Association Between Adipose Tissue Proton Density Fat Fraction, Resting Metabolic Rate and FTO Genotype in Humans.

Background: The difference of proton density fat fraction (PDFF) between supraclavicular and gluteal adipose tissue might indicate the presence of brown adipose tissue (BAT). Aim of this cross-sectional study was to investigate the association between PDFF over the supraclavicular fat region as a proxy of BAT proportion and resting metabolic rate (RMR). In addition, the association between the single nucleotide polymorphism (SNP) rs1421085 at the fat mass and obesity associated (FTO) gene locus and both PDFF and RMR was investigated. Methods: Anthropometric, clinical, and lifestyle data from 92 healthy adults (66.3% females, mean age: 36.2 ± 13.0 years, mean body mass index: 24.9 ± 5.4 kg/m2) were included in the analysis. The RMR was measured by indirect calorimetry. The magnetic resonance imaging (MRI) was used for the measurement of visceral and subcutaneous adipose tissue (VAT, SAT) volumes and for the measurement of adipose tissue PDFF. Results: Mean RMR of the whole group was 1 474.8 ± 242.2 kcal. Genotype data was available for 90 participants. After adjustment for age, sex, weight change and fat-free mass (FFM), no association was found between supraclavicular PDFF (p = 0.346) and gluteal PDFF (p = 0.252), respectively, and RMR, whereas statistically significant evidence for a negative association between delta PDFF (difference between gluteal PDFF and supraclavicular PDFF) and RMR (p = 0.027) was obtained. No statistically significant evidence was observed for per FTO risk allele change in RMR, gluteal and supraclavicular PDFF maps or volumes of VAT and SAT. Conclusions: Supraclavicular PDFF as a surrogate marker of BAT presence is not a determinant of RMR under basal conditions. In the present study, the FTO rs1421085 variant is not associated with either RMR or PDFF. Further studies are needed to elucidate the effect of BAT on RMR.

Association between Single Nucleotide Polymorphisms and Weight Reduction in Behavioural Interventions-A Pooled Analysis.

Knowledge of the association between single nucleotide polymorphisms (SNPs) and weight loss is limited. The aim was to analyse whether selected obesity-associated SNPs within the fat mass and obesity-associated (FTO), transmembrane protein 18 (TMEM18), melanocortin-4 receptor (MC4R), SEC16 homolog B (SEC16B), and brain-derived neurotrophic factor (BDNF) gene are associated with anthropometric changes during behavioural intervention for weight loss. genetic and anthropometric data from 576 individuals with overweight and obesity from four lifestyle interventions were obtained. A genetic predisposition score (GPS) was calculated. Our results show that study participants had a mean age of 48.2 ± 12.6 years and a mean baseline body mass index of 33.9 ± 6.4 kg/m2. Mean weight reduction after 12 months was -7.7 ± 10.9 kg. After 12 months of intervention, the MC4R SNPs rs571312 and rs17782313 were significantly associated with a greater decrease in body weight and BMI (p = 0.012, p = 0.011, respectively). The investigated SNPs within the other four genetic loci showed no statistically significant association with changes in anthropometric parameters. The GPS showed no statistically significant association with weight reduction. In conclusion there was no consistent evidence for statistically significant associations of SNPs with anthropometric changes during a behavioural intervention. It seems that other factors play a more significant in weight management than the investigated SNPs.

Knowledge, opinions and expectations of adults concerning personalised genotype-based dietary recommendations: a German survey.

