-sweetened beverages (SSB), as well as total and added sugars, with hepatic fat and HOMA-IR. Dietary intake (two non-consecutive 24 h-recalls), hepatic fat (MRI) and HOMA-IR were assessed in 110 overweight/obese children (10·6 (sd 1·1) years old). Linear regression analyses were used to examine the association of dietary intake with hepatic fat and HOMA-IR adjusted for potential confounders (sex, age, energy intake, maternal educational level, total and abdominal adiposity and sugar intake). The results showed that there was a negative association between cereal intake and hepatic fat (ß=-0·197, P<0·05). In contrast, both SSB consumption (ß=0·217; P=0·028) and sugar in SSB (ß=0·210, P=0·035), but not DDS or sugar in DDS or other dietary components, were positively associated with hepatic fat regardless of potential confounders including total sugar intake. In conclusion, cereal intake might decrease hepatic fat, whereas SSB consumption and its sugar content may increase the likelihood of having hepatic steatosis. Although these observations need to be confirmed using experimental evidence, these results suggest that healthy lifestyle intervention programs are needed to improve dietary habits as well as to increase the awareness of the detrimental effects of SSB consumption early in life.

Associations of dietary energy density with body composition and cardiometabolic risk in children with overweight and obesity: role of energy density calculations, under-reporting energy intake and physical activity.

This study examined (1) the association of dietary energy density from solid (EDS) and solid plus liquids (EDSL) with adiposity and cardiometabolic risk factors (CRF) in children with overweight and obesity, (2) the effect of under-reporting on the mentioned associations and (3) whether the association between ED and body composition and CRF is influenced by levels of physical activity. In a cross-sectional design, 208 overweight and obese children (8-12-year-old; 111 boys) completed two non-consecutive 24 h recalls. ED was calculated using two different approaches: EDS and EDSL. Under-reporters were determined with the Goldberg method. Body composition, anthropometry and fasting blood sample measurements were performed. Moderate to vigorous physical activity (MVPA) was registered with accelerometers (7-d-register). Linear regressions were performed to evaluate the association of ED with the previously mentioned variables. Neither EDS nor EDSL were associated with body composition or CRF. However, when under-reporters were excluded, EDS was positively associated with BMI (P=0·019), body fat percentage (P=0·005), abdominal fat (P=0·008) and fat mass index (P=0·018), while EDSL was positively associated with body fat percentage (P=0·008) and fat mass index (P=0·026). When stratifying the group according to physical activity recommendations, the aforementioned associations were only maintained for non-compliers. Cluster analysis showed that the low-ED and high-MVPA group presented the healthiest profile for all adiposity and CRF. These findings could partly explain inconsistencies in literature, as we found that different ED calculations entail distinct results. Physical activity levels and excluding under-reporters greatly influence the associations between ED and adiposity in children with overweight and obesity.

Effects of exercise on bone marrow adipose tissue in children with overweight/obesity: role of liver fat.

CONTEXT: Exercise reduces adiposity, but its influence on bone marrow fat fraction (BMFF) is unknown; nor is it known whether a reduction in liver fat content mediates this reduction. OBJECTIVES: (i) To determine whether incorporating exercise into a lifestyle program reduces the lumbar spine (LS)-BMFF, and (ii), to investigate whether changes in liver fat mediate any such effect. DESIGN: Ancillary analysis of a two-arm, parallel, non-randomized clinical trial. SETTING: Primary care centres in Vitoria-Gasteiz (Spain). PARTICIPANTS: A total of 116 children with overweight/obesity were assigned to a 22-week family-based lifestyle program (control group [n=57]) or the same program plus an exercise intervention (exercise group [n=59]. INTERVENTIONS: The compared interventions consisted of a family-based lifestyle program (two 90-minute sessions/month) and the same program plus supervised exercise (three 90-minute sessions/week). MAIN OUTCOMES AND MEASURES: The primary outcome examined was the change in LS-BMFF between baseline and 22 weeks, as estimated by MRI. The effect of changes in hepatic fat on LS-BMFF were also recorded. RESULTS: Mean weight loss difference between groups was 1.4±0.5 kg favour of the exercise group. Only the children in the exercise group experienced a reduction in LS-BMFF (effect size [Cohen d] -0.42, CI: -0.86, -0.01). Importantly, 40.9% of the reductions in LS-BMFF were mediated by changes in percentage hepatic fat (indirect effect: ß=-0.104, 95%CI=-0.213, -0.019). The impact of changes in hepatic fat on LS-BMFF was independent of weight loss. CONCLUSIONS AND RELEVANCE: The addition of exercise to a family-based lifestyle program designed to reduce cardiometabolic risk improves bone health by reducing LS-BMFF in children with overweight or obesity. This beneficial effect on bone marrow appears to be mediated by reductions in liver fat.

Impact of lifestyle moderate-to-vigorous physical activity timing on glycemic control in sedentary adults with overweight/obesity and metabolic impairments.

