In adult twins, visceral fat accumulation depends more on exceeding sex-specific adiposity thresholds than on genetics

Predicting Cardiometabolic Risk From Visceral Abdominal Adiposity in Persons With Chronic Spinal Cord Injury

Persons with spinal cord injury (SCI) have increased adiposity that may predispose to cardiovascular disease compared to those who are able-bodied (AB). The purpose of this study was to determine the relationships between dual energy X-ray absorptiometry (DXA)-derived visceral adipose tissue (VAT) and biomarkers of lipid metabolism and insulin resistance in persons with chronic SCI. A prospective observational study in participants with chronic SCI and age- and gender-matched AB controls. The study was conducted at a Department of Veterans Affairs Medical Center and Private Rehabilitation Hospital. The quantification of DXA-derived VAT volume (VAT_vol) and blood-derived markers of lipid and carbohydrate metabolism were determined in 100 SCI and 51 AB men. The VAT_vol was acquired from a total body DXA scan and analyzed using iDXA enCore CoreScan software (GE Lunar). Blood samples were collected for the serum lipid profile and plasma and glucose concentrations, with the latter two values used to calculate a measure of insulin resistance. In the SCI and AB groups, VAT% was significantly correlated with most cardiometabolic biomarkers. The results of the binary logistic regression analysis revealed that participants who had a VAT_vol above the cutoff value of 1630 cm³ were 3.1-, 4.8-, 5.6-, 19.2-, and 16.7-times more likely to have high serum triglycerides (R²_N= 0.09, p = 0.014), low serum high density lipoprotein cholesterol (R²_N = 0.16, p < 0.001), HOMA2-IR (R²_N = 0.18, p < 0.001), metabolic syndrome (R²_N = 0.25, p < 0.001), and a 10-yr Framingham Risk Score ≥ 10% (R²_N = 0.16, p = 0.001), respectively, when compared to participants below this VAT_vol cutoff value. Our findings reveal that persons with chronic SCI have a higher VAT_vol than that of AB controls, and VAT_vol correlates directly with biomarkers of lipid and carbohydrate metabolism that are strong predictors of cardiometabolic disorders.

Evaluating Relationships between Visceral Fat Measures and Adipokines Concentrations among Women with a History of Preeclampsia

OBJECTIVE

We sought to evaluate associations between postpartum plasma adipokine concentrations among women with a history of preeclampsia (PE) without severe features (MPE), PE with severe features (SPE), and no PE (NPE). We also investigated relationships between adipokines and computed tomography (CT)-quantified measures of visceral fat (VF) area (VFA) and subcutaneous fat area (SCFA).

STUDY DESIGN

We performed a secondary analysis of data collected as part of a previously performed cross-sectional study at our institution. Women with and without a history of PE were recruited in 10 years after delivery. VFA and SCFA measures were performed by CT scan. Anthropometric data and peripheral blood samples from subjects were collected concurrently.

RESULTS

Plasma adiponectin concentrations (µg/mL) were significantly lower among MPE (18.5 ± 7.1) compared with NPE (27.3 ± 13.8) and SPE (25.7 ± 9.6). Leptin (p = 0.32) and resistin (p = 0.93) concentrations were similar among the groups. Adiponectin concentrations more closely aligned with VFA (β = -0.001, p = 0.03), while resistin concentrations trended toward correlating with SCFA (β = 0.02, p = 0.05). Leptin was not preferential to VFA or SCFA.

CONCLUSION

VF distribution may contribute to the variation in PE phenotype. Adiponectin specifically may be a promising marker representing VFA.

Reaching the Tipping Point: Identification of Thresholds at which Visceral Adipose Tissue May Steeply Increase in Youth

OBJECTIVE

This study aimed to determine whether children and adolescents demonstrate, similarly to adults, a threshold of total percent body fat (%BF) above which the slope of visceral adipose tissue (VAT) rises.

METHODS

This cross-sectional study included 557 youth, aged 8 to 18 years, with a wide range of BMI values. Dual-energy x-ray absorptiometry was used to determine body composition (including VAT), and fasting blood was collected for measurement of lipids, glucose, insulin, and biomarkers. Segmented linear regression analysis identified the threshold for %BF unadjusted and adjusted for Tanner stage. Linear regression with robust variance estimation compared associations of risk factors and thresholds.