OBJECTIVE: To assess the knowledge, opinions and expectations of persons with and without obesity concerning personalised genotype-based nutrition. DESIGN: Questions about nutrition, weight management and personalised genotype-based dietary recommendations were asked via standardised telephone-based interviews. Sociodemographic and anthropometric data were collected. The data were statistically weighted by age, gender, education, domicile and BMI. SETTING: Germany. PARTICIPANTS: Representative sample of the German population (n 1003) randomly sampled via a scientific Random Digit dial method plus 354 adults with a BMI ≥ 30·0 kg/m2 to enlarge the sample. RESULTS: Data of 1357 participants were analysed (51·1 % female, age: 50·5 ± 18·5 years, 15·9 % adults with a BMI ≥ 30·0 kg/m2). About 42 % or 19 % of the survey participants stated to know the terms personalised dietary recommendation or genotype-based dietary recommendation, respectively. Of those, 15·8 % indicated to have an experience with a personalised or genotype-based dietary recommendation. Almost 70 % of the survey participants believed that a genotype-based dietary recommendation is a reasonable measure for weight management. About 55 % of the survey participants pointed out that a genotype-based dietary recommendation is an effective concept in general. One-third of the survey participants (34·6 %) indicated to conceive the usage of a genotype-based dietary recommendation. CONCLUSION: Most of the survey participants did not know the term personalised or genotype-based dietary recommendation. One-third of the study participants are interested to use a genotype-based dietary recommendation. Therefore, more education of the public is necessary to properly help people making informed and serious decisions and assessing commercially available direct-to-consumer genetic tests.

Responsibility of Individuals and Stakeholders for Obesity and a Healthy Diet: Results From a German Survey.

INTRODUCTION: Overweight and obesity are thought to be mainly caused by an energy-rich diet and a sedentary lifestyle. The opinions of those with and without obesity about an individual´s and stakeholder´s responsibility for overweight and obesity as well as a healthy diet is rather unclear. Therefore, a survey was conducted to assess the thoughts of persons with and without obesity about the responsibilities for a high body weight and healthy diet. METHODS: This telephone-based survey was conducted in Germany. Landline and mobile phone users older than 17 years were quota sampled to represent the German population (n=1,003). Additionally, 354 adults with a body mass index (BMI) ≥ 30 kg/m2 were included in the survey population. Questions on weight management, eating and drinking and anthropometry were asked. Furthermore, the opinions of participants on the responsibility of individuals and stakeholders for obesity and a healthy diet were collected. Data was statistically weighted by age, gender, education, domicile, and BMI. RESULTS: Data of 1,357 persons (51.1% female, age: 50.5 ± 18.5 years, 15.9% with BMI ≥ 30 kg/m2) were analyzed. Participants responded that the general causes of a high body weight were low physical activity (82.7%) and excessive caloric intake (80.5%) followed by a lack of will power (72.1%). Almost 90% of the survey population reported that each individual is responsible for his/her own healthy diet. More than 85% of the survey population agreed that a healthy diet in kindergarten and nutrition education at schools should be the preferred approaches when politics take care of a person´s healthy diet. Sub-analyses revealed that BMI, sex, age, and education are potential confounders. CONCLUSION: This German survey showed that the majority of participants indicated that the responsibility for a healthy diet lies with the individual and high body weight is caused by self-controlled attitudes. These results suggest that the survey population underestimates societal and environmental factors that contribute to the development of obesity, which could lead to attitudes that facilitate weight-related stigmatization. Furthermore, survey participants indicated that they would support policy-driven measures that promote a healthy diet.

Investigation of the Relationship between MR-Based Supraclavicular Fat Fraction and Thyroid Hormones.