OBJECTIVE: Moderate-to-vigorous physical activity (MVPA) improves glucose levels; however, whether its timing affects daily glycemic control remains unclear. This study aims to investigate the impact of lifestyle MVPA timing on daily glycemic control in sedentary adults with overweight/obesity and metabolic impairments. METHODS: A total of 186 adults (50% women; age, 46.8 [SD 6.2] years) with overweight/obesity (BMI, 32.9 [SD 3.5] kg/m2) and at least one metabolic impairment participated in this cross-sectional study. MVPA and glucose patterns were simultaneously monitored over a 14-day period using a triaxial accelerometer worn on the nondominant wrist and a continuous glucose-monitoring device, respectively. Each day was classified as "inactive" if no MVPA was accumulated; as "morning," "afternoon," or "evening" if >50% of the MVPA minutes for that day were accumulated between 0600 and 1200, 1200 and 1800, or 1800 and 0000 hours, respectively; or as "mixed" if none of the defined time windows accounted for >50% of the MVPA for that day. RESULTS: Accumulating >50% of total MVPA during the evening was associated with lower 24-h (mean difference [95% CI], -1.26 mg/dL [95% CI: -2.2 to -0.4]), diurnal (-1.10 mg/dL [95% CI: -2.0 to -0.2]), and nocturnal mean glucose levels (-2.16 mg/dL [95% CI: -3.5 to -0.8]) compared with being inactive. This association was stronger in those participants with impaired glucose regulation. The pattern of these associations was similar in both men and women. CONCLUSIONS: These findings suggest that timing of lifestyle MVPA is significant. Specifically, accumulating more MVPA during the evening appears to have a beneficial effect on glucose homeostasis in sedentary adults with overweight/obesity and metabolic impairments.

Liver Fat, Bone Marrow Adipose Tissue, and Bone Mineral Density in Children With Overweight.

CONTEXT: Hepatic steatosis is associated with decreased bone mineral density (BMD). Bone marrow fat fraction (BMFF) could play a role in this relationship in children with obesity. OBJECTIVE: The objectives of this work were (i) to examine the relationship between the lumbar spine (LS) BMFF and BMD, and (ii) to explore the mediating role of LS-BMFF on the relationship between percentage hepatic fat with LS-BMD in preadolescent children with overweight/obesity. METHODS: Hepatic fat and LS-BMFF (magnetic resonance imaging) and areal LS-BMD (LS-aBMD, dual-energy x-ray absorptiometry) were measured in 106 children (aged 10.6 ± 1.1 years, 53.8% girls) with overweight/obesity. RESULTS: LS-BMFF was inversely associated with LS-aBMD (r = -0.313; P = .001) and directly related with percentage hepatic fat (r = 0.276; P = .005). LS-BMFF was significantly greater in children with than without hepatic steatosis (P = .003; Cohen's d: 0.61; 95% CI, -0.21 to 1.0), while no significant difference was seen between children with overweight and those with obesity (P = .604; Cohen's d: 0.16; 95% CI, -0.21-0.55). Mediating analysis indicated that LS-BMFF is an important mediator (50%) in the association of hepatic fat with lower LS-aBMD (indirect effect: ß = -.076; 95% CI, -0.143 to -0.015). CONCLUSION: These findings suggest that hepatic steatosis, rather than overall excess adiposity, is associated with greater bone marrow adipose tissue in preadolescent children with overweight/obesity, which in turn, is related to lower BMD. Hepatic steatosis could be a potential biomarker of osteoporosis risk, and a therapeutic target for interventions that aim to reduce not only hepatic steatosis, but for those designed to improve bone health in such children.

Independent and Joined Association between Socioeconomic Indicators and Pediatric Obesity in Spain: The PASOS Study.

Childhood obesity is a public health problem worldwide. An important determinant of child and adolescent obesity is socioeconomic status (SES). However, the magnitude of the impact of different SES indicators on pediatric obesity on the Spanish population scale is unclear. The aim of this study was to assess the association between three SES indicators and obesity in a nationwide, representative sample of Spanish children and adolescents. A total of 2791 boys and girls aged 8 to 16 years old were included. Their weight, height, and waist circumference were measured. SES was assessed using two parent/legal guardian self-reported indicators (educational level -University/non-University- and labor market status -Employed/Unemployed-). As a third SES indicator, the annual mean income per person was obtained from the census section where the participating schools were located (≥12.731€/<12.731€). The prevalence of obesity, severe obesity, and abdominal obesity was 11.5%, 1.4%, and 22.3%, respectively. Logistic regression models showed an inverse association of both education and labor market status with obesity, severe obesity, and abdominal obesity (all p < 0.001). Income was also inversely associated with obesity (p < 0.01) and abdominal obesity (p < 0.001). Finally, the highest composite SES category (University/Employed/≥12.731€ n = 517) showed a robust and inverse association with obesity (OR = 0.28; 95% CI: 0.16-0.48), severe obesity (OR = 0.20; 95% CI: 0.05-0.81), and abdominal obesity (OR = 0.36; 95% CI: 0.23-0.54) in comparison with the lowest composite SES category (Less than University/Unemployed/<12.731€; n = 164). No significant interaction between composite SES categories and age and gender was found. SES is strongly associated with pediatric obesity in Spain.