RESULTS

Thresholds of %BF were identified by sex (males = 33%, females = 38%), age (< 12 years = 34%; ≥ 12 years = 30%), and race (White/non-Hispanic = 31%; all other races/Hispanic = 38%) above which the slope of VAT was significantly steeper (all P < 0 .001). The percentage of total body fat stored as VAT was higher above versus below these thresholds (all P < 0.001). Above threshold, but not below it, VAT was associated with triglycerides/high-density lipoprotein ratio, insulin, adiponectin, and blood pressure.

CONCLUSIONS

The thresholds should be confirmed in longitudinal studies, and they may be useful in identifying youth at increased cardiometabolic risk in need of close clinical monitoring and/or intensive intervention to reduce excess adiposity.

Body Composition and Bone Mineral Density of Division 1 Collegiate Football Players: A Consortium of College Athlete Research Study

Bosch, TA, Carbuhn, AF, Stanforth, PR, Oliver, JM, Keller, KA, and Dengel, DR. Body composition and bone mineral density of Division 1 collegiate football players: a consortium of college athlete research study. J Strength Cond Res 33(5): 1339-1346, 2019-The purpose of this study was to generate normative data for total and regional body composition in Division 1 collegiate football players using dual-energy x-ray absorptiometry (DXA) and examine positional differences in total and regional measurements. Data were used from the Consortium of College Athlete Research (C-CAR) group. Four hundred sixty-seven players were included in this study. Height, body mass, total and regional fat mass, lean mass, and bone mineral density were measured in each athlete in the preseason (June-August). Players were categorized by their offensive or defensive position for comparisons. Linemen tended to have the higher fat and lean mass measures (p ≤ 0.05 for all) compared with other positions. Positions that mirror each other (e.g. linemen) had similar body composition and body ratios. All positions were classified as overweight or obese based on body mass index (BMI) (>25 kg·m), yet other than offensive and defensive linemen, all positions had healthy percent body fat (13-20%) and low visceral fat mass (<500 g). The data presented here provide normative positional data for total and regional fat mass, lean mass, and bone density in Division 1 collegiate football players. Player position had a significant effect on body composition measures and is likely associated with on-field positional requirements. From a player's health perspective, although all positions had relatively high BMI values, most positions had relatively low body fat and visceral fat, which is important for the health of players during and after their playing career. The increased accuracy and reliability of DXA provides greater information, regarding positional differences in college football players compared with other methods.

FTO genotype impacts food intake and corticolimbic activation

Background

Variants in the first intron of the fat mass and obesity-associated (FTO) gene increase obesity risk. People with "high-risk" FTO genotypes exhibit preference for high-fat foods, reduced satiety responsiveness, and greater food intake consistent with impaired satiety.

Objective

We sought central nervous system mechanisms that might underlie impaired satiety perception in people with a higher risk of obesity based on their FTO genotype.

Design

We performed a cross-sectional study in a sample that was enriched for obesity and included 20 higher-risk participants with the AA (risk) genotype at the rs9939609 locus of FTO and 94 lower-risk participants with either the AT or TT genotype. We compared subjective appetite, appetite-regulating hormones, caloric intake at a buffet meal, and brain response to visual food cues in an extended satiety network using functional MRI scans acquired before and after a standardized meal.

Results

Higher-risk participants reported less subjective fullness (χ2 = 7.48, P < 0.01), rated calorie-dense food as more appealing (χ2 = 3.92, P < 0.05), and consumed ∼350 more kilocalories than lower-risk participants (β = 348 kcal, P = 0.03), even after adjusting for fat or lean mass. Premeal, the higher-risk group had greater activation by "fattening" food images (compared with objects) in the medial orbital frontal cortex (β = 11.6; 95% CI: 1.5, 21.7; P < 0.05). Postmeal, the higher-risk subjects had greater activation by fattening (compared with nonfattening) food cues in the ventral tegmental area/substantia nigra (β = 12.8; 95% CI: 2.7, 23.0; P < 0.05), amygdala (β = 10.6; 95% CI: 0.7, 20.5; P < 0.05), and ventral striatum (β = 6.9; 95% CI: 0.2, 13.7; P < 0.05). Moreover, postmeal activation by fattening food cues within the preselected extended satiety network was positively associated with energy intake at the buffet meal (R2 = 0.29, P = 0.04) and this relation was particularly strong in the dorsal striatum (R2 = 0.28, P = 0.01), amygdala (R2 = 0.28, P = 0.03), and ventral tegmental area/substantia nigra (R2 = 0.27, P = 0.01).

Conclusion

The findings are consistent with a model in which allelic variants in FTO raise obesity risk through impaired central nervous system satiety processing, thereby increasing food intake. This study is registered at clinicaltrials.gov as NCT02483663.