PURPOSE: Brown adipose tissue (BAT) plays a potential role in energy and glucose metabolism in humans. Thyroid hormones (TH) are main regulators of BAT development and function. However, it remains unknown how the magnetic resonance (MR)-based proton density fat fraction (PDFF) of supraclavicular adipose tissue used as a surrogate marker for BAT presence relates to TH. Therefore, the purpose of this analysis was to investigate the relationship between supraclavicular PDFF and serum levels of TH. METHODS: In total, 96 adult volunteers from a large cross-sectional study who underwent additional MR examination of the neck and pelvis were included in this analysis. Segmented PDFF maps of the supraclavicular and gluteal subcutaneous adipose tissue were generated. Delta PDFF was calculated as the difference between gluteal and supraclavicular PDFF and grouped as high (≥12%) or low (<12%) based on the median and the clinical rationale of a high versus low probability of BAT being present. Thyroid-stimulating hormone (mIU/L), free triiodothyronine (FT3, pg/mL) and free thyroxine (FT4, ng/dL) levels were determined in blood samples. Body mass index (BMI) was calculated as weight (kg)/height (m)2. Statistical analyses included the use of paired samples ttest, simple linear regression analysis and a multivariable linear regression analysis. RESULTS: The median age of the subjects (77% female) was 33 years, BMI ranged from 17.2 to 43.1 kg/m2. Supraclavicular and gluteal PDFF differed significantly (76.5 ± 4.8 vs. 89.4 ± 3.5 %, p < 0.01). Supraclavicular PDFF was associated with FT3 in subjects with high delta PDFF (R2 = 0.17, p < 0.01), with higher FT3 being associated with lower supraclavicular PDFF (y = 85.2 + -3.6 x). In a multivariable linear regression analysis considering further potential prognostic factors, the interaction between the delta PDFF group and FT3 remained a predictor for supraclavicular PDFF (B = -4.65, p < 0.01). DISCUSSION/CONCLUSIONS: Supraclavicular PDFF corresponds to the presence of BAT. In the present analysis, supraclavicular PDFF is correlated with FT3 in subjects with high delta PDFF. Therefore, the present findings suggest that biologically active T3 may be involved in the development of supraclavicular BAT.

Age- and BMI-related variations of fat distribution in sacral and lumbar bone marrow and their association with local muscle fat content.

This analysis investigated the age- and BMI-related variations of fat distribution in sacral and lumbar bone marrow and their association with local muscle fat content in order to detect fat distribution patterns and variations in healthy adults using proton density fat fraction (PDFF) measurements. A six-echo 3D spoiled gradient-echo sequence was used for chemical shift encoding-based water-fat separation at the sacral and lower lumbar region in 103 healthy volunteers. PDFF values of the sacrum, 5th lumbar vertebral body, the gluteal and paraspinal muscles were determined. Correlation with age was significant (p < 0.05) for PDFF of the sacrum (men (m): r = 0.58; women (w): r = 0.54), L5 (m: r = 0.58; w: r = 0.54), the gluteal (m: r = 0.51; w: r = 0.44) and paraspinal (m: r = 0.36; w: r = 0.49) muscles in both genders. BMI correlated significantly with the paraspinal musculature in men (r = 0.46) and women (r = 0.33). Correlation testing revealed significant correlations (p < 0.05) between the two osseous (m: r = 0.63, w: r = 0.75) and the muscle compartments (m: r = 0.63, w: r = 0.33) in both genders. Bone marrow and muscle fat infiltration patterns were not significantly associated with each other at the sacral and lower lumbar spine region. The presented data suggest that the two compartments may have distinct pathophysiological fat infiltration patterns. However, further clinical studies are needed to support the results.

Regional variation in paraspinal muscle composition using chemical shift encoding-based water-fat MRI.

BACKGROUND: Paraspinal musculature forms one of the largest muscle compartments of the human body, but evidence for regional variation of its composition and dependency on gender or body mass index (BMI) is scarce. METHODS: This study applied six-echo chemical shift encoding-based water-fat magnetic resonance imaging (MRI) at 3 Tesla in 76 subjects (24 males and 52 females, age: 40.0±13.7 years, BMI: 25.4±5.6 kg/m2) to evaluate the proton density fat fraction (PDFF) of psoas muscles and erector spinae muscles, with the latter being divided into three segments in relation to levels of spine anatomy (L3-L5, T12-L2, and T9-T11). RESULTS: For the psoas muscles and the erector spinae muscles (L3-L5), gender differences in PDFF values were observed (PDFF psoas muscles: males: 5.1%±3.4% vs. females: 6.0%±2.2%, P=0.006; PDFF erector spinae muscles L3-L5: males: 10.7%±7.6% vs. females: 18.2%±6.8%, P<0.001). Furthermore, the PDFF of the erector spinae muscles (L3-L5) showed higher PDFF values when compared to the other segments (PDFF erector spinae muscles L3-L5 vs. T12-L2: P<0.001; PDFF erector spinae muscles L3-L5 vs. T9-T11: P<0.001) and showed to be independent of BMI, which was not the case for the other segments (T12-L2 or T9-T11) or the psoas muscles. When considering age and BMI as control variables, correlations of PDFF between segments of the erector spinae muscles remained significant for both genders. CONCLUSIONS: This study explored regional variation of paraspinal muscle composition and dependency on gender and BMI, thus offering new insights into muscle physiology. The PDFF of the erector spinae muscles (L3-L5) was independent of BMI, suggesting that this level may be suited for representative paraspinal muscle segmentation and PDFF extraction as a biomarker for muscle alterations in the future.

Age- and gender-related variations of cervical muscle composition using chemical shift encoding-based water-fat MRI.

PURPOSE: To understand fat distribution patterns and ectopic fat deposition in healthy adults and to provide normative data, encompassing the borders of physiological regional muscle composition. For this purpose chemical shift encoding-based water-fat Magnetic Resonance Imaging (MRI) was used for proton density fat fraction (PDFF) calculations. MATERIAL AND METHODS: 91 volunteers were enrolled (male: n = 28, age = 36.6 ± 11.4 years; female: n = 63, age = 38.5 ± 15.1 years). PDFF values combined for the multifidus, semispinalis and spinalis cervicis muscles at the level of the 3rd cervical vertebral body (C3), the 5th cervical vertebral body (C5) and the first thoracic vertebral body (Th1) were extracted. RESULTS: The paraspinal musculature at C3 (14.8 ± 10.1 % vs. 19.2 ± 11.0 %; p = 0.029) and Th1 (13.8 ± 7.0 % vs 17.7 ± 7.4 %; p = 0.011) showed significantly lower PDFF values in men compared to women. Partial correlation testing with BMI as control variable revealed highly significant correlations between the paraspinal musculature PDFF at C3 (men: r = 0.504, p = 0.007; women: r = 0.279, p = 0.028), C5 (men: r = 0.450, p = 0.019; women: r = 0.347, p = 0.006) and Th1 (men: r = 0.652, p < 0.0001; women: r = 0.443, p < 0.0001) with age in both genders. CONCLUSION: The present data suggest gender and age-specific fat deposition patterns of the cervical and the upper cervicothoracic paraspinal muscles and may provide reference values for pathology detection.

A Scientific Perspective of Personalised Gene-Based Dietary Recommendations for Weight Management.

Various studies showed that a "one size fits all" dietary recommendation for weight management is questionable. For this reason, the focus increasingly falls on personalised nutrition. Although there is no precise and uniform definition of personalised nutrition, the inclusion of genetic variants for personalised dietary recommendations is more and more favoured, whereas scientific evidence for gene-based dietary recommendations is rather limited. The purpose of this article is to provide a science-based viewpoint on gene-based personalised nutrition and weight management. Most of the studies showed no clinical evidence for gene-based personalised nutrition. The Food4Me study, e.g., investigated four different groups of personalised dietary recommendations based on dietary guidelines, and physiological, clinical, or genetic parameters, and resulted in no difference in weight loss between the levels of personalisation. Furthermore, genetic direct-to-consumer (DTC) tests are widely spread by companies. Scientific organisations clearly point out that, to date, genetic DTC tests are without scientific evidence. To date, gene-based personalised nutrition is not yet applicable for the treatment of obesity. Nevertheless, personalised dietary recommendations on the genetic landscape of a person are an innovative and promising approach for the prevention and treatment of obesity. In the future, human intervention studies are necessary to prove the clinical evidence of gene-based dietary recommendations.

Differentiating supraclavicular from gluteal adipose tissue based on simultaneous PDFF and T2 * mapping using a 20-echo gradient-echo acquisition.

BACKGROUND: Adipose tissue (AT) can be classified into white and brown/beige subtypes. Chemical shift encoding-based water-fat MRI-techniques allowing simultaneous mapping of proton density fat fraction (PDFF) and T2 * result in a lower PDFF and a shorter T2 * in brown compared with white AT. However, AT T2 * values vary widely in the literature and are primarily based on 6-echo data. Increasing the number of echoes in a multiecho gradient-echo acquisition is expected to increase the precision of AT T2 * mapping. PURPOSE: 1) To mitigate issues of current T2 *-measurement techniques through experimental design, and 2) to investigate gluteal and supraclavicular AT T2 * and PDFF and their relationship using a 20-echo gradient-echo acquisition. STUDY TYPE: Prospective. SUBJECTS: Twenty-one healthy subjects. FIELD STRENGTH/SEQUENCE ASSESSMENT: First, a ground truth signal evolution was simulated from a single-T2 * water-fat model. Second, a time-interleaved 20-echo gradient-echo sequence with monopolar gradients of neck and abdomen/pelvis at 3 T was performed in vivo to determine supraclavicular and gluteal PDFF and T2 *. Complex-based water-fat separation was performed for the first 6 echoes and the full 20 echoes. AT depots were segmented. STATISTICAL TESTS: Mann-Whitney test, Wilcoxon signed-rank test and simple linear regression analysis. RESULTS: Both PDFF and T2 * differed significantly between supraclavicular and gluteal AT with 6 and 20 echoes (PDFF: P < 0.0001 each, T2 *: P = 0.03 / P < 0.0001 for 6/20 echoes). 6-echo T2 * demonstrated higher standard deviations and broader ranges than 20-echo T2 *. Regression analyses revealed a strong relationship between PDFF and T2 * values per AT compartment (R2 = 0.63 supraclavicular, R2 = 0.86 gluteal, P < 0.0001 each). DATA CONCLUSION: The present findings suggest that an increase in the number of sampled echoes beyond 6 does not affect AT PDFF quantification, whereas AT T2 * is considerably affected. Thus, a 20-echo gradient-echo acquisition enables a multiparametric analysis of both AT PDFF and T2 * and may therefore improve MR-based differentiation between white and brown fat. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:424-434.

Do lifestyle interventions during pregnancy have the potential to reduce long-term postpartum weight retention? A systematic review and meta-analysis.

Reducing postpartum weight retention is a promising strategy for addressing the rising prevalence of overweight and obesity in women. This systematic review and meta-analysis explored whether lifestyle interventions during pregnancy have the potential to reduce weight retention at 4 months postpartum and beyond. A search of five electronic databases for randomized controlled trials comparing the effect of weight-related lifestyle interventions beginning in pregnancy on postpartum weight retention to standard prenatal care groups was performed. Postpartum weight retention data was synthesized in a random-effects meta-analysis. Data from 14 studies of 7116 participants showed that the intervention group retained statistically significant less weight than the control group (weighted mean difference: -0.73 kg, 95% CI: -1.32 to -0.14, P = 0.015). Subgroup analysis showed this effect to be largest in studies with follow-ups from 4 to 6 months (weighted mean difference: -1.32 kg, 95% CI: -2.11 to -0.53, P = 0.001), but it remained significant until 12 months postpartum (weighted mean difference: -0.68 kg, 95% CI: -1.28 to -0.09, P = 0.023). In studies of women with a body mass index above 25.0 kg/m2 , no significant intervention effect was observed. More high-quality studies with a follow-up beyond 12 months postpartum are needed.

Gender- and Age-Related Changes in Trunk Muscle Composition Using Chemical Shift Encoding-Based Water⁻Fat MRI.

Ageing, sarcopenia, and malnutrition are associated with quantitative and qualitative changes of body composition. There are several imaging modalities, including magnetic resonance imaging (MRI), for the assessment of trunk muscle tissue composition. In this study, we investigated the gender- and age-related changes in trunk muscle composition using chemical shift encoding-based water⁻fat MRI. A total of 79 healthy volunteers (26 men: 38.9 ± 10.4 years; 53 women: 39.5 ± 15.0 years) underwent 3T axial MRI using a six-echo multi-echo 3D spoiled gradient echo sequence, allowing for the calculation of the proton density fat fraction (PDFF) in the trunk muscles. PDFF of the abdominal, psoas, and erector spinae muscles were determined. We detected significant positive correlations for abdominal muscle PDFF with age (r = 0.638, p = 0.0001) in men, and for abdominal muscle PDFF (r = 0.709, p = 0.0001) and erector spinae muscle PDFF (r = 0.674, p = 0.0001) with age in women. After adjustment for body mass index (BMI), only the correlation of age and abdominal muscle PDFF in women remained significant (r = 0.631, p = 0.0001). The findings of this study suggest that an increasing fat deposition in muscle is driven primarily by age, rather than BMI, in women. These results further support that PDFF can be considered a valid imaging biomarker of trunk muscle composition.

Associations Between C-Reactive Protein, Insulin Sensitivity, and Resting Metabolic Rate in Adults: A Mediator Analysis.

Objective: Long-term positive energy balance promotes the development of obesity, a main risk factor for type 2 diabetes mellitus (T2DM). While an association between increased resting metabolic rate (RMR) and insulin sensitivity (IS) was shown previously, the underlying mechanisms remain unclear. Aim of the mediator analysis was to investigate the role of inflammation within the association between RMR and IS. Methods: Anthropometric, clinical, and lifestyle data were collected according to standard operating procedures. RMR was measured using indirect calorimetry. Homeostasis model assessment for insulin resistance (HOMA-IR) was used as an IS parameter and C-reactive protein (CRP) was measured to represent the inflammatory status. Statistical analyses were performed using SPSS. Results: The analysis included 782 adults (517 females) with a mean age of 32.4 ± 12.0 years and a mean body mass index (BMI) of 24.6 ± 5.2 kg/m2. Regression analysis indicated a significant evidence for associations between RMR and HOMA-IR (ß = 39.3 ± 7.3 kcal/d; p ≤ 0.001) and CRP and HOMA-IR (ß = 0.5 ± 0.1; p ≤ 0.001) after adjustment for fat-free mass, sex, age, and study site. Results of the mediator analysis did not support the hypothesis that CRP is a mediator for the association between RMR and HOMA-IR. These results did not change after participant stratification according to sex or BMI. Conclusion: A significant evidence for an association between RMR and IS was shown in a large cohort. However, the inflammatory status, determined via CRP levels, was not a mediator within this association.

Associations between Single Nucleotide Polymorphisms and Total Energy, Carbohydrate, and Fat Intakes: A Systematic Review.

A better understanding of the genetic underpinning of total energy, carbohydrate, and fat intake is a prerequisite to develop personalized dietary recommendations. For this purpose, we systematically reviewed associations between single nucleotide polymorphisms (SNPs) and total energy, carbohydrate, and fat intakes. Four databases were searched for studies that assessed an association between SNPs and total energy, carbohydrate, and fat intakes. Screening of articles and data extraction was performed independently by 2 reviewers. Articles in English or German language, published between 1994 and September 2017, on human studies in adults and without specific populations were considered for the review. In total, 39 articles, including 86 independent loci, met the inclusion criteria. The fat mass and obesity-associated (FTO) gene as well as the melanocortin 4 receptor (MC4R) locus were most frequently studied. Limited significant evidence of an association between the FTO SNP rs9939609 and lower total energy intake and between the MC4R SNP rs17782313 and higher total energy intake was reported. Most of the other identified loci showed inconsistent results. In conclusion, there is no consistent evidence that the investigated SNPs are associated with and predictive for total energy, carbohydrate, and fat intakes.